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Arabsat-6A mission [video] (spacex.com)
609 points by jacquesm on Apr 11, 2019 | hide | past | favorite | 230 comments

I don't think that most people realise what an achievement this is. This is major, three boosters landing simultaneously and one of them is landing on a moving object in the middle of the ocean. And they will reuse the two side boosters for the next FH launch.

Most people don't even know that this happened. I talk to people about it often and most don't know that there is a Tesla floating in space.

I think most people can safely and happily live their lives without having to know there is a Tesla floating in space.


Where do you draw the limit of what people should know to be happy ?

Why is happiness a factor in what people ought to know?

Humanity just took a picture of a black hole with a multinational telescope array, predicted by decades old math and all that jazz.

All a few (educated) friends had to say is that the image looks like garbage, what is this bullshit on my frontpage.

I was surprised about how upset these reactions made me. But then I figured there must be a multitude of important things of which I do not have even the tiniest understanding or care.

If you’re looking exclusively at happiness, ignorance truly is bliss. The less you know the better.

I flew several thousand miles to be on Cocoa beach that fateful day to witness it for my own eyes. It's one of the things I'm most proud of having accomplished. I cannot imagine what it feels like to actually work on the project.


Being a witness to history?

Nothing to add here except I'm completely impressed as a software engineer and a human. Congrats to all who made this happen -- you have done important stuff.

Watched the video w my 10 year old kid and tried to explain how impressive this is and relate it to my own experiences watching space shuttle launches.

Would you mind expanding on that last part regarding how these launches compare to shuttle launches?

Not to denigrate what's going on now, arguably it's far more important technically and possibly a bigger achievement, but it doesn't _feel_ anything like as exciting as the first shuttle launch. And to be clear, I was pretty pumped to watch the first booster landing and the roadster launch.

Pretty much the whole (western) world stopped to watch it. It felt very much like returning to space for the first time since the end of the Apollo project (it wasn't, but it felt like it), it was such a step change from the previous generation of rockets. This was science fiction in action, it was going to revolutionise space travel. It even looked like a new form of transport, and the speed with which it cleared the gantry was amazing to people used to a Saturn 5.

We taped it off the TV, and I remember going back to watch it again multiple times.

This is more of a commentary on society than anything else. There are much more pressing things happening on facebook these days than autonomously-landing robot rockets.

Maybe, and certainly if we'd seen an unmanned booster land on after completing a successful launch in the early 80's we'd have been very excited, but the shuttle just caught the imagination that bit more. Justifiably or not.

Anyway, the question was, "how do they compare?". Personally, emotionally, they're pretty damn cool, but way less exciting. More so than can be hand-waved away as simply being older and more cynical.

It equates to comparing landing a 14 storeys high broomstick with landing a flying brick.

Both are impressive, but spacex' achievement is making their booster truly reusable. The shuttle required way too much refurbishment to be commercially viable.

These vehicles are also completely different in their purpose so it's hard to really compare, I find them both inspiring really.

Here's a comparison made by everyday astronaut: https://youtu.be/HF69nqY3TZs

Seeing the boosters fly back and land themselves reminded me of watching the shuttle boosters detach and fall away from the shuttle.

The shuttle boosters would parachute and land in the ocean where they were retrieved and could be reused.

Back then, the thought of those boosters precisely flying themselves back to the launch site would seem like science fiction -- now it is science fact.

Just watching that video brought back memories of watching the shuttle launches -- as swish_bob says those were a BIG DEAL back then both for the engineering achievement but also culturally. It was something to admire and be proud of even if your only contribution to the project was "being born in a time and place where people do things like this".

If my memory is not playing tricks on me, when the MTV music channel started (which was also a pretty BIG DEAL in my world back then) they used animations of the shuttle (landing on the moon, I think) as part of their branding because it was hard to get any cooler than the shuttle.

These are much more impressive imo

Landing the boosters. Simultaneously. The entire live web stream, live video from space, the stats and maps, etc

Both are impressive but it different ways.

The shuttle impressive part is that they are landing the second stage, which is an order of magnitude harder than landing a booster.

The Falcon (9/heavy) impressive part is that they are flying a reusable rocket in an way that is commercially viable (which, BTW, is what the shuttle hoped to achieve).

The shuttle was essentially just a glider once you got it out of orbit. Not a very good glider, but still an object intend to "fly".

I think the best analogy I've heard for the boosters is that it's equivalent to throwing a pencil over the Empire State Building and having it land on it's eraser.

I think most people are just focused on other things. I'm sure there are plenty of other great achievements we never took time to appreciate. The discovery of CRISPR is probably one of those things. We just have a different focus. Life moves on...

* Two boosters landing (mostly) simultaneously, the center core landing later downrange due to the higher altitude and velocity it commenced reentry at

Two boosters are intentionally offset a bit. Don't remember the exact reason but something about different radar signatures to tell them apart.

They do this to prevent the two boosters from interfering with each other's guidance systems, which I believe uses radar. I recall from the first FH launch that the two boosters landed almost simultaneously and that was a fluke, they wanted to land then staggered a little bit. Thankfully the guidance systems still did their jobs.

the fairings were also recovered, and will be reused. (even though they landed in the ocean)

I do think most people realize it. When I’ve been around the country, when SpaceX launches come up, people are amazed by it.

> people are amazed by it.

Being 'amazed by it' isn't equivalent to fully realizing what SpaceX's achievements imply: specifically tracking the progress of SpaceX means counting down the years until you can buy a ticket to Mars.

Do most people realize that these launches are primarily done to create Mars colonies? Do most people realize that the goal of SpaceX is to terraform Mars into a planet livable like Earth? Do most people really grasp all this?

I haven't met a single person (aside from existing friends) IRL that understands any of this. It seems to be mostly "cool, rockets!" to most people - none of the full understand of what each success is to SpaceX: money in the bank for Mars development and experience launching rockets to colonize space.

The vertical landing via rocket is to make it easy to launch and land on any solid surface in the solar system. Do most people realize the impact of this? I would be shocked.

The only thing that kind of annoys me in the back of my mind, is that these guys are aiming to save humanity, but the average Facebook engineer figuring out how exploit users better is probably being paid 2-3x as much as the average SpaceX aerospace engineer. But that's what the free market is rewarding right now.

Save humanity? From what global warming? Global warming is nothing compared to Mars. If we can terraform mars into a beautiful landscape then climate change isn't really an issue on earth...

Going to Mars for scientific research would be an incredible step forward for man kind. But the feasibility of space still holds a lot in question. It is exciting, but let's not call it "saving humanity".

Save humanity from an extinction level event. Think asteroid impact or global nuclear war rather than climate change. Musk has been pretty explicit about his intention to make humanity a multi-planetary species. [0]

[0] https://www.liebertpub.com/doi/full/10.1089/space.2017.29009...

What nightski is saying is that achieving a truly independent colony on Mars, which can survive the destruction of Earth, is much harder than just putting people there.

Mars might an interesting playground for testing climate engineering, since it'd be hard to mess it up more than it is now. That said though, it's hard to imagine fixing things like the lack of atmosphere without a lot of investment.

While I agree that less effort should be spent on what Facebook wants to achieve, there are way more engineers that would rather work on space stuff than positions so of course they are going to pay less. So the market is functioning as it should.

"Should" is a subjective moral/ethical evaluation. The market is just functioning as predicted (which is still nice).

do you have any source for spacex engineers salaries vs Facebook ones?

I don't see us terraforming Mars anytime soon.

Also, just FYI, your comment comes across as incredibly elitist as well, which is made even worse because the so-called "implications" don't actually follow from what we saw today, or do so only barely.

Oh I agree, it won't be soon! But that's the real goal of today's launch: to learn more about the technology that will enable the technology to terraform Mars (and to bank money to fund it).

I think that is lost on most people. There's no point in today's launch for SpaceX if they don't get closer to colonizing and then terraforming Mars. They don't care otherwise - that is the goal.

Edit: Not sure what you mean by elitest, but okay. Every SpaceX launch, including today's, works towards this goal: this is what watching SpaceX launches is about for a lot of people, maybe most who watch.

Your comment sounds like you're calling "most people" stupid for failing to grasp the "true significance" of this launch (but you and your friends, obviously, were able to). I'd suggest tweaking it if that wasn't your intention.

I think the comment is pretty spot on and I also think most people are stupid and they don't grasp the significance of what Musk is trying to do. I don't know the OP but wouldn't mind being his/her friend.

What can be done to get more people to grasp the significance here? Or is this pattern just human nature?

I'm a big SpaceX fan, and I don't think most people are stupid. For more people to care, SpaceX needs to launch more significant payloads. A communications satellite is humdrum. Shooting a car into space is about as cool as dumping a car into the ocean.

Space telescopes, Mars rovers, Moon missions, these are the cool parts. Exploration! If SpaceX lowers costs enough to give of us more of these missions, then people will care. They've only maybe just started to make an impact, with Beresheet.

Sure, not my intention - I think most people don't care. It's not a judgement about them. I just think they don't grasp it because they don't care and that's okay.

There may be a large group that does care, does grasp it, but is skeptical because the claims are fantasy. Consider that terraforming Mars is way harder than terraforming Earth's deserts, and yet even that is not being done. Also consider the little bit of terraforming mankind managed to do since the start of the industrial revolution, and what kind of resources it took to do it. It doesn't really translate to Mars.

I think that fundamentally people are conservative when it comes to new technology. That's all.

If the rocket puts a car into space, we have the ability to put a car into space. If the rocket lands and is reusable and cheap, we have that ability. If we send colonists to mars, we can send colonists to mars.

Until it's done, people won't worry about it or incorporate it into their worldview. Short of offering to help, what's the point in worrying about it until there's something new that I can do? There are way too many things to worry about them all, I just care when a new thing is actually available.

Mars colonization isn't a worry, it's a hope.

We can't seem to manage maintaining this place as a livable planet, let alone a planet we have yet to even retrieve a rock from.

But yes, SpaceX is doing a lot to make spaceflight more accessible, and that will yield many benefits and opportunities down the road.

It is extremely short-sighted, how we have treated our planet. With oil and gas companies lying to the public about their research for 50 years, and politicians intentionally taking stances that we should pollute more (just because we can), the main issues on Earth are around decision making.

It will not be technology that solves climate change; it will be a reigning in of externalities, correctly pricing pollution into corporate development and taxation, and the recovery of truth into politics and decision making.

It should be common knowledge that most corporations are trading our long-term health for short-term profits; if only the corporations could wait 5-10 more years for profits, they could be had sustainably for centuries, rather than all in a burst today.

We need better decision making on Earth - and better technology. But it's hardly SpaceX's fault that we haven't solved our Earthly crises yet.

I guess that's why Musk also has a company doing electric cars and solar roofs.

Do most people realize that these launches are primarily done to create Mars colonies?

Sure, in the same way that I'm building the next Facebook because I've registered the domain name I'm going to use.

Sorry, but no. Musk said he wants to go to Mars and thus he founded SpaceX (and the other companies). Musk has already delivered - it's not there yet but you can't deny the guy's wide-ranged success in his mission.

I went to (a lot) of school for science and engineering. I’m on the internet all the time. I’m hip to this. I know I should be blown away by this kind of thing, but this, and the recent black hole pic for that matter, don’t do it for me. A really good movie, band or even a show like rick and morty will. I’m terms of science/engineering - the theoretical work or ingenious experiments do it for me. I guess what really amazes me is pure novel/creative thinking. The application of that thought is just a lot of work - and unless it’s s moon landing or nuclear fusion or curing a major disease or something like that I’m just like whatever.

I think most people realize it thanks to the very good communication by SpaceX.

Personally, from a technology standpoint, I am not that impressed compared to what we have done in the past when it comes to space exploration. Moon landings, space shuttle, Mars rovers... The current state of rocketry all but highlights how awesome it was before.

The awesome part about SpaceX is not that their rockets are the best humanity can do. What's awesome is that it may very well make the first reusable rockets that make economical sense. Unlike NASA in the past, they don't have unlimited money, they are a private company, and even if they have help from the US government, they have to work with a budget.

If anything the achievement is not the rocket itself but how it creates a regain of interest in rocketry, both popular and economic. I mean, our workhorse rocket (Soyuz) dates back from the 50s, and all of the awesome (and too expensive) stuff like the Saturn V and shuttle are now lost.

> Personally, from a technology standpoint, I am not that impressed compared to what we have done in the past when it comes to space exploration.

This is possibly the most Hacker News comment I have ever seen.

It's been 62 years since the first spaceflight. There are currently six people in space.

62 years after the first flight, world-wide air travel numbered a billion passenger-miles per day.

So, pardon me, but the pessimism about space progress is fairly justified.

62 years after the first flight would have been 1845. The Montgolfier brothers flew in a balloon in 1783.

It's entirely possible that chemical rockets will turn out to be the "hot air balloon" of space travel. Whether this perspective increases or decreases your pessimism is up to you.

We wouldn't have many passenger-miles in air travel either, if we threw away the airplane after a single flight. Or even part of the airplane.

Hence the focus on reusability by SpaceX and Blue Origin.

Considering the havoc air travel is causing the environment, we should aim away from mass space travel for the foreseeable future.

Many people overestimate the environmental impact of air travel.

It's "only" about 2% of global energy consumption. Not nothing, but also not that significant. There are much bigger energy wasters that can be targeted.

It's the other way around unfortunately, people underestimate it: The effect of air travel on global warming is much higher, due to emissions effects in the upper atmosphere. Eg WP says 'Emissions weighting factor (EWFs) i.e., the factor by which aviation CO2 emissions should be multiplied to get the CO2-equivalent emissions for annual fleet average conditions is in the range 1.3–2.9'

And air travel is growing at a steep rate because air travel has gotten so cheap and big populations in developing countries take up air travel.

This mentality predates HN.

“No wireless. Less space than a Nomad. Lame.” Rob Malda, on the iPod at its release in 2001.


All it needs is a McKayla Maroney "not impressed" meme and it'd be complete.

Random person with no creds here. I’m not impressed.

> Unlike NASA in the past, they don't have unlimited money

That money ran out, thus also proving limited.

I wonder what sparked interest in rocketry in the USSR enough that they launched Sputnik, etc with no immediate military benefit. As berated as communism is, they had vision enough to see past the capitalists in that moment...into space.

I think you're underestimating the military benefit of being able to launch something into space...

Indeed, it was always a military application, v-1, v-2, launching sputnik was demonstrating the ability to put a warhead anywhere on earth. It was called the 'red scare' for a reason.

Controlling the higher ground is always a military advantage.

lol. you're right.

All the early Russian and US space launch systems were modified ICBMs. The US started their ICBM program immediately after WW2 the same as the Russians. It’s just that with the US developing the atomic bomb firsts, Russia had a stronger incentive to get a really big technological ‘First’ of their own.

I’m not in any way denigrating the Russian achievement, but it’s not as though the US had no rockets of it’s own at the time and the military benefits were clear to both sides.

I don't think that most people realise what an achievement this is.

What makes you think that?

Because those of us that are paying attention can barely fathom how awesome this is. A case of "the more you know, the more impressive it is".

Sufficiently advanced technology is indistinguishable from magic indeed. They make the landings look trivial.

Ridiculously bad-faith.

I must have misunderstood your comment.

The original statement: that most people don't realize how awesome it is.

At face value, I've observed that less than 50% of people I know are even aware this is happening. So on that observation alone the statement is true. Among those that do know, when I've explained that there are something like 10 dimensions to solve (x/y/z velocity, x/y/z position, pitch/roll/yaw, and time) and that you have to solve all of them using only 4 inputs (lower booster, and 3 lateral boosters), they are more amazed.

In my experience, almost everyone I meet has the potential to be more impressed by this event by just learning a bit more about it. Therefore "most people don't realize how awesome this is".

So they have an idea how awesome it is, but you don't think they think it's awesome enough?

you have to solve all of them using only 4 inputs (lower booster, and 3 lateral boosters), they are more amazed.

I thought they used those grid wings on launch, too.

Ah, I see the gatekeeping angle. Fair enough.

Gatekeeping aside, the point stands that I, and others, appreciate it more as we learn more about it. Which is pretty cool.

What about the core booster? Would that be reused too?

Here is the reuse record so far: https://www.reddit.com/r/spacex/wiki/cores

To be fair it is only a small, incremental improvement to the first FH launch which came within a whisker of doing exactly the same thing, if only for a small lack of fuel on the way down.

I can't think of anything that beats the dual hoverslam for cool factor. What a breathtaking sight! Mad props to Elon and the team at SpaceX for getting the hat trick.

Agreed, it is pretty epic. It is one of those things that really impresses how far ahead of the previous generation launch systems this can be.

Now it will be interesting to watch how "low cost" commercial heavy launch capabilities will be used. I know they are working hard on the the BFR but there is money to be made here that I'm sure at least Gwynn Shotwell is looking to take away from ULA and others.

The sonic booms were lovely as well! Gives you somewhat of a sense on how fast they were coming down.

all 6 of them!

Each booster generates 3 distinct "booms". IIRC the causes of each are slightly different, but it's nutty hearing it in person!


One is from the engine bell, one from the widest part of the body by the landing legs, and the third is the grid fins.

growing up watching flash gordon, buck rogers, to thunderbirds, and more, it feels as if all the Saturday morning TV is now real.


Everyone has their rationalizations, but to me the transport of a weapon is different from designing a weapon, which is different from firing a weapon. Each may draw the line as they see fit though.

Agreed. And in this particular case, they're not even transporting weapons, right? I don't see this as being too different than a paper products company supplying notebooks to the military.

In this case they're not doing anything for the military. This payload was a commercial communication satellite.

SpaceX has only done a small handful of DoD/NRO missions.

...and in each of those cases, they were not weapons.

Just the devices used to choose targets. It seems like splitting hairs when you effectively don’t build guns, you just build gunsights to use a metaphor. Note that I’m in favor of supporting the military, but I’m not in favor of pretending that support however it comes about doesn’t ultimately connect to killing people.

I mean, GPS, too, right? I think you've exaggerated the definition to well beyond reason.

While GPS can be used to target bombs, it can also be used to target many other things, like cameras and airplanes and helicopters and containerships and taxi rides. Simply because GPS is useful in war does not make it a weapon of war.

Spy satellites don't help industry or commerce or transport or safety or medicine. They solely help those who kill hundreds of people for a living.

Spy satellites, due to their very restricted scope of usefulness (and to whom they are made useful), are weapons of war. We'd be having a different discussion entirely if their outputs were livestreamed to the whole planet (like the GPS signals are). Those that run them don't permit that, because then they wouldn't be quite as useful for committing lots of murders.

Yes, GPS too. It is after all what puts the “smart” in bombs. Again, this is something I broadly support, but I’m not in denial about it.

I'm a grown man and I still cry every time a booster lands successfully and every time a rocket clears the tower.

What a thing of beauty.

Watching the successful touchdown of the 3 boosters and subsequently tearing up had me feeling like maybe something was wrong with me, but I’m glad to hear I’m not an isolated case and that this achievement was indeed packed with emotion

Grown men are supposed to cry

Crying is nominal.


(In case some don't get it, pay a visit to r/SpaceX on Reddit.)

Birth of a child. Death of a dog. Epic wins.

Yep, checks out.

or maybe... whenever they feel like it?

Yeah, but we can agree that among certain community there can be a shared "whenever they feel like it".

haha, my wife automatically handed me the box of tissues when i put on the spacex live stream just now..

I'm emotionally destroyed today. Betrayal and arrest of Julian Assange last night (Australian time) and successful second launch of the Falcon Heavy this morning. Feeling greatly upset while also feeling joy from two very different but simultaneous events.

p.s. not meaning to start a derail about Assange which would be off-topic

Same here. Watching this in the office and thinking to myself "don't cry, please don't cry"

It is pretty emotional, I admit to some tears as well. Then a thought about joining the SpaceX team.

I am not alone on that then!

I tear up as well, it's an incredible, beautiful display of engineering and physics.

found my people

It's also a beautiful display of human ambition and looking to the future :)

Just watched the boosters come down on the Cape from near Cape Canaveral National Seashore. Amazing to watch be able to see the separation, boostback burn and landing burns with my own eyes. Beautiful and eerie sight.

Lucky you! Consider me slightly jealous, I have to do with the youtube feed, but I have yet to miss a launch. This one kept me up way past my bedtime but it was so worth it :)

I took my kids to see the demo launch and they said the rentry burns looked like evil eyes but to me they looked like half an x-wing. ;) everyone must see a live launch.

I have a question:

It seems to me like the rocket lifted off quite quickly, like the acceleration at first (right at t=0) was very rapid compared to other launches I have seen, especially launches with big rockets.

Is this because it's a satellite that can take higher G's? Is it because they're launching a payload with low mass so it has low TWR? Do these engines spool faster than the engines used in other rockets (like the ones used for Apollo or the space shuttle)?

Or, am I just incorrect that this one is faster...

Jealous of everyone who could witness this up close, as usual.

Falcon Heavy does indeed lift off the pad faster than many rockets (it's even faster than the single-stick Falcon 9). This is because of its higher overall TWR (since the two side boosters are functionally Falcon 9's without the mass of a second stage and payload). Another rocket that really leaps off the pad is Ariane 5 (once the SRBs light at T+8sec).

Generally speaking you want to accelerate as quickly as possible in the early stages of the flight in order to reduce gravity losses (every second you spend going "up", the more energy you have to spend fighting gravity). There are other factors involved here though (if you get going too fast in the lower atmosphere the losses due to drag start outweighing the savings, etc).

The spooling time of the engine doesn't really matter here, because the launch clamps don't release the rocket until the engines are all up and running and healthy, so when T-0 hits, the engines are already at full thrust.

> Generally speaking you want to accelerate as quickly as possible in the early stages of the flight in order to reduce gravity losses (every second you spend going "up", the more energy you have to spend fighting gravity).

This doesn't really make sense to me from a simple dynamics perspective. Why does time matter, unless efficiency comes into play somewhere?

I typed up a long explanation... then looked up the Wikipedia page to confirm the usage of a term, and realized it has a much better explanation, so... here's that...


Yup, that cleared it up. Thanks!

A really stupid simple way to think of it is --

Imagine you're hovering a hundred feet off the ground. You still need to be burning your engine at a full g, but you're not going anywhere. You're spending LOTS of fuel for zero movement. Now imagine you can only burn at 1.01 g; you will VERY slowly start moving upwards, but you'll be spending a colossal amount of fuel for the same result.

Now imagine instead you're burning at 3g; suddenly you're actually accelerating quite quickly, and you're overall burning much less fuel to go the same distance.

a really good way to visualize this is to build some fat, awkward vessel in Kerbal Space Program that has a thrust-weight ratio of only 1.2 or thereabouts, and use mechjeb to watch the data during launch. It'll eventually get to orbit (enough struts and boosters will do that, in KSP) but you'll see how inefficient and slow it is, how much time it spends in the lower atmosphere, compared to a properly optimized rocket.

Yeah, I forgot that staying in place in the air requires burning fuel :/

How I like to understand it instinctually is: When you're going up, gravity is working against you. The more time you spend going up, the more time you spend with gravity working directly against you.

Once you're out of the atmosphere and into the "over" phase, you're not fighting gravity, you're just trying to increase your lateral speed enough that the earth's falling away from you faster enough than gravity's pulling you toward it.

Or you can think of the limit case: as your acceleration away from earth goes to zero, your energy spent fighting gravity in order to avoid hitting the ground goes to infinity.

This one has about 10% more thrust than the previous Falcon Heavy launch and approximately the same weight, so it's going to be accelerating faster than last time. And as others have said, you have 3 cores but only one upper stage, so you'll have higher Thrust to Weight ratio than a Falcon 9.

The Falcon Heavy has three times the initial thrust, three times the booster weight, but only the normal amount of second stage weight. Going by numbers from Wikepdia that don't count the payload the normal Falcon 9 has a TWR of 1.41 and the Falcon Heavy has one of 1.64. So it should be lifting into the air about half again as fast.

The payload weight will make a small difference but it'll be pretty small to the overall weight in any event and not make a large difference. Arabsat-6A is just 6 tons compared to a total weight of 1426 tons.

For reference, Falcon Heavy's max payloads are 63.8T to LEO and 26.7T to GTO, so today's load was quite light. ArabSat would actually have (just) fit in a regular Falcon 9 as well.

Those maximum payloads are in expendable mode, though. SpaceX wants to reduce expendable launches as much as possible. For a reusable FH the numbers are substantially lower and the satellite might not have that much more mass to still fit.

So, just going off of what's on SpaceX's website[0], Falcon Heavy generates ~5 million pounds of thrust at liftoff, and weighs 3.12 million pounds. Max payload to LEO is ~140,000 lb That implies that acceleration at liftoff is somewhere between 1.53 and 1.6g, which would be fine for humans.

Further into the launch, I assume it's accelerating way faster than what humans can handle, but human limits wouldn't explain what it looks like anywhere where you can use the ground or apparent distance as a point of reference for speed and acceleration.

According to the Source of All Truth[1], Saturn V generated 7.6 million pounds of thrust, and had a launch weight of 5.1 million pounds. That means that, with no payload, it would accelerate at 1.49G. Meaning that the maximum possible acceleration is less than what you'd get with a fully loaded Falcon Heavy.

But that's not enough slower to be clearly visible. So I got no idea. Maybe it's some sort of perspective thing, or camera angles?

[0]: https://www.spacex.com/falcon-heavy [1]: You can figure out the URL

The maximum axial acceleration of a Falcon launch (in either configuration) is +6g[1]. That's certainly uncomfortable (and a manned flight wouldn't accelerate that quickly), but it's not beyond the limits of humans to tolerate (particularly for a short duration near the burn out of a stage).

[1]: https://www.spacex.com/sites/spacex/files/falcon_users_guide...

I think FH acceleration off the pad is slightly higher than F9. Makes sense since there's 3x as much liftoff thrust but generally the liftoff mass is not 3x that of a F9.

And they just had confirmation of a good orbit on the payload, which means every single part of this mission was a success.

Congratulations to the team at SpaceX!

Did anyone else notice the object flying by @ 54:26? What was that? Looked bigger than a piece of dust, was moving much faster than the upper stage and payload. Is that normal? Did it pose any risk?


Interesting find! Earlier in the feed you can see a solid piece of oxygen [0] bouncing off the engine. The particle you mentioned is going past the spacecraft (forward), so I can't see it being solid oxygen. My guess is a piece of dust that is being illuminated, and the camera is picking up the reflection but is blurry, making the particle look bigger than it actually is.

[0] https://youtu.be/TXMGu2d8c8g?t=2729

It happens right as the spacecraft is recoiling from the separation impulse, so I'd guess it's something coming off from the top of the stage and passing by the camera.

Whoa - thank you for pointing out the solid oxygen. That is mind-blowing to me! Super cool!

They explained at another point in today's stream that the pieces you see flying around are solid oxygen from a drain on the second stage. Totally normal and you see it on every one of their launch streams!

A couple inches to the left and that dialog would have been comedy gold :b (Although more seriously, I'll speculate that it looks larger than it is because it's reflecting a lot of light).

right after main booster of the second stage ignited a part of the ring came off. there is stuff that comes off every launch I've seen.

That's a stiffening ring. It helps the nozzle to the second stage engine keep its shape while the first stage is firing.


Hah, they did it! 3 Landings (2 side boosters and the center core). What a sight!

The third one landed on a drone in the middle of the ocean. Call me crazy but wouldn't that be a moving object?

Insane. All 3 rockets.

The drone ship does what it can to be as stationary as possible but the swell will always move the platform to some extent so the ocean landings are a lot more impressive than the land based ones.

Keep in mind that the boosters flip around and initiate a burn to get back over land. As far as i'm aware, the core maintains a primarily ballistic trajectory and thus lands out in the ocean.

The boostback burn is a hell of a thing too, there was a Space Shuttle contingency plan called RTLS that was essentially the same thing. IIRC one of the commanders described it as "an unholy act of physics". This is quite similar, albeit with much less mass.

Yeah, the major complication with the STS RTLS option is that the Shuttle had to keep the external fuel tank until after the return burn was completed (since the shuttle itself carried no propellant for the main engines).

Scott Manley did a video a few years back explaining how this return profile works (and attempting to fly it in Orbiter)


Also (IIRC) you wanted the external tank to have as little remaining propellant in the main tank as possible, to facilitate separation without impacting the tank. Which meant that your burn times didn't really change when aborting, which is not a common feature of spacecraft abort systems to say the least.

And there was no way to eject the SRBs early, either. Once those lit, you were in for a ride...

The space shuttle had far more black zones in its launch profile than would have been acceptable in the Saturn program, or any manned program since.

Yeah, the tank had to be empty before it could be dropped (so the RTLS profile actually involved continuing away from the launch site for a while in order to burn off all the fuel without overshooting the return).

I've always been curious as to why that drone is so damn tiny compared to the rocket. Wouldn't make it slightly larger reduce your chances of missing the platform, or are they just that confident about their accuracy?

As someone noted already, the drone ship isn't small. Also, accuracy didn't seem to be a problem in any if the landings, as long as nothing unexpected happened, like fuel running out. Someone ok r/spacex recently compiled a diagram of landing locations: https://i.redd.it/yra4ipgl3ln21.jpg it doesn't look like they need the target to be bigger.

The drone ship is almost the size of a football field.

Huh, you're right. It's really hard to get a sense of scale.


It’s just a practice round for the startup of regular New York to London service.

For anyone searching, the timestamp is 27:30

FH is reliably going up and coming down, which is incredible: my attention is barely here since they are building multiple Starship Hopper test articles in the open fields of south Texas. [1, 2]

The increasingly most likely scenario with SpaceX and BO is that we'll have self-sufficient Mars colonies and space colonies in the next few decades. The funding is economics-based this time around rather than taxes and government projects, making it less volatile and less likely to be cancelled. Pumped!

[1] Tethered first test: https://twitter.com/elonmusk/status/1114390314565787648?s=19

[2] https://forum.nasaspaceflight.com/index.php?topic=47730.msg1...

> we'll have self-sufficient Mars colonies and space colonies in the next few decades. The funding is economics-based this time around rather than taxes and government projects, making it less volatile and less likely to be cancelled

Lunar and asteroid support colonies, sure, but what is the sustainable profit model for Martian colonies?

I seem to recall that Robert Zubrin's book "The Case for Mars" suggested selling Martian deuterium to Earth. That idea is tied with "mine the Moon for helium 3" as the least plausible business idea that otherwise-smart people can suggest with a straight face.

EDIT: he also shared this idea in articles.


Deuterium, the heavy isotope of hydrogen currently valued at $10,000 per kilogram, is five times more common on Mars than it is on Earth. Deuterium has its applications today, but it is also the basic fuel for fusion reactors, and in the future when such systems come into play as a major foundation of Earth’s energy economy, the market for deuterium will expand greatly.

Martian colonists will be able to use rocket hoppers using locally produced propellants to lift such resources from the Martian surface to Mars’ moon Phobos, where an electromagnetic catapult can be enplaced capable of firing the cargo off to Earth for export. ...

Is it really cheaper to get deuterium from Mars than it is to refine it from water on Earth?


Fossils. Should go for $100 Mil each.

My personal theory of how this will play out is that Mars will be a shallow gravity well industrial base for solar system development. We take for granted how integral gravity is to pretty much every thing we do when it comes to building stuff. It's not known if there will ever be large scale industrial activity in zero gravity. O'Neil cylinders are a solution, but expensive to start. If you can either mine Mars or process astroidal material there, it's a lot cheaper to get back into space from Mars than it is from the moon.

That only kicks the can down the road a bit: what are the "solar system development" needs that would financially justify a Mars colony?

It probably starts from near-earth work to maintain Earth-orbiting infrastructure - refueling satellites without lugging fuel up Earth's gravity well. Then probably manufacturing in-orbit for similar cost savings on launch. And once there's that little bit of industrial base, the most likely driver of larger-scale industrialization is mining of elements that are rare on Earth and industrially useful (osmium, rhenium, iridium, etc.).

At least initially, I think ticket sales will do. With ticket prices floated for like 20 years before any go on sale, the target price is like $200,000 or so and the idea is that many people will be both willing and able to sell their Earthly possessions and go.

They will produce multiple exports from Mars that are most likely going to be scientific data and software, things that are easily transmittable back to Earth (unlike rocks etc).

I would also imagine the more distant future profit models will be similar to on Earth; people will buy and sell goods and services there, just like they do here. There will be Martians who want to go explore the rest of the solar system, so they will build that tech as well.

I could list more and maybe I will but I gotta run. There are limitless potential sustainable profit motives and economic activities that will happen on Mars; until we go and establish the colonies, we can only speculate the exact nature of them. But given that millions of people are saving their money clamoring to move to Mars ASAP, I imagine there will be millions of ideas for generating income on Mars.

Where there are problems that people have, there will be solutions that people will pay for. And there will be millions of people on Mars - so I expect millions of problems and millions of solutions.

Edit: I imagine sports arenas will be built, and new sports created/adapted for Mars (the moon will surely be popular for this too). There will be Martian olympics and various other games that nobody on Earth can do - but will surely pay $20 to 'livestream' ppv.

I'll keep thinking about possible _differentiated, diversified, and large-scale_ revenue sources for self-sufficient colonies on Mars to consider prior to and during their founding.

Tourism, mining high-value minerals, real-estate speculation, new forms of low-gravity athletics, and retirement communities for people with mobility issues who would be stuck in a wheelchair in full gravity.

At about 45:45 of the stream, there's a quick video of what looks like camera footage of purple gas or liquid swirling around — really unworldly! Does anyone know what that video is of?


More information from my friend at SpaceX:

> This camera is on the second stage inside of the liquid oxygen tank. It’s on the top of the inside of the tank looking straight down, and what’s in the middle there between all lines pointing outward is the outlet of the tank that feeds the engine. I have no idea why the liquid oxygen looks kind of purple but this is a super cool shot because you can see the outlet, which has a device on it to make sure we don’t suck any gas through, and on the left side you can see one of the black tanks we fill with gas to keep the tanks pressurized to feed the engines!

They used to show tank footage more. IIRC they don't any more for secrecy reasons (government request?). Managing fuel in the tank is probably non-trivial.

Here’s a shot inside a Saturn I fuel tank with some nice narrative. https://youtu.be/fL-Oi9m2beA

If you dig around YouTube you’ll find a number of examples from throughout the space program.

Is this what you are talking about?[1] It looks like Stargate or some subliminal image slipped in.


That's it! Fuel tank maybe? It looks so bizarre.

EDIT: Looks like it's a peak into the LOX fuel tank.

Other question is why is the footage shown at all? Is there some limitation on the ability to switch cameras?

Footage from a fuel tank camera probably?

The oxidizer tank, specifically.

How incredible is it that FH is launching, and that they landed all three boosters, AND that it isn't even a news story anymore. Amazing.

I checked Google News in an incognito browser window, and this is the top item right now.

It's funny, if it went wrong more often it would be news but they make it look so easy.

They really do make it look easy, don't they?

These days, it seems like the hardest part of a SpaceX launch is maintaining the drone recovery ship video link.

Even though it looks easy, it's never gonna get old. Not for me, anyway. So great!

I really hope this will get old eventually, that means we have truly entered a new era for space launches and hopefully space exploration.

Well, it's news here, especially all 3 boosters. SuperHeavy should be news everywhere.

I'm having a hard time imagining what that's going to look like.

For those not lucky enough to explore this in person, Destin Sandlin from Smarter Every Day made a video [1] (from the test launch last year) that gives you a somewhat acoustical representation and a lot of good explanations.

I haven't seen a Falcon Heavy launch, but I've been lucky enough to see a 'normal' Falcon9 launch. There's 2 things that I know I didn't expect: The sound is just beyond anything. And I think the video above brings that across at least to some extend. The other part that surprised me when seeing a launch with my own eyes: The exhaust is bright. It gets lost quite a bit through cameras, so I was surprised how bright those flames are - even 30-45 seconds in, when the rocket is dozens of miles away.

[1] https://youtu.be/ImoQqNyRL8Y

I recently took my daughter to a Falcon 9 launch (the launch that included the moon lander that failed yesterday, actually). It was a night launch, and the exhaust was almost painfully bright.

Looks like no word yet on fairing recovery— according to the reddit thread, there were ships assigned to that duty, but it wasn't mentioned in the webcast and there's no updates I can see on it.

Elon just said, they recovered the fairings from the water undamaged and they are intending to reuse them for Starlink later this year. Source: https://twitter.com/elonmusk/status/1116514068393680896 and https://twitter.com/elonmusk/status/1116514534557016064

Jeez I had no idea the fairings had their own thrusters, steerable parachutes, and avionics.

Truly amazing stuff! SpaceX deserves all the credit. Three boosters landing is an amazing feat.

At 45:09 (T+ 00:25:12) for less than a second the video flips to...something...weird. Anyone know what that is?


Screenshot: https://imgur.com/GcDytsl

LOX tank cam - similar to this: https://www.youtube.com/watch?v=PPnCKK1isMI

I mean it's clearly a stargate.

Going for 4 for 4! Let’s not forget the successful payload orbit insertion. :-) We’ll see in ~15 minutes. Edit: Congrats SpaceX!

Nailed that too. What a day!

I always wonder why they don't deploy a [flying] drone next to the drone ship, to film and broadcast the landing from a safe distance. Probably just not worth the effort.

Good question, and you are probably correct, not worth the effort. There was one launch where they broadcast the drone ship landing from a nearby support ship (or helicopter, I don't remember exactly) which was cool to see but I haven't seem them do it since.


At this point, how far ahead is SpaceX from any other launch effort? 5 years? 10?

The only competition is BlueOrigin really. They are optimistically only 3-4 year behind. Then they should have a rocket comparable to Falcon Heavy.

The Russians are not really playing other then cheap mass production of old tech.

The European spent 4 years arguing and then came up with a something to compete with at the point when they started arguing. Now it will take another 4 years and then they are still far behind what SpaceX had 10 years ago. And that is totally without re-usability, in that they are another 5-10 years behind.

China is doing lots of things, but not as advanced or impressive and while they grind ahead consistently they are not close to SpaceX right now. At least they progress forward.

ULA is like Europe, targeting what SpaceX had 7 years ago and they will get there in 2-3 years. And then it will be far less impressive still in terms of re-usability.

India is just deploying cheap old tech.

That's basically it. SpaceX owns 50% of the US government launches, 50% of global commercial launches (large once at least). All the survives are 100% government depended, the commercial launch market is basically not close to profitable for anybody but SpaceX.

In terms of engine technology, its the same SpaceX and BlueOrigin are about to surpass the old glory of the US and the Russians and are moving into a new area.

You forgot about RocketLabs in Auckland. (I know they're no where near to SpaceX/BlueOrigin, but I know people who work there, so it kinda has a special place in my heart).

I love RocketLabs. But lets be real, that's a tiny launcher. It really not in the same market as SpaceX, BO, ESA, ULA and so on.

There are quite a few tiny launchers coming and RocketLabs is ahead of everybody. They did a great job, major probs.

But it like comparing electric scooter company compared to Tesla.

Far, but if Bezos were to incrementally sell off 15-20% of his total Amazon stock, he would still remain ridiculously wealthy, and could pour nearly unlimited amounts of funding into Blue Origin. At least enough to get New Glenn flying reliably in a reusable format and probably enough to fund a Super Heavy size successor to New Glenn.

By then, his competition will be the BFR.

Congrats to everyone at SpaceX for this epic achievement!

What are all the debris in the image [0] while the payload is coasting @ 192km above the earth?

[0] https://youtu.be/TXMGu2d8c8g?t=2740

Fluffy frozen oxygen, low mass. Bleeds from tank, all normal apparently

From where? Just hanging out above the earth as the atmosphere dissipates?

By only 202km it seems to have dissipated.


Thanks for the link! The frozen o2 is emitted from a drainage line on the tank.


I can picture the engineers of all the other commercial space companies in the world watching this and laughing, cheering and crying at the same time :)

This will be the closed to full reusability we ever came. The only thing that is not reused is the second stage. The boosters, core and the fairing are all removed, getting you up to 80% of the capital cost can be recovered.

Amazing and beautiful engineering. Imagine the satisfaction and the feeling you get knowing that you are part of a team that made all of that soar through the sky and back home safely. /applause


Great job SpaceX!!!

So proud of them for pushing human space exploration forward.

Luckily, I heard about it on the radio on the way home from work and got home a couple minutes before the launch, so I could watch it from my front yard.

Thank you Elon for advancing mankind in such a spectacular way! You are a good person.

Oops... forgot to walk outside to take a look.

Amazing! Such an inspiration!

3 for 3, Good job SpaceX!

This still looks like sci-fi to me.

That was fun to watch \(^O^)/

3 for 3! Beautiful!


My congratulations to Elon!

How on earth could they have not solved the drone ship landing video feed issue yet? Is it really that hard to keep a video camera working near a landing rocket? Even if the feed cuts out, can they not just record it locally and rebroadcast? It makes absolutely no sense.

> How on earth could they have not solved the drone ship landing video feed issue yet?

It's probably technically challenging and not a high priority. Why would this be something you want them to spend any significant resources on?

> Is it really that hard to keep a video camera working near a landing rocket?


> Even if the feed cuts out, can they not just record it locally and rebroadcast?

They literally do this all the time. Look at their YouTube channel, and you can see that they release the completed landings after the fact, even if the live broadcast cut out.

> It makes absolutely no sense.

I disagree. I don't think your expectations make any sense.

It makes absolute sense considering the live video feed is probably coming via a motorized 3-axis tracking Ku-band maritime VSAT system. If you look at aerial photos of the drone ships you can see the radome.

I suppose if they wanted to keep a feed up it would be possible to connect the cameras/network equipment on the ship to something with an ordinary 10Gbps 1310nm LX fiber SFP+ in it, attach 1 km of submarine rated fiber optic cable to a series of floats, and run a fiber optic cable to a small nearby ship with the satellite uplink mounted on it.

Great idea. Fouling the rotating props as they maintain GPS dead reckoning may be a risk they don't want to take.

Yeah, it'd have to be some kind of weird setup with the fiber coming off an extension arm sticking out from the side of the barge, and then at an angle into the water. Dynamic positioning vessels generally don't take kindly to having rope shaped things hanging around in the water near their thrusters.

If you have a ship nearby with the VSAT uplink, another way to do it would be a really low cost IP data point to point link in the 900 MHz band, even if the fresnel zone is deep into the water, it'll be good enough for 15-20 Mbps of traffic. Way more than the bitrate of the video coming off that camera.

Something like two Cambium PMP450i radios, two dual polarity 3 ft long yagi antennas, set up as a layer 2 ethernet bridge. The spread of that type of link's RPE in the 900 band means that as long as the VSAT uplink ship had some ability to stationkeep relative to the barge, you wouldn't even need motorized tracking antennas on both barge + uplink ship.

Or just use something like Iridium...

Or keep it as it is. Adds to the drama.

Iridium in its current form is 2400-3000 bps... The next generation network is not really commercially available yet. Can't squeeze much h265 video through that.

That's Iridium Go - pocket sized device. Certus devices (new constellation) does 360kbps, probably more if you signup for something.

> Is it really that hard to keep a video camera working near a landing rocket?


> Even if the feed cuts out, can they not just record it locally and rebroadcast?

Yes, but then it wouldn't be a live feed. Which is what they typically broadcast.


Great, I guess that settles it then.

>Yes, but then it wouldn't be a live feed. Which is what they typically broadcast.

Because streaming delays aren’t a thing?

They don't use streaming delays. They broadcast it live.

There's a huge difference between watching something LIVE and watching it on a delay. Sports are also broadcast live, and also wouldn't be the same on a delay.

Bigger issues to take care of...

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