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Virgin Galactic successfully reaches space (bbc.com)
592 points by adzicg 4 months ago | hide | past | web | favorite | 215 comments



For context, the predecessor of SpaceShipTwo reached an altitude of over 100km in June 2004, becoming the first commercial venture to put a person in space [1]. A few months after that, Virgin got involved and it seemed like commercial passenger spaceflight was just a few years away. 14 years and two fatal accidents [2,3] later, the 80 km flight seems to pale in comparison to those expectations. In that time we’ve seen the rise of SpaceX and Blue Origin, whose aspirations and capabilities look set to far exceed those of Virgin Galactic. As impressive as this spaceplane is, its competitors are starting to make it look like the product of some (very expensive) backyard tinkering.

[1] https://en.wikipedia.org/wiki/SpaceShipOne#Development_and_w...

[2] https://en.wikipedia.org/wiki/RocketMotorTwo#Related_test_pr...

[3] https://en.wikipedia.org/wiki/VSS_Enterprise_crash


Right now Blue Origin and Virgin Galactic are in about the same place, with SpaceShipTwo ahead of New Shepard in terms of test flights (and presumably crew rating). Both will provide suborbital tourist flights.

SpaceX isn't in that game; they're trying to get the Falcon 9 crew-rated for orbital flights. If Blue Origin's New Glenn ever gets off the ground, they may pursue an orbital crew rating as well.


Blue Origin is presently spending a great deal of money developing New Glenn. I would be very surprised if we don't see a flight test of the "v1.0" full scale rocket before 2025.

Virgin Galactic has nothing in development with anywhere near the velocity capability for low earth orbit. Going up in a parabola to 100 km or 150 km and then coming back down again, a few hundred km down range, is a very different sort of delta-v requirement versus putting something in a stable orbit.

They are in "about the same place" for things that are flying now, but for the next generation beyond that, Blue Origin is far ahead.


>If Blue Origin's New Glenn ever gets off the ground

Are you having doubts?


Few doubts given their benefactor's unlimited resources, but it's worth remembering how unexpected SpaceX's successes were.

I'm mainly pointing that it's odd to compare aspirations with accomplishment. I've thought about climbing Everest, and even planned a route and bought some gear, but that doesn't put me in the same category as Norgay or Hillary.


They were originally aiming for 100km, and at early space tourism conferences (about a decade ago) would point out that other competitors (e.g. Lynx, at the time) weren't actually going to 100km so couldn't claim they were going to space (they would do this reliably, and to the growing annoyance of the audience who didn't want audience-question time hijacked for Virgin PR, e.g. in a Q&A panel that had a Lynx team member onboard, a virgin person would always ask a question like 'Just to confirm, you're not flying above 100km, the altitude at which space starts?').

However, the performance of Spaceship 2's engines has fallen short of the original design goal, making it incapable of reaching 100km, so they are now using a different definition of Space for PR purposes.


The Ars Technica article on this event [0] contains this interesting snippet:

>Probably the closest thing to [an internationally agreed upon boundary for "space"] comes from the World Air Sports Federation, or FAI, which uses 100km (the Karman line) to delineate the boundary of space for the purposes of establishing world records. However, this organization says it is looking at lowering this boundary from 100km to 80km, due to "Recently published analyses (that) present a compelling scientific case for reduction in this altitude."

>Much of the push for a lowering of the boundary has come because of work by Harvard University astrophysicist Jonathan McDowell, who has argued that orbiting objects can survive multiple perigees at altitudes around 80 to 90km and that this altitude range is consistent with the highest physical boundary of the atmosphere, the mesopause.

Does anyone here know more about this? How recent is this work? How controversial is it, if it is at all? This is the first I've heard of work along these lines.

[0]: https://arstechnica.com/science/2018/12/virgin-galactic-just...


I haven't heard of this, but it does sound logical.

The Mesosphere is defined as ending at an altitude of 85km. The next and last layer of the atmosphere is the Thermosphere, which end at 690km, but this is higher than the altitude at which most Shuttle missions orbited, for example.

(The "Exosphere" is above the Mesosphere, extending out to 10,000km, but gas particles in this layer are so far apart they do not behave as a "gas".)

So the most reasonable "boundary" of space would seem to be 85km.

As an aside: The lowest altitude at which an object in a circular orbit can complete at least one full revolution without propulsion is approximately 150km.

The "sky" does not turn completely black until 160km.


85km =~ 270,000 feet for those used to thinking in airline terms.


or 85000 meters or 52.8 miles


The defined boundary of space always reminds me of Jeannette Piccard, the first woman in space (as defined in 1934).

https://en.wikipedia.org/wiki/Jeannette_Piccard

It's interesting where we define what is an isn't space, with its own cultural ramifications.


It’s hard to argue that you’ve left the atmosphere, when the craft you’re using is supported by it. Hence the Karman Line.

Tereshkova has a much better claim to being the first woman in space.


You can reach the surface of a lake in a craft that floats on water so you should be able to reach the end of the atmosphere in a craft that floats on it.


The surface of a lake is much more well-defined, though, and has high density. You can't "float" on whatever you define as the "surface" of the atmosphere.


Jeanette Piccard and her husband Jean, another high-altitude ballooning pioneer, are also suggested to be ancestors of one Jean-Luc Picard, captain of the USS Enterprise.


I've always explained the boundary as the point at which, in order to use wings to provide enough lift to keep you in the sky, you have to be travelling at orbital speeds.

As the air gets thinner you have to travel faster in order to displace enough air to keep you aloft, and there comes a point where you're in orbit anyway, so the lift isn't needed.

Different planes have different lifting surfaces, so I have always wondered if the line was set more or less arbitrarily using some 'standard' plane, or if all planes approach the same limit together.

Looks like there are some interesting things to read here!


> The edge of space: Revisiting the Karman Line

> Jonathan C. McDowell

> In this paper I revisit proposed definitions of the boundary between the Earth's atmosphere and outer space, considering orbital and suborbital trajectories used by space vehicles. In particular, I investigate the inner edge of outer space from historical, physical and technological viewpoints and propose 80 kilometers as a more appropriate boundary than the currently popular 100 km Von Kármán line.

https://arxiv.org/abs/1807.07894


Yep, the Karman line is 100km. Only astronauts and X-15 pilots who flew above this heigh were deemed to have flown into space.

Virgin and Branson are very good at marketing and PR, so they probably chose the lower definition to say they had reached space.


The US gave astronaut wings to anyone who flew above 50 miles (about 80 km), not 100 km:

https://en.wikipedia.org/wiki/United_States_Astronaut_Badge#...


For anyone looking wistfully at the $250k price tag of a VG sub-orbital flight I suggest checking out Zero-G:

https://www.gozerog.com

They fly short (~30sec) sub-orbital parabolas in a regular commercial jet (with a custom interior). It's not quite like going into "space" but it is quite literally only 2% of the cost for (IMHO) >80% of the value. The total amount of zero-G time is about the same as it will be on the VG sub-orbital flight (~5 mins). I've done it and it's an awesome experience.


> A ZERO-G Experience® is available starting at $4,950 per person.

Even less! 1.94% of the cost. :)

Part of the experience that I'm looking for is the perspective of seeing so much of the planet at the same time Ride in a U2: https://www.youtube.com/watch?v=w-COlil4tos

You can get a ride up pretty high (and fast in a Mig too) https://migflug.com/flights-prices/mig-29-edge-of-space/


Per memory, you can also do it at NASA Space Camp as an additional, optional activity. (Or, at least, appropriately aged children can)

I'm not sure how much it was: I did it back in the 90s.

It was a prop plane, but I remember probably ~5-10 seconds of perceived weightlessness. Which seems longer than you might expect when your stomach and contents are suddenly floating freely in your chest cavity. ;)

I'd definitely recommend it. It was... unique


Are there commercial U2 rides?


When the Mythbusters took a ride in a U2 there were several days of training including how to operate the pressure suit required for the trip. I don't know of any commercial U2 rides and I assume it would cost way more than the Zero G plane ride.


The U2 has to be flown so extremely precisely that I think it would be too expensive and dangerous to offer commercial rides.


My startup, Shuttle.io, is earth's first spaceflight booking marketplace, and are partners with Zero-G. We're hosting a party this Saturday in San Francisco all about Zero-G, preparing for our upcoming charter flights:

eventbrite.com/e/zero-g-launch-party-tickets-53416542316

If you're interested in learning more about Zero-G, I'd love to see you there. We're hosting a Zero-G charter flight out of the Bay Area in March. If you're interested, please reach out to me at avery@shuttle.io!


Huh. I thought this was stupid, then realized I was... maybe?

Space tourism is pretty niche. A booking marketplace doesn't really make sense right now, so I assume your real goal is to create the market by incentivizing supply through crowd funding/aggregating demand for various "levels" of space tourism? What economies of scale are you targeting? Do you have a timeline for collecting deposits?

If I'm wrong, please consider the above anyway :) Personally, I won't settle for less than a few LEO laps.


I think your link didn't copy right :(



Why do you think 80% of the value is in the Zero-G time? You could similarly argue that 80% of the Zero-G experience can be had by indoors skydiving at 2% of that flight's cost.


Indoor skydiving isn't zero-g -- you experience 1g from air resistance. Indoor skydiving gives you a similar sensation as floating in water.

The closest cheap thing is probably the few seconds you get on a trampoline.


People who jump out of planes will also experience 1G due to air resistance when they reach terminal velocity. That's why it's called indoor skydiving instead of indoor spacewalking.


"You know that feeling, when you're in the air while jumping on a trampoline? I feel like that all the time."


OK, I'll bite. Inner ear disorder?



Hey, thanks :)

I'd never heard of him, and it was too much of a paraphrase for the search services that I tried.

Maybe we need a search service that understands language, and can do "that sounds like ...".


Or a high jump into deep water.


Well yeah, I didn't say that it was exactly like it. It does give you the ability to float and even do tricks in the (moving) air and experience Newton's laws almost like in Zero-G, though.


I've done both and you'll just have to take my word for it or try it yourself, but the two activities are not even remotely comparable.


I think that indoor skydiving is closer to the Zero-G flight than the Zero-G flight is to the Virgin Galactic's space trip on a rocket launching from a plane, getting to Mach 2.9, getting an out-of-this-world view, and gliding to the landing. Do you disagree?

Your comment about the 80% of the value came out as dismissive of Virgin Galactic's achievement. This is a company that is trying to come back after a deadly crash that could've stopped further work and to initiate space tourism. I get the usual HN contrarian skepticism, as I've participated in it also, but to see this comparison as one of the top comments here is disappointing.


That may well be. Having not gone into space I can't speak authoritatively on that. However, I can say this: seeing the view from space is a visual experience. Visual experiences can be simulated, e.g. with VR, or high-def video. A simulated visual experience is very similar to the real thing.

Free fall is different. Yes, you can get brief periods of free fall on, say, a roller coaster, or by jumping off a high dive. I have done all of these things, so I can tell you authoritatively that being in free fall for 30 seconds, not strapped in, and with no wind rushing past you, is completely different than being in free fall for a third of a second (high dive) or even three seconds (roller coaster). YMMV, of course, but for me that feeling of floating is a big draw of going into space. I'm sure the view is very nice too, but I've seen it.


I'd say that 80% of the value lies in getting to see Earth against the black backdrop of space. As the pilot in today's flight said, "million dollar view".


Colloquially known as 'the vomit comet'


How are you able to achieve 0G while still within the escape velocity of earth, what's the science behind this?


> what's the science behind this?

Earth's gravity in low-earth orbit is almost the same as on the surface [1]. What makes things on the ISS float isn't their distance from earth. It's horizontal (or more accurately, tangential) speed. Objects in orbit are in free fall.

To replicate that, parabolic flights free fall. (Parabolic paths are similar to the elliptical paths orbiting objects take [2].) They then stop free falling (to avoid hitting the ground) before climbing back up and doing it again and again. And again.

[1] https://en.wikipedia.org/wiki/Low_Earth_orbit#Orbital_charac...

[2] https://history.nasa.gov/conghand/traject.htm


This always reminds of the Hitchhikers Guide: "There is an art, it says, or rather, a knack to flying. The knack lies in learning how to throw yourself at the ground and miss."

ISS constantly falls down to earth. It is also moving so fast that it constantly misses earth.


>> ISS constantly falls down to earth. It is also moving so fast that it constantly misses earth.

I'm gonna have to roll up some herb while you explain this comment further.


Think of firing a canon sideways: it takes a while for the cannon ball to drop and hit the earth. Now imagine firing it faster and faster, till eventually it's dropping at the same rate as the earth curves. That is essentially what the ISS is doing at a height of about 400km above the surface.


It’s worth noting that if you shoot a cannonball dead horizontally, it hits the ground at the same time as it would if dropped from the same height [1].

It just has more horizontal speed, so it travels sideways a decent amount during its fall.

Anyways, yes, the ISS is scooting sideways so fast that, in the time it would have taken to fall straight down, the ground beneath it has dropped away by an amount equal to its initial height, so the thing stays at the same altitude.

[1]: *This hurt my brain when I first heard it, but I promise it’s true: it’s just that cannons are normally fired at an upward angle, giving them upward velocity and thus “hang time.”


> It’s worth noting that if you shoot a cannonball dead horizontally, it hits the ground at the same time as it would if dropped from the same height

I think this is assuming the ground is flat, which isn't a good assumption when talking about orbits.


It’s a perfectly fine assumption when talking about cannons, which are typically earthbound and have low projectile speeds.

I discuss orbits in the next paragraph, where I hope it’s evident I don’t assume a flat plane :)


> It’s worth noting that if you shoot a cannonball dead horizontally, it hits the ground at the same time as it would if dropped from the same height

Do you have a citation for this? I'd expect, as with all physics questions, there's a caveat.

In this case, "... over sufficiently small distances."

If you fire, say, the main guns of a battleship "over the horizon" (from your initial vantage point), I'd strongly suspect this doesn't hold.

In order for it to, the gravitational force vector, integrated over flight path, would have to perfectly counter the curvature of the Earth... which doesn't seem like it would line up so neatly.

In reality, air friction and maximum muzzle velocities probably render most of these concerns moot for practical purposes.


"Do you have a citation for this?"

This is Newtonian physics.

Obviously, air, other things, friction mess it up.

But essentially that's it.

Horizontal motion of a body won't affect gravitations vertical pull.


Aka orthogonal vectors won't affect each other.

Does this hold true as an object's ballistic trajectory approaches significant fractions of a planet's diameter?

Granted, the object is constantly being accelerated towards the center of the planet.

But that force vector's direction changes with respect to the initial "horizontal" launch vector as the object continues on a straight path, until they're longer orthogonal.


The force of gravity is always orthogonal to the direction of motion when in orbit. So never loses momentum. Which is why the moon is still going around the earth a billion years later and has not 'fallen' into it.


This is only true for circular orbits. It’s pretty transparently obvious that elliptical orbits move closer to and farther from the center of mass (and lose and gain momentum accordingly).


We're talking suborbital velocities here.

If I'm wrong, I'd love to hear exactly why, but regurgitating basic physics doesn't resolve the difficulties in modelling a straight flight path around a curved surface, in relation to a dropped object.


in a completely Newtonian universe (ignoring relativity), if you shoot the ball at high enough speed it will never hit the earth. horizontal motion doesn't affect the vertical pull, but the direction of the vertical pull changes by the time the ball's traveled well over the horizon.


> in a completely Newtonian universe (ignoring relativity), if you shoot the ball at high enough speed it will never hit the earth.

Right. Assuming a perfectly spherical earth, at below orbital velocity, it hits the ground somewhere; at orbital velocity up to (but excluding) escape velocity it (assuming the cannon gets out of the way) orbits with the low point at (and opposite) the firing position, and beyond escape velocity it takes a curving path getting ever farther away.


It doesn't take into account the curvature of the earth. The commenter was assuming a simpler flat plane.


> If you fire, say, the main guns of a battleship "over the horizon"

...then you are not firing horizontally, but upwards. If you would insist on orienting those guns perpendicular to the gravity vector you would get a very big splash not too far away.

I'm not an artillerist, but as far as I know (and supported by a quick glance at Wikipedia), the range advantage of those big guns over smaller ones doesn't come from higher muzzle velocity (which is limited by the physical property of the propellant independent of gun size), but from the much higher kg/CdA value of their very big projectiles.


> there's a caveat

Air.


> It’s worth noting that if you shoot a cannonball dead horizontally, it hits the ground at the same time as it would if dropped from the same height

No, it doesn't, because the Earth is curved, and air resistance. With a relatively dense, aerodynamic shell and energy sufficient for only a short flight time, both of these effects are minimal, so it's approximately true, but lose any of those and it stops being a good approximation.


And the important part about orbits is that wind resistance won't slow it down significantly. At a low orbit like the ISS it touches the atmosphere ever so slightly and needs a boost every now and then.


What they mean is by "moving so fast" is, it's moving so fast horizontally. Imagine being at the top of a steep mountain and throwing a rock directly out from you. The rock will continue to move horizontally, due to the force behind your throw, as well as vertically, as it drops due to gravity. If you don't throw it hard enough, then the trajectory of the rock won't clear the mountain slope. If you throw it too hard, it will clear the base of the mountain by a wide margin. But if you throw it just right, the rock could hypothetically have a trajectory that is perfectly parallel to the mountain slope (in reality, due to things like air resistance, this isn't all that feasible).

Anything in orbit it literally the exact same. You get something moving fast enough horizontally that even though the Earth's gravity is still pulling on it, its trajectory towards earth is perfectly parallel (actually often not perfectly, but in principle) with the curvature of the planet. But by doing it high enough in the sky, you can escape the atmosphere of the earth, to where there is no wind resistance, meaning once you get up to a high horizontal speed, you can turn off the engines and coast perpetually without slowing down.

So everything in orbit, from the ISS to satellites, to the moon, are all in Earth's gravity well and are falling towards the planet, but they have a horizontal speed as well that keeps them from colliding with the surface. The Earth and the rest of the planets in the solar system do the same thing in terms of their orbit with the Sun.

It's also why sometimes satellites or space junk that have been in the sky for years will come crashing down to Earth. Sometimes the calculations for how fast you need to be going are off, or something will throw off it's horizontal momentum, and that will cause it's trajectory to dip just enough that it is no longer orbiting the earth perfectly, but instead is spiraling ever so slightly towards the surface, and will over the course of months or years or decades dip closer and closer until it enters the atmosphere, at which time air resistance becomes a factor again and it breaks up and really plummets.


> But if you throw it just right, the rock could hypothetically have a trajectory that is perfectly parallel to the mountain slope (in reality, due to things like air resistance, this isn't all that feasible).

Not quite. Ignoring air resistance, any throw you could possibly produce will have a parabolic trajectory, which means it could be parallel with the mountain slope only if the slope itself is parabolic.


This is correct, and I was making a simplification. A better example would be a curved hill.


Nitpicking here, but the trajectory would be approximately elliptical, not parabolic. A parabolic trajectory would require a uniform gravitational field.


> A parabolic trajectory would require a uniform gravitational field.

A uniform gravitational field is such a good approximation for the situation described that I didn't think of including that proviso. Ballistic trajectory calculations close to the Earth's surface assume constant g.


To clarify for anyone reading, the difference is not constant vs variable magnitude of g, it's constant vs variable direction of g. Gravity is a vector pointing at the (weighted by inverse of distance squared) centre of mass, so once you are operating on a global scale you have to account for the direction of g changing as you move around.

The force always pointing towards a single point is what causes an ellipse to form. If the force always pointed down it would be a parabola, and over short distances on the surface this is a really good approximation.


Only now when re-reading your comment do I realize that you said "any throw you could possibly produce", in which case you are correct. I was thinking that you were talking more about the "fire a stupendously powerful cannon to get an orbital (or closeish) trajectory" situation, in which case the velocities would be high enough to not use a uniform gravitational field. My apologies for the misunderstanding.


How do they maintain horizontal velocity?


The ISS? It's above the atmosphere so there is no air resistance to slow it down. The velocity is constant after the initial boost into orbit.

Actually that's not quite correct, I believe it is not quite out of the atmosphere completely and as such there is a (very) small amount of air resistance and they have to fire engines to boost back into the appropriate orbit every once in a while.


It is always accelerating straight toward the center of the planet at ~1G.


https://xkcd.com/2011/ - so ignoring the sarcasm in the comic, the two red lines are "throwing a ball" like you are used to - and the black line is the ball that never quite reaches the ground - i.e. the ISS.


You've already collected a nice set of replies, but here's another way of looking at it: Imagine the Earth is a single point mass at its center of mass. Now consider the collection of orbits around it. You still have (to a first approximation) all current orbital possibilities as you know and love them. But now you also have a lot of new orbits. There's orbits just a few inches above the point mass that require nearly the speed of light. There's orbits at what is now ground level. And there are all kinds of elliptical orbits that go through what is now the ground.

All of those orbits represents trajectories in which you are in free fall.

The primary reason these orbits don't "exist" is that they impact the surface of the Earth [1]. However, if you "ride" one of these orbits briefly, you still get the free fall effect, just as if you were in orbit! It's just that you can't stay on the orbit freely because of the minor issue of surface impact.

When you juggle or something, the balls are actually, very briefly, in orbit. Minus air resistance, which is a big deal for a ball. (I initially wrote "throw a baseball", but air resistance becomes a factor very quickly even then.) With a powered projectile, like, say, an airplane, you can deliberately overcome the air resistance for a while and stay in the orbit for longer, even through the atmosphere.

It may seem like a bizarre idea of "powering" through an orbit, but it's perfectly reasonable. It's still a gravitational orbit, it's just that electromagnetic forces (contact forces) are getting involved and mucking up the purity of the orbit, so we cancel them out briefly with other ones via the jet engines. If you had a device that could continue powering through the Earth, you could stay at free-fall even through the rock.

[1]: The secondary reason is that the Earth isn't the aforementioned point mass. A neutrino could hypothetically "orbit" through the Earth for a while before being captured, but its orbit will be complicated by the fact that as it goes below the surface, the "mass" of the Earth starts dropping. Which makes me wonder if there ever are any such neutrinos. The only thing stopping such a thing from existing is the need for a process to create neutrinos that have less than escape velocity for the Earth, and I'm not sure if there is such a process.


Free fall. Like inside an elevator with a broken cable. Here the aeroplane starts the free fall with considerable upwards speed. That and the horisontal speed form an upward parabola path of free fall.


That's how Hollywood studios do a lot of their anti-gravity shots as well. They have to be shot really quickly, in short takes, with custom planes that have movie sets built into the interior. It's pretty crazy and dangerous when you think about it.


Fascinating. Didn't know they use real zero-g. Do you have links to any articles that describe the process in more detail?


Here's a video of Kevin Bacon and Bill Paxton in the vomit comet from Apollo 13: https://www.youtube.com/watch?v=5IAAjk3QdU8


There are a whole lot of random sharp edges there to be jumping around and then suddenly dropping out of the air every 30 seconds. one of them almost faceplants into something, yikes!


They fly the plane downward, matching the vertical acceleration with the acceleration caused by gravity.

You owe it to yourself to see these amazing videos filmed on planes that simulate zero G:

OK Go - https://www.youtube.com/watch?v=LWGJA9i18Co

Physics Girl - https://www.youtube.com/watch?v=q1_AJWZajEk

Veritasium - https://www.youtube.com/watch?v=SAQ-iIJkLzA


> They fly the plane downward, matching the vertical acceleration with the acceleration caused by gravity

"Contrary to popular misconception, the 0 g freefall phase of flight begins as the aircraft climbs, and does not occur solely as the aircraft descends. Although the aircraft has upward velocity during the initial 0 g phase, its acceleration is downward: the upward velocity is decreasing" [1].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2598414/


Good clarification, thanks. By "downward", I meant downward acceleration, not necessarily downward velocity, although colloquial usage of "downward" usually means velocity.


And Stephen Hawking! https://youtu.be/jhCPincElC4?t=49


Same way you’d experience it in an elevator if someone cuts the safety cable. With a plane they can repeatedly climb / drop to recreate the experience.


Emergency brake on the elevator will mess with your carefully laid plans. In freefall it will only drop for so much before the clamps engage.


I didn’t say the cable broke, I said somebody cut it. In that situation they’ve likely tampered with the safety clamps as well.


There's a difference between experienced "G-Force" and the amount you are accelerating due to gravity.

Basically, gravity can accelerate you all that it wants, but if there is no force resisting that acceleration (air drag, your feet against the ground, the seat pushing on your back in an airplane) then you don't feel that acceleration.

https://en.wikipedia.org/wiki/G-force

"Gravitation acting alone does not produce a g-force, even though g-forces are expressed in multiples of the acceleration of a standard gravity. Thus, the standard gravitational acceleration at the Earth's surface produces g-force only indirectly, as a result of resistance to it by mechanical forces. These mechanical forces actually produce the g-force acceleration on a mass. For example, the 1 g force on an object sitting on the Earth's surface is caused by mechanical force exerted in the upward direction by the ground, keeping the object from going into free fall."


Astronaut training is done the same way in a modified Boeing 727(? IIRC), nicknamed the "vomit comet". As a student pilot I used to love doing heavy-G steep climbs then pushing the nose over and enjoying a few seconds of weightlessness....


Another way of picturing this, is what happens when you throw a baseball. You typically aim at about a 45 degree angle, let it lose from you hand, then from that point on the ball experiences free fall until it lands on something (well, not exactly, due to air resistance, but close enough).


An airplane can get closer. It can actively compensate for air resistance.


Any time you fall freely you experience this. If you jump off a table you are weightless[1]. Unfortunately a planet is accelerating at you so the experience doesn’t last long.

You can choose your frame of reference when considering interacting masses. I choose mine, which gives the interpretation above.

[1] ignoring buoyancy and drag from air, which are small in this scenario.


Because 0G is a (slightly imprecise) term for weightlessness, and weightlessness is by definition when the only force acting on a body is the gravitational force.

If you're in an elevator, and the elevator cable snaps, you'll be in free fall (at least initially), although you are nowhere near the escape velocity.


Any time you're not resting on a surface, hanging from something, or otherwise being held up against gravity, you're in freefall.

("Zero G" is admittedly a bad term, since there's no such thing as "zero G" literally anywhere in the universe. It's all freefall.)


You can't truly experience freefall except in a vacuum or in an object that is producing an accelerating force to counteract the force of air resistance (like a really fast elevator, or a vomit comet plane).

The reason is that the air itself is imparting substantial acceleration upon you from you hitting it, which leads to terminal velocity. Once you reach terminal velocity the air pressure is imparting exactly the same kind of force against you to repel gravity as the floor would be at ground level, so you experience one full g. You only really feel weightless the moment you jump off a surface, before you've accumulated any velocity and thus before you're being accelerated by air resistance.


> Once you reach terminal velocity the air pressure is imparting exactly the same kind of force against you to repel gravity as the floor would be at ground level, so you experience one full g.

And what's interesting, is that what feels "down" is actually "up". Which is one of the gotchas in flying.

> You only really feel weightless the moment you jump off a surface, before you've accumulated any velocity and thus before you're being accelerated by air resistance.

This is a very useful thing in ice skating, skiing, martial arts, etc. Especially combined with changing moment of inertia.


Have done Zero G, it's fun if you have money to burn. The floating is fun but I got sick towards the end.


Net G relative to your frame of motion is zero G is a better way to put it.

G is a unit. 9.81 Newtons. So 3G is 3*9.81 newtons.


It’s “g”. “G” is the gravitanional constant.


9.81 Newtons per kilogram.


The jet flies parabolic arcs in the sky. If you imagine you shoot a bullet on a 45 degree angle upwards, it follows a ballistic path in a big arc right? Now fly that same path with a big plane. The bullet and the plane are both in freefall essentially.


> what's the science behind this?

The same: in both cases the vessel is falling toward earth accelerating at 1g, so for the passenger that are also experiencing 1g of gravity it feels like they're floating


Try jumping.


Pretty common misconception, but what you're implying is not how/why you have 0G in space. So for instance the space station still experiences about 90% of Earth's gravity. Orbit is about going really fast, horizontally. If you flew straight up to the ISS, you'd fall right back down. This is why when you see a rocket take off their course looks extremely bent - it's not an optical illusion.

So why horizontally? Imagine there was no air resistance on Earth. If you shot a bullet that bullet would keep going until the force of gravity pulled it down and it hit the Earth. But now imagine that you shoot it fast enough that the vertical distance gravity is pulling it down is less than the vertical distance it gains due to the curvature of the Earth. That equilibrium is exactly what orbit is. It also leads to the highly counter intuitive fact that the height of a given circular orbit is determined exclusively by how fast an object is moving relative to the body it's orbiting. Mass doesn't matter.

Okay so back to the plane. If it's not intuitive yet imagine throwing a ball. It works exactly the same as our bullet, but we can visualize one important part easier. The ball's trajectory will be a parabola. And at the highest point of that parabola the net vertical force on the ball is zero. It's where the force you exerted on it to send it up, and the force of gravity pulling it down eventually reach an equilibrium. Something inside of that ball would experience 0g at the moment when it was at its parabolic peak. And that's exactly what these planes do. They simply 'throw' the planes into a parabolic path, and the passengers experience near 0 g while traveling through the parabolic peak.


> at the highest point of that parabola the net vertical force on the ball is zero

This is not correct. If we count gravity as a force, then it is pulling on the ball just as much at the peak of the parabola as anywhere else, and once the ball leaves your hand gravity is the only force on the ball (leaving out air resistance); your hand doesn't magically exert force on the ball once it's thrown.

If we do not count gravity as a force (which is the approach taken in General Relativity), then there is no force on the ball at all (leaving out air resistance) once it leaves your hand.


Let's talk about pedantry for a minute. Did you notice the comment I was responding to? It was an individual who thought orbit had something to do with escape velocity. Like many people he probably thought that orbit was about 'escaping' Earth's gravity and then just floating in 0g. In other words he knows nothing about orbital mechanics and, most likely, next to nothing about physics in general.

There is no vernacular in my post. When I use the word force, I am stating it in a purely colloquial sense. And in this regard everything is completely cogent and clear description of the forces (har har) in play. By contrast look at the top post. It provides a couple of sentences along with a link to Wiki for further elaboration that immediately jumps into orbital mechanics, assuming an understanding of delta v, etc. There's nothing wrong with the comment in and of itself, but it's an absolutely awful comment in regards to the audience it's talking to.

And I think this pedantry a big part of the reason that so many individuals are completely scientifically illiterate. Most of all science is relatively simple, but one of the biggest issues is vernacular. And indeed within a field there is extremely good reason for this vernacular. It is not only vastly more concise than trying to obtusely explain every single concept from the ground up, but it is also more precise. Do I mean force? Do I mean momentum? Speed? Velocity? Every concept is entirely different, but in the world outside outside of the field -- none of this matters. Theories are just ideas, speed and velocity are same thing, and so on.

The point of this is, do you think my post would be clear and accurate in what it is understood to mean from the demographic that the message was directed at? I think the answer is absolutely yes. And the casual use of terms that have more precise meanings within a vernacular is in no way going to mislead them as to the meaning of what is said. Far from it, in my opinion - using more appropriate terminology is likely to lead to a less elucidating post!


> Did you notice the comment I was responding to? It was an individual who thought orbit had something to do with escape velocity.

Yes, and did you notice that I didn't object at all to the part of your post that corrected the "escaping Earth's gravity" misconception? That's because there was nothing wrong with it. I only objected to the part of your post that was incorrect.

> he knows nothing about orbital mechanics and, most likely, next to nothing about physics in general.

In which case the last thing you should want to do is to tell him things about physics that are wrong. Which is why I corrected the wrong thing you told him.

> There is no vernacular in my post.

My objection had nothing whatever to do with your choice of words. You made a factually incorrect statement and I corrected it. That's all there is to it.


I don’t think it was an attack on your use of language. Even if most probably don’t agree that you are helping illiteracy by alternative use of well defined concepts.

It’s factually wrong to say that the net force is zero at the peak, when what is zero, is the vertical speed.

What was questioned was the feeling of weightlessness. You imply that weightlessness is only felt at the peak of the parabolic path. When the ball leaves the throwers hand, the only force, disregarding air resistance, acting on the ball is the force of gravity, until it hits the ground. Someone inside the ball will feel weightlessness all the way from leaving the throwers hand to hitting the ground. There is no special feeling at or around the peak.


You're completely correct. I unintentionally implied weightlessness only at the parabolic peak. And I think what you've said is how you should correct things. Words convey ideas. What matters is not the words, but the ideas. Correct the idea and things are clear, focus on the words and things tend to muddle.


> in this regard everything is completely cogent and clear description of the forces (har har) in play.

Not everything you said, no. That's why I objected. If you want more detail, you said:

> The ball's trajectory will be a parabola. And at the highest point of that parabola the net vertical force on the ball is zero. It's where the force you exerted on it to send it up, and the force of gravity pulling it down eventually reach an equilibrium. Something inside of that ball would experience 0g at the moment when it was at its parabolic peak.

Actually, the net force on the ball (disregarding air resistance) is the same throughout the entire trajectory once it leaves your hand. (Here I'm taking the Newtonian view that considers gravity to be a force.) That's why the ball continuously accelerates downward by the same amount throughout the entire trajectory once it leaves your hand--which it has to in order for the trajectory to be a parabola. The force you exert on it to throw it upward stops as soon as it leaves your hand, so the only force thereafter is gravity. And since the force of gravity is not felt, the ball is in free fall, feeling 0 g, for the entire parabola.

So the part of your post that I quoted was not a "completely cogent and clear description of the forces"; it was a wrong description of the forces. That's why I corrected it.


...throwing a ball... disregarding air resistance it will be in free fall all the way back to the ground. There is nothing special about the peak.


Orbiting a planet is basically free fall with translational velocity. If the earth were flat we would fall down and horizontally and eventually hit the ground.

However the earth is a sphere and the direction of the free-fall constantly adjusts itself to point towards the center of the sphere creating an orbit.

It is literally throwing oneself at the ground and missing.


I have no idea what's up with HN lately. Your comment is completely correct... and downvoted? This site is starting to become more like Reddit everyday.


I thought you just said you didn’t do it only for karma.. And I almost believed you... btw I wish I could do the same...


Huh???


I think tigershark is referring to this nice comment you made a few days ago: https://news.ycombinator.com/item?id=18644724


Yep!


Free fall. Like inside an elevator with a broken cable. Here the aeroplane starts the free fall with considerable upwards speed. That and the horisontal speed form an upward parabola path of free fall.


You could also ride the swings at the park for free. You get a brief sensation of weightlessness at the top.


For customers who want to see the edge of space, your solution provides zero value.

Being weightless can be accomplished on any rollercoaster, a fraction of a fraction of what you are proposing, with no view of space!

Funny to see this as the top comment when it’s so off base.


But for customers who want to experience what it feels like to float around in zero-G, it provides a lot of value. 5 minutes of microgravity and 500 milliseconds of microgravity are vastly different experiences, it’s like comparing skydiving to jumping off a chair (both of which, incidentally, also provide a “zero-G experience” of sorts). No need for the snarky last sentence.


Funny to see the pointless HN snarkiness never dies.


What was your experience for training prior to this sub-orbital excursion? I feel like going to above 1G would give me a heart attack immediately


If you drive a car you can go above 1g when accelerating or breaking, especially with the latter.

Rollercoasters can do over 6g which is about twice the g force for most manned launches iirc.

In fact if you play any sort of ball sports you likely experience jerk movement well above 1g nearly all the time, and you don’t even want to get started with full contact sports like (American) Football.

It’s not just how many g’s you pull but also the duration, the longer it is the more stress it puts on your body but nearly anyone without any major health conditions should be able to experience 2-3g for a fairly prolonged time without adverse effects and much much higher momentary g force than that as long as you are securely strapped.


1g is the strength of the Earth's gravity, so aren't we always constantly experiencing 1g downwards? Like, every time we jump or lift our feet?


You're experiencing 1g most of the time in everyday life, when not moving. When you jump, you're briefly experiencing a few g downward while you push up on your legs to go against gravity, then briefly zero g for the short amount of time where your body does not touch the ground and you actually follow a ballistic trajectory, then finally again a few g upward as you land.


> When you jump, you're briefly experiencing a few g downward while you push up on your legs to go against gravity, then briefly zero g for the short amount of time where your body does not touch the ground and you actually follow a ballistic trajectory, then finally again a few g upward as you land.

You have the takeoff part backwards; you experience a few g upward when you jump. If you're just standing on Earth, you experience 1 g upward, not downward; the force you feel is not gravity pulling down on you, it's the Earth pushing up on you and preventing you from free-falling downward in response to gravity. When you jump up, your legs exert additional upward force.

(When you land, your legs exert upward force again to stop you from falling down any more, so you have that part right, as well as the zero g part.)


Yes ofc, you also experience a momentary g force much higher than 1g otherwise you wouldn’t be able to jump since you need to counter gravity.

You also then experience higher than 1g forces when you land as the deceleration is abrupt.


You don't even have to drive a car, you can ride in one too!


That's what 224g look like when you stop going in circles with your car https://www.youtube.com/watch?v=aVpux5JxqEk


For automotive sports high g (5+) turns are pretty normal there is a good reason why F1 drivers loose like 10 lbs during a race it’s an extremely taxing activity you need to be in insanely good shape and condition your body to be able to withstand those forces for the 1.5-2 hours of a race.


> For automotive sports high g (5+) turns are pretty normal there is a good reason why F1 drivers loose like 10 lbs during a race it’s an extremely taxing activity...

It is an extremely taxing activity, but the weight loss is mostly water.


Yes ofc due to sweat I wasn’t implying that you somehow can lose 10lbs of tissue in 2 hours.


Hard to believe it's not water weight being sweated out. Marathon runners don't lose 10 pounds in a race that is very physically demanding.


It’s sweat, I’m not sure how much sweat marathon runners sweat out during a race, especially since many of them dehydrate before the race to lose some weight but I wouldn’t also bet on a marathon being more taxing than an F1 race its both are very hard activities as driving a formula car takes a lot of strength.

“Believe it or not the driver has to apply over 930kg of pedal load per lap in Canada - an incredible 65,590kg over the course of the 70-lap race - and it’s all down to the Circuit Gilles Villeneuve’s unique blend of high-speed straights and tight bends.“

https://www.formula1.com/en/latest/features/2015/6/under-pre...


It is water weight being sweated out. Largely because it's a very taxing activity.


If you drive a car you will go over 1g, the second you touch the accelerator, because you're already at 1g at rest.


No experience or training is needed. The Zero-G folks have two very clever tricks for making the transition in and out of zero gravity much more benign than you would think. First, the aircraft has no windows, so you can't see how radically you are pitching up and down. And second, during the transitions in and out of weightlessness, they have you lie on your back, so the blood does not rush in and out of your head. It just feels like you're being pressed down onto the floor for a while, and then over a period of a few seconds, the pressure just goes away and you just gently float up. If you've ever ridden a roller coaster, this is much more benign than that.

They also ease you into it by doing a few 1/3 G (Mars gravity) and 1/6 G (lunar gravity) parabolas before going to zero G.


For me 90-95% of going to space would be to look at earth and the universe, so I would never be in the market for a suborbital joy ride, or this. I recognize that for some this weightlessness might be a large part of the experience.


I wonder if there would be much of a market for the zero-G simulation plane experience, where they have faux-windows that are just ultra high-definition video of the Earth/space. I'd have to imagine with the already strange experience of simulated 0G and the quality of video technology these days, it would be hard to tell the difference with actual space flight. Though it would certainly lose the romantic notion of actually being in space.


It was safe enough for Stephen Hawking a decade ago: https://www.newscientist.com/article/dn11730-stephen-hawking...


Take it from a pilot: the average healthy person has no trouble with a few seconds of 5g, even 7g. With a few minutes of training, you can sustain that for a while, long enough for a loop or roll. I'm no marathon runner and had no issues doing 6ish Gs during sustained acrobatics (cuban 8s etc). Fighter pilots have to sustain higher numbers (9g) and remain alert enough to continue fighting, a far higher requirement than being pax/cargo on a suborbital.

FYI, being "fit" doesn't necessarily help. People with higher blood pressure actually do a little better than those without.


For a test drive of sorts, go to a county fair and take a couple of rides on the Gravitron. That's up to 3 Gs for several minutes at a time and safe enough to be a childrens' ride.


Articles like this feel awfully fuzzy when it comes to how they suggest VG is in some kind of "race" with actual orbital companies. I'm just not seeing the path from A to B for VG's current efforts there, and without that I'm also not seeing what their future is at all?

>The company said the space ship's motor burned for 60 seconds, travelling at 2.9 times the speed of sound as it gained height.

So they managed to briefly beat the Concorde (top speed a bit of Mach 2) and are still well under half the speed of the X-15? I mean, good for them I guess but it seems pretty ridiculous to put VG in even vaguely the same game as anybody doing actual orbital work (not just SpaceX or BO but smaller outfits even). Mach 2.9 isn't even 1 km/s, and LEO average orbital is more like 7.8 km/s (and required delta-v for that will likely be at least a good extra 1.5 km/s over that accounting for drag/grav). Yes "space" may start at 100 km as the atmosphere drops sufficiently, but I think what most people think about when it comes to "going to space" and doing something useful involves orbit, even for tourism purposes (orbital space hotels say). The challenges of every bit of it, from delta-v to heating to in-orbit survival is all on an entirely different plane.

Meanwhile with the BFR it looks quite possibly that SpaceX may well drop below $500/kg to LEO, possibly by a lot. They claim to be aiming for $10m a flight which would be more like sub-$100/kg, but I take that as more a long term aspirational goal approaching the costs of fuel a minimal maintenance then anything in the immediately realizable future. But even a conservative guess of more like $40m would still mean being able to get people into real orbit for less money then VG's up-and-down. BO is pursuing similar cost economics, and both are fighting through the very hard R&D work in actually getting scalable long term cost reductions like methalox working right now.

Can anyone explain what if anything about VG's current R&D would actually carry over to a real spacecraft, or what they use case for it would be if it can't reach that? For merely going very high and very fast on Earth low boom supersonic R&D seems more promising, and for actual space, well this isn't it. What am I missing here?


Virgin Galactic doesn't have any orbital aspirations, as far as I know (unlike Virgin Orbit). The biggest change I saw was they floated the possibility of actually traveling this way- e.g. London to New Mexico or somewhere. But that was awhile ago, I haven't seen any kind of that talk. I think especially since the accident, they've been focused on just doing these suborbital up and down trips and trying to make them a regular commercial activity.

Anecdotally, people in the space industry don't seem too thrilled with VG. This type of ship was great for the X prize, but it remains to be seen how robust it is. Some of the test flight footage has looked almost unstable. Also their hybrid motor approach (solid & liquid fuel) was said to have gotten all the drawbacks of both approaches with little benefit.


Thanks for the reply, that was my rough impression from eyeballing it but the article certainly talks quite optimistically and I'm not at all an expert.

>The biggest change I saw was they floated the possibility of actually traveling this way- e.g. London to New Mexico or somewhere

Yeah, that definitely seems like a wild thing thrown out, particularly given research like the X-59 QueSST NASA is doing [1]. I can't see them possibly competing successfully with an air breathing supersonic aircraft capable of legal overland flight in terrestrial transport, so there's a squeeze from the bottom. And even from a joyride and "I've gone to space!" angle it doesn't feel that compelling vs actually going into orbit for a similar price (or less!). So it seems like a dead end, albeit a cool one, but also a significant amount of money just for that given the context of the times.

----

1: https://www.nasa.gov/mission_pages/lowboom/index.html


Free fall. Like inside an elevator with a broken cable. Here the aeroplane starts the free fall with considerable upwards speed. That and the horisontal speed form an upward parabola path of free fall.


“Can anyone explain what if anything about VG's CURENT R&D would actually carry over to a real spacecraft,”

Why do you limit it to current R&D?

Build profitable “space” business. Make it cheaper, scale it up, reinvest to grow company, more R&D, ... trips into orbit, around moon...

Maybe VG never does but venture capitalists see a market and invest in more space ventures.

Lindbergh crossing the Atlantic sparked the next generation of flight.


>Why do you limit it to current R&D?

Because if all their current R&D is 100% worthless towards their future business (if any) then they aren't actually building any engineering fundamentals right now and might as well be starting from scratch when they need to pivot. It takes many, many years to build up to orbital flight, and everyone starts building that experience and capability at a smaller level. So it's very important if that "smaller level" actually is building towards the next step. Blue Origin for example has been doing a lot of suborbital work with New Shepard, but that is clearly directly building towards full orbital+reusable, they've been building their capabilities wrt vertical landing, scalable engine work, etc.

But if VG's hybrid engine and entire carry/plane concept is simply a fundamental dead end (because it will never have an acceptable mass fraction or hit orbital delta-v reqs or be able to handle orbital reentry say) then most/all of their current R&D is effectively being flushed down the drain. It's not building towards anything new. And that's ignoring whether it could possibly be competitive against what the others are doing.

>Build profitable “space” business.

But what business? Sounding rockets don't match this at all, point-to-point transport doesn't look like a real case for it either, and it also can't do space tourism, just joyrides. But it doesn't look like it'll even be able to do joyrides very well compared to competitors, nor more cheaply.

>scale it up

Some things don't scale up, particularly in rocketry. There is no escaping the rocket equation.

>trips into orbit, around moon

The problem is that from the looks of it not only is nothing they're doing capable of that, it will never be capable of that. I've done some more reading since my post and the hybrid engine concept really just looks like a dud. Their whole plane thing represents a huge amount of wasted mass and extra complexity too.

And again: there is competition here now. If this was all in the 80s/90s yeah it'd be more interesting, even if everyone concluded they'd need to start over from scratch to make a real orbital rocket perhaps there really would be a decade of joyride potential or odd niche uses or something to experiment with. But not against the likes of SpaceX or Blue Origin.


There's no clear path from their current style of rocket to "trips into orbit, around moon". It's dead-end tech - VG going orbital would require either a totally new vehicle (for which little of the current one's work applies) or buying rides with something like SpaceX.


Correct. I never said there was a direct path. I said there might be a profitable path.

There wasn't a direct path from search to self-driving cars, for example. Google makes its money with search ads then reinvests.


> There wasn't a direct path from search to self-driving cars, for example.

Google went in the self-driving car direction only after a) search became wildly profitable and b) search expanded to things like mapping, street view, and heavy investment in AI.

VG isn't in a similar situation - there's little reason to believe suborbital rides for tourists is going to be raking in billions of dollars of cash.


Here I dug this up from 2006.

https://www.space.com/3097-virgin-galactic-anatomy-business-...

There’s probably more. I’ll leave the rest as an exercise for you.

I’m not sure why you can’t use your own imagination. I can easily see this being a catalyst for many other businesses.


That article proves my point pretty well - they were talking about commercial operations starting in 2009. It's almost 2019 now, and they haven't had a single commercial flight.


That’s because someone got killed in the test flight 4 years ago.

Manned space flight is dangerous and progress is slow. I explained this 4 years ago:

https://news.ycombinator.com/item?id=8540723


> That’s because someone got killed in the test flight 4 years ago.

At which point they were already five years behind schedule.

> Manned space flight is dangerous and progress is slow.

Yes, which is further evidence for my "maybe suborbital tourism won't be super profitable" argument.


>suborbital tourism

Is this actually even a real possible thing? "Tourism" is actually pretty well defined since governments and industry take great interest in it, and generally that definition is something along the lines of:

>"The activities of people traveling to and staying in places outside their usual environment for more then one day and less then one consecutive year for leisure with no compensation from the destination."

That effectively matches common sense: someone is not a tourist if they're just going somewhere local, nor a tourist of City X if they're connecting through a City X airport and have a few hours layover there, and if they flat out move somewhere for a year+ (or even a few continuous months in many jurisdictions) then they're into "resident" territory which has different implications as well.

I don't think spending a few minutes somewhere is tourism, it's at most a joyride from the actual place that person is staying. I guess a suborbital near-space habitat might in principle be possible, but I don't think those could ever reach space? I think the highest high-altitude balloon ever remains BU60-1, which got to 50-someodd km. Which is impressive but far below 100km. Humans have reached 40+km with a balloon, so real mass is possible to lift but I haven't crunched the math on how ginormous a balloon would be needed to support multiple people for any significant time period. And would a rocket plane actually be worth using for a rendezvous there anyway?

All of which is kind of fun and cool to think about, but also to say that it's hard to see a case for this.


"Space tourism" is the general term for these things.


We have no idea. They were shooting for 50,000 tourists in 10 years. They have other business ideas.

My point is that people are dismissing the entire VG project, while I see it as forward progress, which could easily be a catalyst for many other possibilities.


Great article, but I don't think that Virgin Galactic is really in the same market directly competing with the likes of SpaceX or Blue Origin. There is a place for all three, but Virgin Galactic is just about LEO space tourism. SpaceX's stated mission is to make humans a multi-planetary species and start a mars colony. Slightly different things.


No, not quite right. VG is in suborbital tourism business - their current technology allows only short hops to Karman line or so. To get to LEO one has to have a substantially more capable system, here SpaceX with its crewed Dragon would be front runner.

On the other hand, VG is much closer to starting offering suborbital rides than SpaceX is to starting offering interplanetary manned flights.


Aaaaaaaand you still proved my point, which is that they're not really competitors at all, unlike what the article says!


It is different but very important.


There is lots here about how far short this falls, vs. a real launch. I don't think anybody has mentioned that the rocket is basically full of powdered rubber and Oxy detergent. You would not be impressed by the odor when you get out.

That, and the amount of pollution it dumps into the upper atmosphere is embarrassing. Not so bad, that way, as the old space shuttle with its strap-on boosters, though. Hydrogen-fueled rockets are the only non-embarrassing way to reach Earth orbit. (H2O2 is OK, but no one uses it for that.)


Arca Space advertised the use of hydrogen peroxide, at least for some of their launches a while ago: https://en.wikipedia.org/wiki/ARCA_Space_Corporation


See also Ignition, by John D. Clark.


This should say "space". It's very impressive still. Space is usually defined to be defined as starting at 100k altitude, when the atmosphere peters out, also called the Kármán Line. This only went to 60k. https://en.wikipedia.org/wiki/Kármán_line

Update: 82k. Sorry, the article I looked at first said 60k, that was wrong.


The US definition of "the point where space begins" is 50 miles (80 km) above sea level, though this was mostly to eliminate an inconsistency between the NASA definition (which was the Karman line) and the USAF definition (which was 50 miles).

Either way, it a fairly arbitrary point in a continuous gradient of decreasing atmospheric pressure that makes an even base-10 number in the predominant unit of measurement, so I guess you can pin this on Americans not using the metric system.


The first line in the article says:

> The firm's SpaceShipTwo passenger rocket ship reached a height of 82.7km, beyond the altitude at which space is said to begin.

Well above he 60km mentioned.


sorry, you are correct, 60k was incorrectly listed in the article I looked at.


km, not k


I read it as 82k meaning 82 thousand meters (k used often to mean thousand and altitude is often measured in meters).


My Australian relatives say "it's about 50 kay" to describe driving distances, for what it's worth.


50 kilomiles?


they could've said "kj" and it still would've been clear from context.


It would also still be incorrect...


The fun thing about Virgin Galatic is that they already have all their crew/human support tech working, and have been flying with humans for years.

All they need to do to be the first private company to put a human in space is just choose to burn their rocket a little bit longer than they have already...

SpaceX and Blue Origin totally have the theoretical capability to put a man in space anytime now - Blue Origin has flown dummies to space, and SpaceX could fly a suborbital flight with their current Dragon capsule even if it wasn’t up to NASA human standards.

The biggest issue at this point is just cost vs bragging rights. SpaceX would have to pay so much more than the other two, that I would guess they will just wait to claim the first private orbital man in space crown.


I'm confused, has Blue Origin demonstrated orbital capability and I missed it? I thought SpaceX and Rocket Lab were the only private orbit-capable launch providers.


I’m talking “Alan Sheppard” man in space, not “John Glenn” man in space. Suborbital. Blue Origin can do that any time they want to risk it.


> just choose to burn their rocket a little bit longer than they have already...

Virgin Galactic would need roughly 10-15 times larger rocket to put human in the lowest orbit. They are not planning to do that and their system is not planned that in mind.

Space is not far. Space is just one hour drive with a car if you drive directly up. Getting to orbit of the same altitude is 10 times harder and that's the business where SpaceX and Blue Origin are.


"Getting to space is easy. It's not, like, something you could do in your car, but it's not a huge challenge. You could get a person to space with a small sounding rocket the size of a telephone pole. The X-15 aircraft reached space just by going fast and then steering up. You will go to space today, and then you will quickly come back. But getting to space is easy. The problem is staying there." - https://what-if.xkcd.com/58/


> You could get a person to space with a small sounding rocket the size of a telephone pole.

This is in fact the goal of Copenhagen Suborbitals: https://copenhagensuborbitals.com/missions/spica/


I'm happy there is one more company, but, can anyone explain what's their mission apart from "sending dummies to space" ? Is there any potential practical value from that?


I guess testing with relevant weight? They said 2 pilots plus a dummy passenger. If the plan is to take a single person up at a time, then this would allow them to test their assumptions about fuel burn and engine performance with the same configuration.


This is awesome, the ship looks awesome, especially the way it accelerates after dropping from the plane, but...

Reaching space is one thing, staying there is something else.

cue elon re orbital velocity https://twitter.com/elonmusk/status/669131093379956736?lang=...


U r saying u have a lot of money to waste. Donation is better.


Is the reached altitude a first for a private company? I mean, with humans on-board?


This is the first time a space flight from U.S. takes humans to space after the Space Shuttles were retired.


> It did not breach the 100km Karman Line, where Earth's atmosphere ends.

SpaceX, Blue Origin, and a few others have exceeded this. SpaceX regularly sends objects to the ICC, which is ~5-6x higher than what Virgin did.

IMHO, they didn't reach space since they didn't break the Karman line... They just achieved "very high atmospheric flight". It's still quite an achievement, and more than they've done in the past IIRC, but they still have a long ways to go.


Sending objects vs humans is a completely different ballgame, so this comparison doesn't look valid. And Karman's line is not very well defined - see https://www.livescience.com/63166-outer-space-border-karman-....


Didn't Scaled Composites do this with SpaceShip One about 15 years ago?


This article is about SpaceShipTwo, the successor version that was supposed to actually be able to carry passengers


I'd love it if they started live-streaming all the launches.


If I was an editor at BBC, I'd be like—"hey guys, this is VA reaching space, can we get a picture of that thing in space?"


Question, do flights like this generate a sonic boom that can impact those in the area?


The craft is taken to 45,000 feet by a more traditional aircraft at normal speeds and after detachment the rocket engine wouldn't bring it to boom-producing mach speeds until somewhat above that I think, and the atmosphere is much thinner so the effect would be greatly reduced. So no, I don't think so.


What are the big improvements they've made in the 14 years since SpaceShipOne?


Despite the front page on the BBC brandishing this story I feel underwhelmed and I am sure I am not alone. This may be Branson's biggest expedition to date but I don't think it sets the world alight in the way that his previous exploits have done so. In 1986 he captured the Blue Riband for fastest crossing of the Atlantic:

http://news.bbc.co.uk/onthisday/hi/dates/stories/june/26/new...

This was very good for the Virgin/Branson publicity machine and important for the image of his airline and other ventures.

However, much like this new 'Galactic' effort, this was kind of done on the cheap. The Blue Riband had previously been contested in the days before the jet age by very large passenger ships carrying hundreds if not thousands of fare paying passengers. Branson's effort had just himself as a 'fare paying passenger'.

Sadly for Branson the efforts of Musk/SpaceX have downsized the publicity potential for what has gone on here. That time that SpaceX landed two of the rocket boosters was one of the most exciting moments in space thus far, the Tesla 'Rocketman' was also quite crazy. This should have persuaded Branson to throw in the towel on his 'space' ambitions but we all have our pride.

If you really want to see the edge of space then I am sure that if you ask the USAF nicely then they can oblige with a flight on a U2 plane. The view is pretty much the same on this tried and tested plane as what Branson offers with this 'Virgin Galactic' thing, which is far from Sagan's 'Pale Blue Dot' or Apollo's 'Earth Rise'. Top Gear presenters have had been to the edge of space (70 000 ft):

https://en.wikipedia.org/wiki/James_May_at_the_Edge_of_Space

I am sure the Russians could offer similar passage. you could even grease the palms of someone with a 50+ year old English Electric Lightning in private ownership to get you up to 70 000 ft. But nobody is beating a path to the door of those with planes capable of this, to come back to earth and demanding to go that bit higher. Consequently I very much doubt there is a market for Virgin Galactic. Maybe Virgin Galactic will have as much impact as the Virgin F1 team, canned after a few seasons lollygagging at the back of the grid. But Branson seems okay keeping these fun adventures going and good on him for that (even if a few test pilots die on the way or if he himself ends up free falling without a parachute). As billionaires go he isn't a bad chap but I ain't no fan-boy.


> Sadly for Branson the efforts of Musk/SpaceX have downsized the publicity potential for what has gone on here. That time that SpaceX landed two of the rocket boosters was one of the most exciting moments in space thus far, the Tesla 'Rocketman' was also quite crazy. This should have persuaded Branson to throw in the towel on his 'space' ambitions but we all have our pride.

That was the same trip, and probably more exciting than anything since Apollo. Seeing those two rockets landing together before cutting to a dummy in a car blasting out of orbit, all choreographed to David Bowie, it looked like something from a movie.

However back when spaceship-one went to space (not orbit obv) and back twice in 2003, it felt like space was just around the corner. It took over a decade before SpaceX successfully landed their rocket to surpass that feeling.


I'll be interested when they start firing Branson, Musk, Clinton and Trump towards the nearest habitable system.


[flagged]


Please don't do this here.


I'd save my money for a trip in the BFR


Then fell back down. Call me when it's orbital.


It's an orbit. It's just that the perigee is located deep within the Earth. (Deceleration due to sharply increasing frictional resistance is very likely on this class or orbits. This is likely followed by rapid unplanned disassembly.)


How likely is very likely? Can we quantify the chances of rapid unplanned disassembly causing deceleration?


It's very likely a real number.


I also imagine it to be real.


It's also very likely in the set of complex numbers.


headline similar to recent "Nasa's Voyager 2 probe 'leaves the Solar System'"

Similar but different...haha


Free fall. Like inside an elevator with a broken cable. Here the aeroplane starts the free fall with considerable upwards speed. That and the horisontal speed form an upward parabola path of free fall.


Surely the increase of all rocket launches/ships must be having a somewhat substantial impact on Earth's environment?


Whether we ruin the Earth or not it won't last forever. We need to find additional space-fairing vessels capable of sustaining humanity at some point. For now, it looks like the Moon and Mars are the most achievable bets for getting some of our eggs out of this cozy basket.

So...#worth.


Gotta love articles that consist of short-sentenced, one-sentence paragraphs.


Found it ironic that Branson called space 'Virgin Territory'.

There's a very good possibility that we'd be sending ourselves into the dark ages if space debris goes unmanaged. https://www.youtube.com/watch?v=yS1ibDImAYU&




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