# Tag Info

3

In light of a very recent news item I thought I'd turn my comments into answer so the information isn't lost should comments be deleted. Having visited a mineral processing plant that used bacteria to treat ground up minerals from a mine, two things struck me about plants that rely on bacteria to do useful work. The first is the bacteria usually need a ...

2

How much fuel would it take? And how large should be a booster / rocket ? That depends on the engine and propellant. Tsiolovksy rocket equation is $$\Delta V = \ln\frac{m_i}{m_f}I_{sp}g$$ where $\Delta V$ is change in velocity (in this case, 11000 $\frac{m}{s}$) $m_i$ is the initial mass before the burn (payload plus propellant plus dry mass for the ...

4

There are two figures which matter here: one is the energy that ends up in the thing you are accelerating. This is just given by $$\frac{m_P \Delta v^2}{2}$$ Where $m_P$ is the mass of the thing, and $\Delta v$ is the change in velocity (I am tacitly assuming that this kinetic energy is relative to someone for whom the object is initially at rest. The ...

2

Kinetic energy is $\frac {1}{2}mV^2$ so you're looking at $55$ GigaJoules of energy. That's enough to power ~86 U.S. homes for a year according to this U.S. EIA FAQ

3

Such a technique, while possible, is very impractical. This is in part because, in leo and even at the karman line, the atmosphere is so extremely rarified that it no longer acts as a fluid and instead is simplified to the interactions of individual molecules. Gas molecules collide 100,000,000,000 each second and travel 500 times the length of the atoms ...

3

As the narrator says almost immediately afterward, they're looking at using water as shielding, not gaseous hydrogen; you need to bring water along anyway, might as well store it around the crew spaces to serve as radiation shielding as well. Some groups are also investigating hydrogen-rich polymers as a possible barrier to GCRs.

2

Yes At least according to this recent video by Scott Manley. He points out that purely mechanical compression suits for high altitude flights exist and work. For example the suit Felix Baumgartner wore during his Red Bull Stratos skydiving jump from 40km altitude. You need a certain oxygen pressure in your lungs to avoid boiling of water and to be able to ...

-1

Radiation would be a problem. Nasa space suits are radiation shielded, as well as pressurized, contain a drinking water tube as well as a way to get rid of that water at the other end. Space is full of hard radiation. Cosmic rays are high speed particles that can cause serious damage to your cells, resulting in cancer or other issues. Astronauts who have ...

11

Another engineering aspect is controllability. Most electrical/mechanical/chemical life support systems can be throttled to anywhere between 0% and 100% of production capacity within minutes, if not seconds. In particular you can shut the system down for repairs and also carry a fully inert system as a cold spare. And since the atmosphere inside a spacecraft ...

1

Probably on the order of a V-2 strike with perhaps a bit more accuracy. However, passenger Starships will most likely have several layers of security, one of which will most likely seen early on in iterations towards that goal: a separable passenger compartment. In the event of any emergency, the passenger compartment is pulled away (perhaps with Super ...

8

Environmental Control, and Life Support Systems need to be tailored to their application. There are many tradeoffs such as how much they weigh, how complex they are, how reliable they are and how efficient they are. As a general rule the longer the duration of the mission, the greater the gains from life support closure. So missions of a few days can get by ...

19

Why this wouldn't work? It works for the Earth; the reason why it is not implemented in space is purely in the engineering limitations. Cyanobacteria live in water, humans live in air. Gravity is good at separating water from air, leaving a surface for the gas exchange. Microgravity is very good at mixing everything, so we should think about another ...

4

First of all, the idea as proposed in the movie is pretty crazy. What they would more likely use is Kapton tape, which is a kind of space rated duct tape. It's yellow-brown, actually could hold an atmosphere reasonably well for a short period of time, wouldn't outgas, etc. See the two compared below. There are two obvious problems for the show in this ...

1

This makes sense for the most part, only that if this were a regular starship, this docking port would lead straight into the header tank. does this mean that the new lunar starship will forego the header tanks and just use RCS to ullage the tanks, or is there another more versatile method? I understand that it will be making use of many other landing motors ...

2

it would have to be pressurized. EVA suits require a cooling suit to regulate temperature, because the outside of the spacesuit itself can become extremely hot or cold and would cause burns if touched directly with skin/thin fabric of only a flightsuit. i would say unpressurized, it would be ineffective and you would die. just because one COULD last in a ...

6

If will work fine, in the extreme short term. Like, 2 minutes tops. With no protection from the vacuum, you have to void the air from your lungs.. Unconciousness in 15 seconds due to very rapid oxygen loss through the lungs. (your lungs will also take all sorts of interesting damage, but you will be dead already) With a pressurized seal, such as this ...

3

Both things you mention have been worked on, conceptually or actually. The paper I'm familiar with on sling launchers is one by Geoffrey Landis, but he states he is expanding on earlier work. His paper is on ResearchGate - Journal of the British Interplanetary Society, Vol. 58, No. 9/10, pp. 294-297 (2005). Analysis of a Lunar Sling Launcher. That version is ...

0

This would have a very low specific impulse, closer to firing projectiles from a machine gun than to ejecting gas at several km/s. It would need an awful lot of bullets to build up speed. Another way to say this is that the mass of the fuel would be an impractically high fraction of the craft's total mass.

8

Completely impossible. The problem is you can't breathe. The average person can only breathe against about 5,000 pascals of pressure. On the summit of Everest you have 5,700 pascals of oxygen. Beyond that you have the problem that duct tape doesn't stretch. How are you going to inhale at all? If you want to be able to breathe you need a hard helmet and ...

32

If the suit would be useful, it has to be inflated. Which is definitively not how it looks like in images. If you could manage duct tape to hold the inner pressure for a moment without rupturing and/or leaking immediately, it would clearly help, but in the same moment, the "suit" would turn so stiff from pressure that it would be impossible to ...

6

Interesting question. First of all, they possibly wouldn't experience extreme temperatures over the period of a part of a minute if they do not touch anything. The real problem is indeed the possible gaps in the suit, but one should not expect any bleeding. Withdrawing air pressure is not enough to make normal skin bleed. I think the main problem would be ...

5

Starship cannot hit the ground at 11 km/s. Those speeds are only attainable in a vacuum. As the ship reenters, it slows down due to the atmosphere, and it continues to slow down pretty much the entire way to the ground. A falling object will have a terminal velocity of about 100-200km/h depending on its shape. Starships empty mass is a lot less than a Boeing ...

1

They could strike one small ground target of opportunity, or do something hugely visible like destroy the ISS. A fully fueled Starship in LEO could theoretically burn to deorbit anytime in the next orbit or two and come down mostly empty on any point beneath those next few orbits - but that would severely limit the sort of critical targets they could hit to ...

21

They do! Many propellant tank, especially those required to work in zero-g environments, do use just such a bladder-inside-a-tank for the fuel. Typically monopropellants for thrusters. It completely removes the requirement for Ullage of the propellants, but adds complexity, cost, mass and failure modes. Additionally, flexible bags are a bit hard to make at ...

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