39
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Ultimate fate of rocket propellant in space?
Presumably you are asking about engines that are used once a space vehicle has escaped the Earth's gravitational sphere of influence, or is close to that point. Rocket exhaust during launch becomes a ...
- 73.2k
24
votes
Collecting antimatter from Van Allen radiation belts
The total antimatter in the van Allen belts is estimated to be 160 nanograms. Annihilating that with matter would produce a whopping 8 kW-hr of energy. A quarter of a gallon of gasoline has that much ...
- 58.5k
23
votes
How does SpaceX plan to supply or recycle respiratory gasses?
How does SpaceX plan to supply or recycle respiratory gasses?
As with most questions about SpaceX, the answer to this question is essentially that SpaceX is a private company, and unless either ...
- 18k
21
votes
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Can a rocket refuel on Mars from water?
It absolutely could! First of all, water can be split in to hydrogen and oxygen, which can be enough to launch a rocket. Hydrogen requires a very low temperature, and the rocket engine doesn't have as ...
- 121k
17
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Would a sufficiently deep cavern on Mars provide habitable temperature and atmospheric pressure? Was Dick Tracy wrong?
Looks like it's not possible:
To get Earth-normal pressure we need 55km
https://astronomy.stackexchange.com/questions/14871/at-what-depth-on-mars-would-the-atmosphere-have-equal-pressure-of-that-on-...
- 11.5k
14
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Has trebuchet-based materials transport on the Moon been researched before?
It’s an interesting idea, but the problem will be accuracy. Depending on the conditions found on the ground, it might be difficult to produce uniform “ammunition” and an “engine” with a sufficiently ...
- 8,954
13
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Making propellants on Mars: Why not just LH2/LOX instead of methane?
Liquid Hydrogen is difficult to deal with. The temperature must be 33 K or lower. Liquid Oxygen requires 90K, and Liquid Methane is similar. The temperature requirements are far less as such. The ...
- 121k
13
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Ultimate fate of rocket propellant in space?
No need to theorize. Astronomers have studied this problem for centuries, as there are natural objects that emit conspicuous plumes of rocket exhaust. We call them comets. The exhaust forms two "...
- 2,181
12
votes
Most attractive resource on the Moon
First off almost all resource extraction in space is really only remotely close to cost effective if the resources themselves are used in space.
The general number thrown around is ~$10,000 per ...
- 2,391
11
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Which heavenly bodies have stuff to make rocket fuel?
To start off, literally everything can be used as rocket propellant. For a more practical approach though, water is a good resource for making hydrogen and oxygen.
In the Inner solar system we have ...
11
votes
Has trebuchet-based materials transport on the Moon been researched before?
I'm not sure if a thrower-catcher system is a good solution. Some points:
Getting a canon (or launcher of any sort) to fire accurately across four kilometers without precision machined shots or a ...
- 17.9k
10
votes
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Sabatier reaction oxygen to methane ratio for Mars ascent propellant
It's a 4:1 ratio by mass. One molecule of methane masses 16 daltons, whereas one of dioxygen ($O_2$) masses 32, so two molecules of oxygen massed four times as as much as one of methane.
- 19.3k
9
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Making propellants on Mars: Why not just LH2/LOX instead of methane?
As briefly mentioned in the previous answer, H2 is very tricky to deal with. The temperature is one thing, but what he didn't mention was its extremely low density. If I recall correctly the LH2 tanks ...
- 1,108
9
votes
Why didn't Apollo land on the Lunar poles?
The Apollo program contracted Bellcomm (a joint venture of AT&T Bell Labs and Western Electric) as technical advisors. It played a similar advisory role that the RAND Corporation often provided ...
- 47.7k
8
votes
What useful materials can be extracted from Venusian atmosphere?
Old topic, but for those just showing up:
There are two leading candidates for the "unknown UV absorber" in Venus's atmosphere, and probably the most likely answer is some degree of both. ...
- 253
8
votes
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What's the scientific evidence of water for return trip methalox on Mars?
There is an interesting podcast that I listen to - We Martians. Last Nov they had an episode that touches heavily on this. The episode is here: http://www.wemartians.com/home/015 and it goes into ...
- 766
7
votes
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How much land does a colony on Mars need to start off?
Of these, the only one that isn't well known is nitrogen. The nitrogen levels at Mars are somewhat unknown, but expected to be pretty low overall. Of course, nitrogen isn't required for a colony of ...
- 121k
7
votes
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What specific impulse can I expect from iron powder produced from lunar regolith?
Figure 5 on page 23 of this paper shows the Isp of tri-propellants including iron, where the curve goes out to 95% Fe and 5% H2. Just eyeballing it, the curves might converge at around 190 seconds. On ...
- 58.5k
7
votes
Why didn't Apollo land on the Lunar poles?
Assuming the counterfactual situation that NASA knew (or expected) that there would be ice in the polar craters, the reason NASA wouldn't do a polar Apollo landing is lighting.
In order for the crew ...
- 14.6k
7
votes
Can a rocket refuel on Mars from water?
Have a look at the wikipedia article for "In situ resource utilization". This is exactly what you're talking about, creating fuel on another planetary body.
https://en.wikipedia.org/wiki/...
- 2,544
6
votes
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Manufacturing solar cells on the Moon
Perovskites may prevent the need for such complex manufacturing facilities.
https://www.nasa.gov/feature/glenn/2019/building-solar-panels-in-space-might-be-as-easy-as-clicking-print
Perovskites are ...
- 804
6
votes
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What is the minimum amount of equipment you would need to make a reasonable amount of oxygen on the Moon with Molten Oxide Electrolysis?
You need to make 550 liters of oxygen in 8 hours. On average in the paper provided they made about 400 milliliters of oxygen per hour (throwing out the high and low outliers). That's 3.2 liters per ...
- 302
6
votes
Sabatier reaction oxygen to methane ratio for Mars ascent propellant
In practice, what you do is actually you start out with water to generate the $\mathrm{H_2}$, rather than just electrolysing the water that comes out of the Sabatier reaction. (Well, you'd probably do ...
- 3,585
5
votes
Are there proper ore bodies in Mars' crust?
It is not a given that all lunar meteorites are as scattered as the impactor of Barringer crater. Some meteorites strike as slowly as 3 to 4 km/s. And magnetic anomalies suggest rich metal deposits ...
- 15.6k
5
votes
Is Mars iron too oxidized to pick up with a magnet?
No, at least some of it will stick to a magnet. Here is an image of dust on the capture and filter magnets on the Opportunity rover on Mars.
- 58.5k
5
votes
Collecting antimatter from Van Allen radiation belts
The Enterprise uses Bussard-Collectors to harvest hydrogen from interstellar space.
While the Enterprise is science fiction, the Bussard-Collector - or more the Bussard ramjet1 - is a theoretical ...
- 781
5
votes
Accepted
How to produce oxygen out of Venusian atmosphere's carbon dioxide?
Some of your options are:
Electrolysis of the atmosphere (see e.g. how MOXIE will do it on Mars), for which you will need a source of electricity, a catalyst (e.g. zirconia), and which produces ...
- 76.5k
5
votes
Mining lunar thorium for building nuclear rockets on the Moon
Mining lunar thorium gains you nothing. Thorium is not fissile and cannot be used to fuel a nuclear rocket, power plant, or RTG.
Designs for "Thorium" nuclear power plants use thorium as a fertile ...
- 1,738
5
votes
Accepted
How much equipment will be required to mine 600 tons of water ice on Mars?
Unknown
This is very, very mission dependent. Where does it land? How long do they stay? What is the mission hoping to accomplish, beyond producing enough fuel to return?
Add in all the other unknowns ...
- 1,548
4
votes
Mining construction materials and other resources on Mars
You can make a kind of concrete from sulphur, although the idea of living in buildings made of a potentially poisonous material might not sound very attractive. There is also water which should ...
- 2,443
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