# Tag Info

38

Spooky This one is subjective. To some, just finding an abandoned spaceship would be spooky. I'll say there's probably not a lot that has to happen to evoke this feeling. Rusted Actually, unless your spaceship never had a breathable atmosphere or the atmosphere was vented before the spaceship was abandoned, rust is totally possible on the inside and ...

15

'Organics' usually refer to organic compounds. From Wikipedia: http://en.wikipedia.org/wiki/Organic_compound There is no single "official" definition of an organic compound. Some textbooks define an organic compound as one that contains one or more C-H bonds. Others include C-C bonds in the definition. Others state that if a molecule contains ...

14

Probably not any more likely than on Earth. Actually, Curiosity's (MSL) rover's wheels are made out of aluminum and they've been grinding through iron oxide rust that gives Martian regolith and the whole planet its color for quite a while now. And Spirit and Opportunity (MER) rovers also use several tools, among which even grinders, made out of aluminum. So ...

14

This took a fair bit of investigation! Arm Strength The Mars Science Laboratory Robotic Arm (RA) is 2.2m in length, is made of two arm sections (an upper arm and a forearm) and is controlled by 5 actuators. These consist of (among other things) a brushless DC motor and a planetary gearbox to step down the motor speed and increase torque. Two of these ...

12

Often, electrical systems prone to whisker growth are coated with a 2-3 millimeter layer of polymer (called a conformal coat); this not only prevents growth of whiskers, but also prevents any loose electrical contacts from creating short circuits. There are many benefits that are associated with doing this. Another likely cause of crystalline whisker growth ...

12

No, I don't think so. Combusted hydrazine smells like ammonia, because it is ammonia, plus nitrogen and hydrogen. Unburnt hydrazine also smells like ammonia, but has a sharp sting to it that, if you smell it, you should leave that building.

11

(Top edit: The Question asserts "Xenon and krypton are popular despite their heavy mass" and asks about exploring H or He ion propellants for improved Isp. This answer shows that lighter is not better for ion thrusters, because Isp is not the proper measure of a power-limited situation. Hence, although lighter atoms have been explored for other reasons, ...

11

1. Diamond. Its hardness is legendary. That it appears in liquid form on Uranus or Neptune hasn't been directly measured (no recent probes), but lab measurements in 2009 and 2010 of diamond's phase diagram still haven't been contested to claim that diamond can't be liquid there. On the contrary, in 2017 a process was demonstrated of converting diamond ...

10

What is meant by 'Organics' when discussing space exploration? It means compounds that contain carbon, except possibly for some simple carbon compounds such as CO2, carbonates and cyanides that historically have been deemed to be inorganic. In the 19th century, carbon-containing compounds were classified as organic or inorganic based upon 19th century ...

10

Two big ifs here. IF we achieved viable commercial fusion power (other than the sun) and IF He3 was an indispensable part of this process. But for the sake of argument, let's say He3 is the fusion fuel of the future. I'll quote John Schilling's comment from Rand Simberg's Transterrestrial Musings blog. Helium-3 mining on the moon simply does not pass ...

10

The Merlin engines are ignited with a mixture of triethylaluminium and triethylborane (TEA-TEB); according to Wikipedia: Triethylborane is strongly pyrophoric, igniting spontaneously in air, burning with an apple-green flame characteristic for boron compounds. Thus, it must be handled and stored in nitrogen or argon. Note that this effect should not be ...

10

450-455s Isp is typical of H2/O2; according to the Huzel and Huang data, a hydrogen-beryllium mix combusted with oxygen can hit ~540s. The numbers in that table are for moderate chamber pressure and expansion ratio; higher values are possible. According to Wikipedia: The highest specific impulse for a chemical propellant ever test-fired in a rocket ...

10

I'm going to start off with a warning: if you want to get started with model rocketry, it is about a thousand times safer and easier to start with off-the-shelf solid rockets. Don't even consider trying to build your own liquid fueled engine until you've learned a lot more. That said, reaching the RP-1 specification from commercial kerosene is probably ...

9

Chlorine is a relatively rare element, so the concentrations of it is not going to be high anywhere. It is also very reactive, so all of it is likely to only occur as a part of different chemical compounds. Chlorine is especially likely to react with sodium as it one of the most common elements, and also has a very low electronegativity. That makes sodium ...

9

As pointed out by @Thomas, this nice thesis Radiation from High Pressure Hydrogen-Oxygen Flames and its Use in Assessing Rocket Combustion Instability - Ph. D. Thesis, Fiala, T., 2015 discusses this phenomenon. The term $\color{blue}{\text{blue radiation}}$ is suggested as the best available. While there are several narrow spectral lines int the near UV (...

9

The theoretical limit is set by the specific energy of the reaction of combustion of the propellant. Knowing specific energy $e$ of given substance, we can put a cap on obtainable specific impulse $I_{sp}$ by assuming 100% of conversion of chemical energy to kinetic energy. $$I_{sp} = {v_e \over g_0}$$  E_{chem} = e m \geqslant E_k = {1 \over 2 }{ m ...

9

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.

8

The Moon would be a much better place most likely. As you said, 220 pounds of Helium-3 in a mass of many many tons of rock, makes it so that even a few tons of equipment to be dropped on the Moon would vastly reduce the price to return it home. Lifting 220 pounds from the Moon to return to Earth is relatively easy, all of the Apollo missions did it, and then ...

8

Absolutely, it's the same as heating up metals with a blowtorch. The colour of the flame tells you what is present. Wikipedia actually has a handy list giving an indication of the significant elements present: Orange-yellow (sodium) Yellow (iron) Blue-green (magnesium) Violet (calcium) And Red (atmospheric nitrogen and oxygen)

8

Non-hypergolic liquid fuels i.e.: LH2, LOX, Methane etc are all kept as pure as possible. One of the major advantages of these is that they burn clean. Any additions are potentially problematic: Complex combustion by-products, different density ratios leading to separation, and differential storage requirements etc seem to have outweighed any potential ...

7

Conformal coatings mostly, just like on Earth. A thin polymer layer impedes problematic whiskers principally by confining them to the inside of the coating. Theses links confirm that NASA has a large interest in the study of conformal coatings and likes to use them. The first one includes pictures of whiskers that formed under coatings towards the end. ...

7

That is the beauty of rocket engines, you can put almost whatever you want into them, and they still kinda work. (That said, I see that as beauty, engineers just scream in terror.) Joking aside, there is actually a little bit of truth in that, rocket propellant specifications are not that strict. For example, the original specifications for RP-1 just ...

7

If we have a pressure shock front travelling very fast through the material it is an explosion. The reaction inside the explosive is started by the sudden pressure rise, not by a temperature rise. But when the solid rocket fuel burns, we have a nearly constant pressure inside the rocket and no travelling shock front. The thermal conductivity of the fuel is ...

7

The spectrum you show from Titan was taken using the IRIS spectrometer aboard Voyager 1. Of course Voyager 2 had one as well. A huge amount of work went into developing and optimizing the design in order to develop a precise optical instrument that would survive both the high g-force and vibrations of launch, and the years in a space environment while ...

7

According to NASA's article "Rainbows on Titan": The density of liquid methane is only about half the density of water. This is something, say, a boat builder on Titan would need to take into account. Boats float when they're less dense than the liquid beneath them. A Titan-boat would need to be extra lightweight to float in a liquid methane sea. ....

7

Perchlorate contamination is a problem on Earth. Essentially, there is a series of water treatments and bioremediation, the process of using biological systems to fix the problem. Here is a detailed summary of one effective approach. The short answer is this: Engineers know how to do this on Earth, and the Martian solution is likely to be an adaptation of ...

7

Xenon can be found elsewhere. Wikipedia's Xenon; occurrence and production mentions a relatively high abundance of xenon on Jupiter, which is actually unexplained. But xenon is overall among the rarest elements everywhere, because of its high atomic number (requiring special processes to synthesize) and it's low tendency to form compounds. Within the Solar ...

7

From Mars Fact Sheet: hydrogen (H), carbon (C), nitrogen (N), oxygen (O), argon (Ar), neon (Ne), krypton (Kr), xenon (Xe). From Inorganic analysis of martian surface samples at the viking landing sites: (DOI: 10.1126/science.194.4271.1283) silicon (Si), iron (Fe), magnesium (Mg), aluminum (Al), sulfur (S), calcium (Ca), titanium (Ti), strontium (Sr),...

6

I believe electrolyzing would take at least 286,000 joules per mole of water. See this Wikipedia article. A mole of water would give ~16 grams of oxygen and ~2 grams of hydrogen. So to make a million grams of propellent we'd need at least (1,000,000/18)*286,000 joules. That's about ~15,888,888,889 joules for a tonne of propellent. According to this NASA ...

6

As best as I can understand from these papers, it would seem that the precise levels are not known, but that noticeable weathering on Venus implies significant(?) levels of oxidation on the surface. The papers primarily address the oxidation of Fe (iron) mineral on the surface. Most of the material in the papers is derived from modeling of the surface and ...

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