
In 1957, Two Tiny Pellets Were the First Objects to Escape Earth’s Gravity - curtis
http://www.airspacemag.com/daily-planet/1957-two-tiny-pellets-were-first-man-made-objects-escape-earths-gravity-180954622/
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pinewurst
Actually a manhole cover might have preceded the pellets, and Sputnik too, on
August 27.

[https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_...](https://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap)

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mrestko
Sputnik orbited, it didn't reach escape velocity to leave the influence of
Earth's gravity.

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madaxe_again
Here's Zwicky's own write-up of the event.
[http://calteches.library.caltech.edu/1801/1/zwicky.pdf](http://calteches.library.caltech.edu/1801/1/zwicky.pdf)

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PMan74
> “I am certain they escaped,” Zwicky rejoiced

How was he certain? Is science not all about observation?

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madaxe_again
There was observation - see his paper -
[http://calteches.library.caltech.edu/1801/1/zwicky.pdf](http://calteches.library.caltech.edu/1801/1/zwicky.pdf)
\- they saw the particles streak up out of the atmosphere, and measured their
speeds.

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IgorPartola
I was thinking about something similar last night: what is the cheapest way to
get an object to the moon? Basically, let's say that any object of any size
counts, and any location on the moon counts. What would be the easiest and
cheapest way to assemble an apparatus that could deliver it? What if we add a
restriction that we want to somehow prove that it made it to the moon, such as
being able to observe it on its way, or have it transmit its telemetry as it
goes? Would a GoPro with a Wi-Fi cantenna work? :)

~~~
paulmd
That's a complex and abstract question. Are we counting as going from Earth's
surface or orbit, and if it's an orbit which one? Are we counting the cost of
launch infrastructure in this? Does the object need to survive impact? Is
there a time restriction on how long this can take?

Overall it's a question of lifting mass. Rockets are reaction engines, you
need to expel mass in order to move. However, you also have to lift that mass
in the first place, which means you need more fuel to lift your extra fuel.
It's a massive feedback loop and increasing the payload (or delta-v
requirements) results in exponential growth of the total mission load (and
thus cost). Staging is very important - if you drop the early heavy launch
stages the later stages need to move a much smaller mass, hence the
traditional distinction between rocket and spacecraft. Big rocket gets you
near orbit, medium rocket kicks you into orbit, small rockets on the
spacecraft kick you onto a translunar trajectory, into lunar orbit, then send
you back.

You can really divide the mission into two phases. The first phase is reaching
orbit, and it's currently where the vast majority of the fuel is expended.
Chemical rockets have a fairly low infrastructure cost, but as a result of the
fuel equation they have absolutely insane operating cost. Spaceplanes can be
more efficient over their entire lifespan because you're not throwing away the
whole airframe with every launch, but they tend to have inefficient staging
that becomes exponentially worse as you go farther out (you don't want to have
to lift aircraft engines into space, or move your orbital injection airframe
into lunar orbit, etc). Everyone likes the concept of Single Stage To Orbit
but there's a reason the Shuttle drops its boosters and fuel tank.

If you can find another way to get your craft to space you greatly reduce the
overall cost of your mission. Space elevators are the fantasy but require
exotic materials like carbon or diamond nanothread. The launch loop is an
interesting design that can be attained with present-day materials. Another
option would be to manufacture your craft in space. If you pull an asteroid
into orbit you have an _unfathomably_ abundant source of materials. An average
asteroid has about 10x the quantity of precious metals ever mined in human
history as well as craptops of iron, nickel, lead, etc. And it would all be in
easy reach, outside the worst of Earth's gravity well. The husk can be used as
an Aldrin cycler. These all have fairly large infrastructure costs, ranging
from billions to trillions, but would offer very low-cost payloads once built
out. For example a launch loop would cost about $30 billion and reduce launch
costs to $3/kg. In comparison SpaceX spent about $400 million to develop the
Falcon rocket and costs $1k/kg for payload, and this is a comparative bargain
for chemical rockets. The first hamburger is very expensive with alternative
launch methods, but in the long term the price is much more reasonable.

The other half is the lunar phase of the mission. You need to get the object
out of Earth's gravity and into the Moon's. In theory as long as you leave the
Earth's sphere of influence and are inside the Moon's it will eventually be
pulled in and impact the moon, but this could take a really long time and you
are giving up a lot of control over how the payload arrives. If you want a
delicate payload to arrive safely you need to allocate weight for motors,
fuel, and a guidance platform. Take a look at the mission profiles considered
for the Apollo missions - Lunar Orbit Rendezvous (you inject into lunar orbit,
then later begin a descent) or Direct Lunar Ascent (you aim straight at the
lunar surface and brake yourself in one go). Direct Ascent is faster but takes
more fuel, so we went with the LOR profile.

Other missions can have very different needs. For example, for long-term long-
distance unmanned missions, electrical/ion rockets become very compelling.
They have superior thrust-to-weight but very low thrust levels - so you can
accelerate or decelerate a lot (delta-v) but only fairly slowly. For
travelling interplanetary/interstellar distances at human-relevant timescales
you need a stronger kick. The best design so far is nuclear pulse propulsion
(see: "Project Orion"), which operates by chucking nukes out the back and
riding the shockwave. It's a childish idea (I came up with it independently
myself as a child) but it _works_ \- it gets you large payloads (it actually
works better as it scales up) moving at significant fractions of the speed of
light (0.10-0.33 _c_ ). It's an environmental disaster, of course, you
couldn't fire the engine anywhere near a planet.

Intelligent use of orbital mechanics can further decrease your needs. For
example you can "slingshot" through a gravity well, which lets you steal an
infinitesimal amount of the planet's velocity. If you burn your engines as you
descend, you keep your velocity but also don't have to lift the mass back up
again. However, the planets rarely align that this is a useful maneuver. This
is actually a general rule - getting there quickly takes a lot of fuel and if
you are willing to wait for orbital mechanics to work in your favor you can
greatly reduce fuel requirements (see: Hohmann Transfer). The extreme is the
Aldrin Cycler - a spacecraft placed on a periodic orbit between Earth and Mars
with a duration of several years. Once injected into its orbit would require
no fuel except for small corrections.

Specific response to your question - the cheapest one-off is a small, staged
rocket that pushes itself just over the boundary into the Moon's sphere of
influence and then gradually arrives however many years later. If you specify
that it needs to be verifiable, you attach a proximity-fuzed grenade that
scatters a cloud of retroreflective material onto the surface, which you can
identify using a laser. That frees you from the need for guidance or
deceleration to prevent a catastrophic impact. You do need to give it enough
of a trajectory that assures it arrives on the light side of the moon,
however. Time limits are handled by increasing fuel load.

~~~
IgorPartola
Wow, thanks for the awesome response. To narrow it down a bit, I was wondering
about the feasibility of launch this type of thing out of basically "my
backyard". So something like a launch loop would be out of the question, and
so would mining asteroids. Basically, can someone outside of NASA or SpaceX
land an object on the moon that takes, say less than 5-10 years to arrive.
Does it take $10k, $100k, $1m, $100m, etc.? Just idle wondering.

The thing I was thinking about at the same time was my college professor's
electromagnets. They would run on the order of 9 Tesla and he claimed could
launch a bolt at greater than escape velocity straight up. Those cost I think
on the order of $10k plus his expertise (he manufactured them himself).

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scelerat
What does that even mean, "escape the influence of Earth's gravity"? Even the
sun is under the influence of Earth's gravity.

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dekhn
No, there were previous objects that escaped earth's gravity (for example,
there are rocks from Mars on Earth, and the opposite is also likely).

~~~
dalke
HN has an edited title. The original one at the Smithsonian qualifies it as
"First Man-made Objects".

