andrewas

Its going to take a lot of power. The probe is going to have to melt its way through 10 to 30 kilometers of ice at very low temperatures, unspooling a cable as it goes. The 30Km of cable alone mean the probe is going to have to be huge, never mind the multiple exploration craft that should be carried to maximize the science return. An RTG putting out a kilowatt or two isn't going to cut it. Its going to take a fission reactor or other equally high density power source.

And yet, humans manage to produce objects of equal complexity. Producing identical clones would be no harder, its just that evolution favours sexual reproduction with each individual being slightly different.

Go here: https://nuage.nibb.fr/index.php/s/ohAfTU2W9unu8eI/download Your browser will complain about an invalid SSL certificate. In most browser, you can usually add an exception for that site which will let you see the pics.

Or its a typo for 'acoustic', which fits with a torpedo acquiring and hitting the ship that launched it - with WW2 technology, the best you can do is home on the loudest sound in a given arc.

No. Well, slightly, since photons lose energy as they climb out of the gravity well, but its negligible. But the important thing for solar panels and illumination is how much energy is delivered to a given area. Double your distance from the star and you get 1 quarter of the energy density.

In reality, Earth's gravity is non spherical, and this causes the orbit to precess. If you choose an appropriate inclination and altitude, the orbit can be made to precess once a year, which will keep your periapsis pointed at the star. This is usually done with earth imaging satellites, so that they get the same angle of illumination with each pass, which makes it easier to assemble mosaics from multiple passes to image a wide area.

1) Its not the relative speed of the wave that's important, its the apparent wavelength. Move towards a wave source and the wavelength you measure is reduced. 2) Nothing is moving faster than c in any reference frame. From your frame, the distance between the two waves is reducing at 2c, but that distance doesn't correspond to anything phyiscal, its just a measurement between two points. If we substitute the light beams for two relativistic spacecraft, then we can talk about the frame of reference of those spacecraft. Both spacecraft will measure you coming towards them at near-c and the other spacecraft approaching at a slightly higher velocity.

The MAV is landed by the previous mission so that there's a human pilot involved, not because it needs all that time to make fuel. Also, hydrogen boiloff means they probably designed it to make methane more quickly than that. The MAV can replace LOX easily but has no source of additional hydrogen. Also, Watney brings solar cells with him and may have been able to amp up the fuel plant a bit.

I thought you were still talking about the descent stage of the MAV?

He uses the fuel plant from the MAV to produce C02, the Hydrazine and catalyst come from the MDV. Theres no suggestion of any part of the MAV using hydrazine. Unless - the MAV brings hydrogen with it to produce fuel, but hydrogen is worse for boiloff than LOX is. Its possible that there is a descent stage, and excess hydrazine is decomposed to produce the hydrogen the fuel plant needs. However, Mars Direct, which much of the mission in The Martian was based on, claims that hydrogen boiloff can be reduced to 1% per month using insulation and gelling the hydrogen with methane.

Methane's triple point is over 11 kilopascals, pluto's atmosphere is closer to 0.3 pascals.

This was Energia-M, a much smaller rocket intended to re-use Energia components and preserve the infrastructure. This was built at the end of the soviet era, I would guess the artwork with the NASA and ESA logos was produced after the fall, in the hope of getting some foreign payloads to fly, since the russians had nothing to justify a rocket that large.

The MDV was hydrazine powered, I can't find any mention of a Hydrazine engine on the MAV. It would make sense to have both stages use Metholox engines, that way you can re-use the descent stage as the first stage on the way up. There shouldn't be any excess tankage on either stage, but methane and LOX are fairly easy to store, so perhaps Watney used tanks from the Rover or MAV life support systems.

If I'm doing the math right, he's putting out 8.34Kw of heat on average. (Assuming he produces 47L of water per Sol, which is the rate he mentions after recovering from the explosion) Thats a lot, particularly since the peak output will be much higher, but its not unmanageable, particularly since he can halt production if the temperature gets out of hand, and sleep in the rover if the hab doesn't cool in time.

Homeopathy is about finding poisons that cause the same symptoms as the disease, so it can be applied to fighting a virus as well as anything else. Have a fever? Take a poison that causes fevers and repeatedly dilute it till there are no molecules of it left in the water, use that water to make sugar pills. You have a homeopathic fever cure. And if you do it on an industrial scale, you make millions.

They make more. The casings are just steel, manufacturing new segments would not be hugely expensive compared to the rest of the rocket. If they somehow fly enough SLS to use up all the existing boosters, its not a big problem.

No. This is something that would be built when there are permanent colonies, its useless for exploration missions.

All 2-body orbits are conic sections - shapes that can be generated by slicing through a cone. Patched Conics is when you patch together multiple conic sections around different bodies to plan an entire mission. In reality, its a useful approximation, you can quickly put together a mission and get a rough idea of whats possible without spending too much time computing it. In KSP, its exact because KSP doesn't use N-body physics.

AKA Fool's Gold - its a salt of iron and sulphur, and doesn't look much like gold but people have made the mistake in the past.

That would risk triggering a Kessler cascade, after which nobody has anything in LEO.

Pyrite doesn't melt, it decomposes. If he melted it, it was gold or an alloy that looks enough like gold to fool him. Brass maybe.

They might be saving that for a lower orbit, where they can get more detail of the bright spots than they can from the 4400Km survey orbit.

Not a glass dome, something more flexible so it can be supported by the atmosphere under it. But even if you dome huge craters that way, you're still creating fragile habitats, whereas a properly terraformed Mars needs its atmosphere topped up every few millenia at most.

You're not including the mass of the empty tanks and the engines on each stage.

Any orbit obtained in a single push will intersect the ISS's orbit, but the ISS might not be there when the astronaut hits the intersection. If the push is normal or antinormal, then the astronaut will hit ISS in half an orbit. An EVA suit should be good for the 45 minutes this will take, so the character should be able to re-board the station. Prograde or retrograde will change the astronauts orbital period, so if he pushes backwards he will drop below and overtake the ISS, drawing further ahead of it with every orbit. There may be a solution where the astronaut hits ISS as hit overtakes it, but the initial push would have to be tiny for that to happen. Not sure on radial thrust, but I think the period does change so the astronaut isn't getting home any time soon. Note that in any real situation, the push off won't be perfectly aligned with one of these axis. So while you can get back to the ISS in 45 minutes by pushing off in the normal direction, the inevitable prograde or retrograde component will be enough to cause you to miss the ISS.