58 votes
Accepted

What skipped test on Genesis would have detected the backwards-inserted accelerometer which didn't deploy the parachute?

The planned test was a centrifuge test. They were going to take the entry vehicle up past the 10-g mark and back down. According to the JPL Mission Manager, who was my boss at the time, the g-switch ...
Tom Spilker's user avatar
  • 18.3k
54 votes

Why is the supply of RTGs running short?

The Plutonium isotope 238 used in RTGs is highly specialized. It's not produced in large quantities routinely. Not very many radioisotope applications need that much of a highly radioactive isotope, ...
ikrase's user avatar
  • 8,899
42 votes
Accepted

What makes aluminum aerospace grade?

Read David Hammen's comment below the question. Once you get past the (well deserved) sarcastic humor he absolutely nails the answer. There is no checklist for getting an alloy of anything to be ...
BradV's user avatar
  • 3,162
34 votes
Accepted

How does one throw a boomerang in space? Does it return?

You throw it in space (in the ISS) just like you would in a room on Earth. It returns to you if it is properly built, and you are capable of properly throwing a boomerang to make it return (this does ...
JRE's user avatar
  • 813
33 votes

Why are there four RTGs in a row sitting in this room? What are they waiting for? Were they built together and stored for separate launches?

There were seven General Purpose Heat Source - Radioisotope Thermal Generators (GPHS-RTGs) assembled (there were parts for an eighth). The seven would eventually fly in space on four different ...
Organic Marble's user avatar
27 votes

Why is the supply of RTGs running short?

Any isotope used as the basis for a radioisotope thermoelectric generator (RTG) has to have a short but not too short half life. A half life of several decades is ideal. Such isotopes effectively do ...
David Hammen's user avatar
  • 74.2k
16 votes
Accepted

Which Apollo-era contractors are still building aerospace components today?

The following figure helps summarize most of the many mergers that have happened in the aerospace industry. However, it does not show the 2020 merger and split between UTC and Raytheon. AC Delco: ...
15 votes
Accepted

What is "aerospace grade"?

If sometimes aerospace grade and non-aerospace grade parts are the same exact thing then what makes one aerospace grade and one not? Sometimes is the key word here. They happen to be the same, ...
David Hammen's user avatar
  • 74.2k
14 votes

Why is the cubesat structure so expensive?

It's expensive because of the quality requirements. Material cost is small, low demand is a factor but a structure that size can be made much cheaper than this. The main cost factors are : The ...
Hobbes's user avatar
  • 127k
14 votes

Why is the supply of RTGs running short?

It's not just the half-life of the material (short enough to make heat, long enough to have a slow changing energy curve) It's also the type of radiation. For instance Cs137 is plentiful and easy to ...
Harper - Reinstate Monica's user avatar
12 votes

How does one throw a boomerang in space? Does it return?

The return function of a boomerang works in the atmosphere only. Therefore no return in the vacuum of space. The 'arms' of a boomerang are profiled like a airplane wing, but wings do not work without ...
Uwe's user avatar
  • 48.9k
12 votes
Accepted

Recycling space debris for manufacturing in space

No doubt this is possible, but it is not practical. The main problem being the vast array of different orbits available and the high energy cost to move between many of them. In most cases it would be ...
Slarty's user avatar
  • 9,212
11 votes

Recycling space debris for manufacturing in space

The previous answers are wrong. Moving stuff between two reasonably similar orbits is actually much less energy-intensive than launching up the same mass right to the intended orbit. And indeed any ...
leftaroundabout's user avatar
10 votes

Why are the SpaceX Starship, "rings" the width that they are?

The largest commercially available width of a roll of stainless steel in the United States is 72 inches. Apparently this is a standard size, and getting something larger would be a custom order, and ...
geoffc's user avatar
  • 79.4k
9 votes
Accepted

Why do these satellite antennas look so weird? (strangely shaped with little white dots...)

The irregular shape of the reflector is to shape the beam coming from feed in such way that it is tailored to match the contours of geographic region of service area. Here's a short paper on shaped ...
Ohsin's user avatar
  • 1,742
8 votes
Accepted

Was CNC milling used in the 1960's for making the Apollo/Saturn rocket engines?

At least some parts for the Apollo program were CNC-machined: e.g. the frame of the flight computer. I haven't found any documents that confirm CNC-machining was used on the F1, though. On one hand,...
Hobbes's user avatar
  • 127k
8 votes

What hardware does SLS actually share with STS?

Partial answer The SSMEs / RS-25 are mostly reused but some parts have been redesigned. (Since SLS expends the RS-25s, in the unlikely case that it flies a lot, they plan to gradually improve new ...
Organic Marble's user avatar
8 votes

What makes aluminum aerospace grade?

While it has been implicitly explained in other answers, I don't think it has been spelled out explicitly yet: what makes aluminium "aerospace-grade" has nothing to do with the aluminium ...
Jörg W Mittag's user avatar
7 votes
Accepted

Who were the major manufacturers of the Apollo 11 rocket?

Here are the major contractors for the Saturn V launcher and Apollo spacecraft: Saturn V first stage: Boeing Saturn V second stage: North American Aviation (now part of Boeing) Saturn V third stage: ...
Russell Borogove's user avatar
7 votes
Accepted

How much of SpaceX's Falcon 9 launch vehicle and Dragon capsule are 3D printed?

Additive manufacturing has a high payoff for complex parts that are hard or impossible to machine using traditional methods, however, the process often requires significant trial and error to get ...
Sifu Yee's user avatar
  • 557
7 votes
Accepted

What is the cost of production or sale of a Soyuz spacecraft?

Probably all that can be found is the total value of the contract - USD35,575,564 Договор на выполнение работ по изготовлению и сборке отсеков, сборке, проведению работ на КИС и сдаче ТПК «Союз МС», ...
A. Rumlin's user avatar
  • 7,873
7 votes
Accepted

Rad-Hard vs Space-Hard computing

Every computational device used in space has to be tolerant to vibrations. Launch is a very shaky process. Every computational system used in space has to be tolerant of various forms of radiation. ...
David Hammen's user avatar
  • 74.2k
7 votes

What is "aerospace grade"?

Materials science over centuries has known that materials properties can vary widely with subtle differences in composition, processing, heat treating, etc. Because aerospace products like aircraft ...
BradV's user avatar
  • 3,162
6 votes
Accepted

What makes a payload fairing so expensive?

They are expensive because the manufacturing process is complex. In this video, there is a good section explaining how those structures are built: NASA 360 - Composite Materials. Very complex and ...
hshib's user avatar
  • 609
6 votes

Satellite manufacture and cleanliness

This answer is speculation, but speculation based in personal experience in satellite clean rooms. Space hardware is frequently subject to unusually restrictive constraints. Some examples that other ...
Bear's user avatar
  • 1,565
6 votes

What makes aluminum aerospace grade?

"Aerospace grade" is a marketing term that has no actual meaning. This means that there is no actual difference, in the material, at least theoretically. I think that the question and the ...
user47347's user avatar
6 votes

What is "aerospace grade"?

These days the term aerospace grade "has come to be a fashionable marketing slogan for luxury goods". Originally however, it had it's origins in specifications required for military ...
Fred's user avatar
  • 13.1k
6 votes

Using orbital construction around another body to build probes

It's not possible at this time. Humanity has no experience in building a dollar-store-quality hammer from raw materials on any non-Earth body, much less a space probe. If it were possible to ...
notovny's user avatar
  • 5,429
5 votes
Accepted

Was this the only time that helium balloon was used to support deployed spacecraft appendages during testing on the ground in Earth gravity?

For mobility tests of ISRO's Pragyan rover that was part of Chandrayaan-2 lunar orbiter/lander campaign they used a large Helium balloon to counteract 5/6 of Earth's gravity. These tests were ...
Ohsin's user avatar
  • 1,742
5 votes

What is "aerospace grade"?

The other answers have missed the direct answer... The Society of Automotive Engineers (SAE) has created a list of standards for all sorts of materials, procedures, processes, etc... related to ...
noslenkwah's user avatar

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