# Tag Info

43

Disclaimer: I worked as an aerospace engineer for 15 years for the USAF. Our organization managed the 53 Federal Stock Group (1) (among others), which includes Bolts, Screws, etc. By this I mean to suggest I have some (dusty) knowledge of this subject. While the quality control is very much a part of the process, as suggested, that alone is not the only ...

32

The Urine Processor in the Regenerative Environmental Control and Life Support System uses hexavalent chromium as a pretreatment solution for the urine.

28

I'll mostly focus on prevention of accidental cold-welding in vacuum of space, but for reference, one of the possible causes for the Galileo high-gain antenna deployment anomaly that was considered (1) was also "Retention of the ribs at the mid-point restraint due to friction, cold welding, or adhesion". Preventing accidental cold-welding: ...

27

The spectral data came from the surface of the material only a few atoms thick which is exposed to hard vacuum. The solar wind has ions of many materials. It is mostly hydrogen, which as an ion is just a proton. Or hydrogen atoms. Either one can react. The solar wind is not very energetic but it contains small amounts of other elements like oxygen and ...

26

Composite materials work well in temperatures commonly encountered in all weathers on Earth, but rocket elements swing between temperatures of liquid hydrogen (where polymer components become very brittle) and thousands of degrees of air resistance and combustion radiation (where composites simply burn), and brutal temperature shifts once in space. Never ...

25

note: protests in comments have led me to add the following sentence. Arsenic is a toxic metal and arsenic is used on the ISS, but the arsenic used on the ISS as discussed below is not a toxic metal per se, instead it's a nasty, extremely toxic semiconductor. GaAs is soluble in HCl which means if you eat it you are eating soluble arsenic. So don't eat it. ...

24

There's a Spinoffs from the Space Shuttle Program page hosted on the NASA Marshall Space Flight Center portal. According to it: Jewelry Design — Jewelers no longer have to worry about inhaling dangerous asbestos fibers from the blocks they use as soldering bases. Space Shuttle heat shield tiles offer jewelers a safer soldering base with temperature ...

23

Supplemental to the other answers; you are correct that the net force on the tether would be minimal, since the rotation of the counterweight would counteract the force of gravity. But, the individual components of this net force aren't being distributed evenly. Consider, say, the first kilometer of tether from the ground. This is being pulled down by ...

22

A 3D printer on station isn't likely to lead to direct cost savings; the range of items it can replace are limited, and it has to be supplied with feedstock mass in any case; it won't allow for significantly fewer supply launches. The primary benefit is that it can allow for the repair of a system the astronauts would otherwise have to do without until the ...

21

The bearings on the CMG (Control Moment Gyro) rotors use beryllium, which is pretty toxic when you machine it.

20

There's a pretty good Wikipedia page about it, which lists a couple of options: Water makes for fairly good radiation shielding (also discussed with land based radiation here), but is relatively heavy and is consumed during flight. Liquid hydrogen is also good, and is used as fuel, so it will already be on board. However, this too is consumed during flight....

19

(with considerable help from "Why we'll probably never build a space elevator") You have laid out a good foundation, for the first, and largest challenge, namely the material for the cable itself. Carbon Nanbotubes are the best substance we know of to build a Space Elevator. In their purest form, they have a tensile strength of over 100 GPa. The exact ...

19

Kirchhoff's law is only valid for objects in radiative equilibrium. The emissivity and absorptivity of a material are the same for a given wavelength, but can vary dramatically for different wavelengths. The radiators on a spacecraft are not in radiative equilibrium, since they lose heat to radiation. They emit heat in the longwave infrared spectrum, but ...

19

The 3-D printer on the ISS is more for testing purposes than anything. The idea is that for really long duration missions, a 3-D printer will allow them to make something in case something breaks, or they realize they need something that didn't come initially with the ship. So far I can only find a few things that have been made, including a ratchet, several ...

19

First of all, can the color even be seen? James Webb has a spectrum of 600 nm at the lowest end, which means it can just barely see the color red. In addition, it could potentially be seen in other wavelengths that aren't visible. The spatial resolution is around 70 milli-arc seconds. That means that the Roadster, being about 4m in size (roughly) in it's ...

19

There are four(ish) primary contributors to "space weathering" of any material (natural or synthetic) in space: Micrometeoroid and debris environment: This is the result of small stuff hitting the material in question. At possible collision speeds of up to 14 km/s (for debris, much higher for micrometeoroids) everything becomes a bullet. The ...

18

Light interacts with fresh metal surfaces in only the first few atomic layers. What makes metals "metals" is the very high electron density, and we can think of that electron "plasma" as having such a high plasma frequency that the light barely penetrates a tiny fraction of a wavelength before being re-radiated backwards by all those ...

17

Edit: added more information on why composites aren't common yet. Most of a rocket's structure consists of LOX and fuel tanks. Historically, carbon composites were viewed as too flammable to be used safely for tanks. Carbon composites failed standard tests used by e.g. NASA to determine flammability. In 2001, a study was done to re-examine this decision. To ...

16

Mars has extensive iron oxide ore. Much of it on the surface. Not readily extracted, but extractable with the correct smelting process. It has silicates, as well; this allows for glass. It has carbon dioxide; with a solar panel farm, and a cracking solution, that's oxygen for the taking. And that's just materials available readily at surface. Mars will ...

16

Parts for use in aircraft have to be certified. This means they need to be produced from standardized materials, using a standardized and traceable process. The part must be checked thoroughly during production, and the entire history of the part must be recorded. The tests and paperwork often account for most of the cost of the part. \$100 bolts are not ... 15 ESA-built Cupola uses "Fused silica and borosilicate glass" for all its windows including biggest 80 cm one (reference is http://www.esa.int/Our_Activities/Human_Spaceflight/International_Space_Station/Cupola) In http://www.esa.int/esapub/bulletin/bulletin137/bul137h_deloo.pdf on page 7 (labelled 66) there is text about previous 50 cm window on ISS The ... 15 While not a matter of materials science, my A&P gave me his explanation of the subject when my plane was in for annual: Mechanic: These two screws are identical. This one comes from Home Depot and costs 25 cents. This one is comes from an aviation supplier and is certified for use in your plane; it costs \$2.00 per screw. If I use the Home Depot one ...

15

The short answer is no. Hulls of airplanes are much much thinner than those of ships, spacecraft hulls are even thinner. Think somewhere between a sheet of paper and an eggshell, though I can't find a number for the Space Shuttle atm. Add to that a myriad problems, that this approach would bring... Concrete is porous, so air would escape, unless specially ...

15

The Long Duration Exposure Facility (LDEF) was a Shuttle-launched and -retrieved satellite designed to investigate exactly this. Here is the LDEF in space. It was covered in trays of different materials to investigate how they stood up in low Earth orbit. It was supposed to stay in orbit about a year, but the Challenger failure intervened, causing it to ...

14

With respect to potential travel in our own solar system there are two general types of radiation that have our concern! The first type of radiation is solar radiation, which mostly consists of low- to intermediate-energy protons, electrons and x-rays from our own star. We would shield against the protons with low molecular mass materials. Typically ...

14

The key material to produce to make plastics is the production of ethylene, which is $C_2H_4$. According to The Case for Mars, this can be produced by the reaction $2CO+4H_2 \rightarrow C_2H_4+2H_2O$, with the presence of an Iron catalyst.. And the carbon monoxide comes from $6H_2+2CO_2 \rightarrow 2H_2O+2CO+4H_2$. Thus, the key to making plastics on Mars is ...

14

Earth Carbon nanotubes might endure the enormous stress of an earth elevator but only short lengths have been manufactured so far. It would be a mega engineering project that would dwarf earlier human endeavors. An earth elevator would need to extend at least to geosynchronous orbit at about 36,000 km altitude. And unless there were a truly enormous ...

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 ...

13

At least for the Shuttle ET: The tank’s foam is a polyurethane-type foam composed of five primary ingredients: polymeric isocyanate, a flame retardant, a surfactant, a blowing agent, and a catalyst. A surfactant controls the surface tension of a liquid and thus cell formation. The blowing agent, HCFC 141b, creates the foam’s cellular structure ...

12

Yes - for silicone plastics. Mars does have plenty of silica (aka sand) so there are the basic materials to synthesize silicone - which can be used in place of most organic plastics. (Often performing better than conventional carbon-based plastics.) Methane, chlorine, water, and carbon-dioxide all exist on the surface as well. It should be stated that ...

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