Community Digest

Top new questions this week:

Would replacing a damaged tank have prevented the Apollo 13 incident?

In Oct. 1968, at North American works, one Oxygen tank was dropped from a height of 2 inches, (perhaps on the fill valve side) and this dropping damaged the fill valve. Because of this, this ...

apollo-13 fire cddt  
asked by Niranjan 19 votes
answered by PcMan 33 votes

What is this pin on John Glenn's suit jacket?

I'm watching the documentary "The Real Right Stuff". Around the 14 minute mark they show a clip of a news interview of the 7 mercury astronauts describing how their family feels about them ...

history identify-this-object project-mercury  
asked by KDecker 18 votes
answered by Organic Marble 33 votes

What is an "octet" in the context of NASA's LunaNET Interoperability Standard? ("internet on the Moon")

The PDF Draft LunaNet Interoperability Specification, LN-IS Baseline V001 September 2, 2021 (found at has found its way to the popular press. 4.2 ...

the-moon communication terminology artemis-program standards  
asked by uhoh 16 votes
answered by Jörg W Mittag 33 votes

How does SpaceX plan to supply or recycle respiratory gasses?

If Starship carries 100 passengers to Mars, they will consume about 6 metric tons of oxygen and produce about 10 tons of CO2 on each leg of the trip. Much more if they exercise. CO2 could be converted ...

spacex spacex-starship life-support isru  
asked by Bruce Woodburn 13 votes
answered by Jörg W Mittag 17 votes

Why don't Raptor engines use CH3Cl instead of CH4?

The boiling point of CH3Cl is -24 degrees Celsius, whereas the boiling point of CH4 is -160 degrees Celsius. The density of CH3Cl is 2.3 g/cm3, whereas the density of CH4 is 0.6 g/cm3. CH3Cl is polar, ...

spacex mars fuel  
asked by Mhd Afz 11 votes
answered by PcMan 36 votes

Thorium in space

I am looking at the possibility of future space habitats being powered by Thorium. Main question is where to get Thorium? Could there be a metallic asteroid (like 16 Psyche) that contains Thorium and ...

asteroid thorium  
asked by Calcutta 8 votes
answered by Christopher James Huff 10 votes

What is the deepest part of the moon on the near side?

Per title, I must emphasize that it shall be on the near side. Antoniadi (lunar crater) and Aitken basin are all on the far side. Preferrably it is also wide and large like the Oceanus Procellarum...

the-moon lunar-base crater  
asked by Kav 7 votes
answered by kim holder 15 votes

Greatest hits from previous weeks:

Do the planets really orbit the Sun?

We often say that the planets orbit the Sun, which is usually a reasonable approximation. But in reality both Sun and the planets orbit the center-of-mass/center-of-gravity of the whole solar system, ...

gravity solar-system  
asked by CodesInChaos 124 votes
answered by Vedant Chandra 154 votes

How tall do you have to be to be an astronaut?

Currently I am 13 years old and the thought of space amazes me. I am 5 feet 7 inches (1.7 m) tall. I researched how tall you had to be to be an astronaut. Sites agreed and disagreed, throwing out a ...

astronauts health astronaut-recruitment  
asked by Mac Vibrant 34 votes
answered by Phiteros 38 votes

Current position of Starman

Have looked at current videos of Starman and not found data as to it's current position. Is there a site plotting the current position of Starman?

spacex trajectory interplanetary tesla-roadster  
asked by Ted Lawson 12 votes
answered by PearsonArtPhoto 12 votes

Is this egg-shaped nose cone a good, aerodynamic design?

So Jeff Bezos has recently travelled to space aboard an Amazon-funded rocket, which has an unusual, egg-shaped nose. However, just about every other rocket I've seen has more of a cone-shaped nose, ...

rockets aerodynamics  
asked by AJFaraday 16 votes
answered by PcMan 24 votes

If an astronaut threw a cup of coffee into space, would it freeze, or boil off into gas?

If an astronaut threw a cup of coffee into space somehow, would it freeze into a block, or boil off into gas due to the zero pressure?

physics water temperature vacuum  
asked by James from NZ 36 votes
answered by Uwe 56 votes

How stable would a Falcon 9 first stage be after it has landed on a drone ship?

Presumably, the booster would be a very light, very tall tube (Most of the fuel spent) standing on 4 fairly small legs on a ship in the middle of the ocean. It would also still contain some LOX and ...

spacex reuse falcon-9 first-stage  
asked by neelsg 20 votes
answered by TildalWave 13 votes

What thickness/depth of water would be required to provide radiation shielding in Earth orbit?

If using water or ice as a radiation shield how thick/deep would it need to be? Would it make a difference if the water was frozen (water ice being less dense then liquid)? Edit I would like to ...

radiation space-station water  
asked by James Jenkins 32 votes
answered by KeithS 27 votes

Can you answer these questions?

Could not an adapted RASSOR appear to be crucial for the Perseverance rover to find possible biosignatures on Mars?

Is it not very likely that most of the material that could contain possible biosignatures, like clays and carbonate containing minerals, will be below a layer of dust or regolith on Mars ? That the ...

mars design-alternative perseverance astrobiology  
asked by Cornelis 3 votes

Are there examples of spaceflight equipment being redesigned to remove right hand bias? (To make it less difficult to use left-handed)

Writing First left-handed primate on the Moon? First in space? got me thinking. The first left-handed astronaut may "break a barrier" but not all barrier-breakings result in an improvement ...

crewed-spaceflight astronauts spaceflight-firsts equipment  
asked by uhoh 3 votes

Where can I read about the other 17 telescope proposals that NASA’s Astrophysics Explorers Program didn't accept in 2019?

Scitech Daily's NASA Selects Gamma-Ray Telescope To Probe Origins of Galactic Positrons, Chart Milky Way Evolution says: NASA has selected a new space telescope proposal that will study the recent ...

nasa space-telescope reference-request  
asked by uhoh 2 votes
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