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4

Rockets thrust works because of conservation of momentum, which is a fundamental law of our universe. When hot gasses are pushed out of the rocket, they exchange momentum with the rocket in the opposite direction. As a result, rockets don't need to "push" against anything on the business end. It's often misunderstood as a wing or helicopter rotors "pushing" ...


25

Rocket engines (unlike jet engines and internal combustion engines) are designed to work without drawing air from outside. A moon lander carries 2 tanks: one filled with propellant, the other one filled with an oxidiser. The rocket engine combines these two and ignites the mixture. The exhaust product provides thrust both in an atmosphere and in a vacuum. ...


14

Spacecrafts, including Apollo Lunar Module (LM) lander, use propulsion for retroburns, thus decreasing their velocity as they descend. This method works in the vacuum of space as well as in the atmosphere.


21

The US National Institute of Standards and Technology (NIST) is pretty useful for that. They offer a free tool that allows you to calculate a lot of useful properties of multiple interesting compounds including e.g. oxygen, nitrogen, helium, hydrogen, methane and propane: https://webbook.nist.gov/chemistry/fluid/ E.g. we can plot the density of Oxygen at 0....


5

Moon Loping is a form of legged lunar locomotion performed by humans on the natural Earth satellite (the Moon) where the human propels itself through a space above the lunar surface along a ballistic trajectory with relatively long duration of the floating phase. Lunar gaits page gives the following description: Most of the astronauts on the later ...


1

Since the bulk of regolith has a density of 1.5 g/cm3, and "talc, broken" has a density of 1.746 g/cm³ I wonder if comparing the two has validity. Density is not the only factor in how a substance feels to walk on. What matters is how the material behaves when a weight is placed on it. is it compressible? can the grains slide over each other to move out ...


8

According to Apollo 11 Lunar Surface Journal, Armstrong made his first description of the regolith as soon as he stepped out from the ladder and pronounced his famous "giant leap" phrase: 109:23:38 Armstrong: I'm at the foot of the ladder. The LM footpads are only depressed in the surface about 1 or 2 inches, although the surface appears to be very, very ...


2

Partial answer so far... For the trajectories in your drawing the objects will miss the Moon. They pass much closer to Earth, so their orbital motion will be substantially faster than the Moon's so they will pass through the interception points days before the Moon does and definitely miss it. However if those are elliptical orbits with the same semi-...


1

The question here is not so much about pressure fed engines as about thrust. If you need to land 240 tonnes of space craft on the moon you need to overcome at least the force of lunar gravity on that mass with engine thrust or it stops being a landing. So there is a fixed lower amount of thrust needed to land a given craft on a given body and it scales with ...


2

Some key points to consider: The longer you are applying thrust against gravity, the more fuel you require. An orbit is an orbit; low-Earth orbits, the Moon's path around Earth (or more correctly, the Earth-Moon barycenter), and even Earth-Moon or Moon-Earth transfers are all orbits, and arguably all Earth orbits. Earth-Moon transfer is a special case ...


1

I had to set up a whole page to experiment with Horizons, and after weeks of testing I ended with this url, which you can see here exploded for better readability: https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1 COMMAND='-85' <---- Target: LRO orbiter CENTER='coord@301' <---- Observer: Specify coordinates of point on surface with ...


1

There isn't a problem with sunlight supply at the south pole. It's actually the opposite situation. One of the biggest attractions to the lunar south pole (after water) is the fact that there are areas there that are in almost constant sunlight. From the rim of Shackleton crater, the sun skims the horizon to a complete 360˚ as the lunar day progresses. It's ...


2

The answer is no, you cannot have a static satellite. It would require high delta-V continually thrusting the mirror upwards. Solar sails do not have high delta-V. But that is okay - if all you want is polar moonbase illumination, that problem is already solved: Solution 1 - Have a network of satellites with mirrors, and use them in turn as they pass near ...


4

The lunar environment is actually quite a bit more harsh than Mars. Between dust, long day/night cycles, more extreme temperature cycles, and other things, it really isn't trivial to build for the Moon. In addition, there are a large number of price points for different missions. VIPER is at the lower point, while Curiosity is at the higher point. By using ...


0

I'll post this interim answer for now. Hopefully a primary source can be found and at that time someone can post a thorough answer. The following paragraph in Space.com's NASA Will Launch a Lunar VIPER to Hunt Moon Water in 2022 seems to summarize how VIPER will operate. However I am not certain that this is correct. This 2006 Lunar Polar Volatiles Explorer ...


1

If you think about it, the Earth is at the same distance from the Moon that the Moon from the Earth (of course), so the Earth at the lunar surface should be 4 times bigger in appearence.


0

About Apollo as a baseline: The Apollo program and its "before the end of the decade" timeframe was driven by informed speculation about what the US could achieve in order to overtake or at least close the gap on the (then) Soviet Union in the "space race". About timeframes: NASA's own plan for a (crewed) return to the Moon aimed for 2028; the 2024 ...


1

Concern was not that the lunar dust will rise and cover the solar panels or instruments. The concern was as pointed out in the comments is that the dust particles rising up and hitting the lower bay of the lander and damaging or punching a hole. The simulation was done to study plume interaction with soil, the four plume cones when they interact with ground ...


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