Unanswered Questions

1,268 questions with no upvoted or accepted answers
22
votes
0answers
1k views

Where is the TEA-TEB stored for the Merlin engines onboard Falcon 9?

The Merlin 1D engines can restart up to four times, they use the pyrophoric mixture of TEA-TEB (Triethylaluminum-Triethylborane) to ignite the engines. My question is where is this stored in the ...
17
votes
0answers
336 views

Was Jules Verne the first to propose the retro-rocket concept?

In his novels 'From the Earth to the Moon', and 'Around the Moon', Jules Verne writes about a set of rockets fitted to the spacecraft he imagined, that were intended to be fired in order to slow down ...
16
votes
0answers
175 views

What is the current location of Link-built Apollo Mission Simulators?

There seems to be confusion about the final disposition of, and even the number of, Apollo Mission Simulators built by Link Flight Simulation Division. This question is not about any simulator built ...
15
votes
1answer
883 views

What is the value of the cross-track angle between the two designated CRS-4 first stage recovery zones?

For the SpaceX Falcon 9 launch on its Dragon/CRS-4 cargo delivery mission to the International Space Station, according to Spaceflight 101, two downrange safety zones have been identified: The SpX-...
13
votes
0answers
637 views

Does the FAA still license the people who fold human-rated reentry parachutes?

One of the links in the question International Orange? is the History.com article The Amazing Handmade Tech That Powered Apollo 11’s Moon Voyage which says of Apollo capsule re-entry and landing ...
13
votes
0answers
294 views

How did “the kid” (John Meisenheimer) calculate that there was a wave in the jet stream and Explorer 1 would be okay to launch?

The tough but timely question NASA at sIxty years, will there be a new moonshot mandate? links to the NASA YouTube video NASA 60th: How It All Began which shows a lot of really nice, historical file ...
11
votes
0answers
100 views

Why did SpaceX swap the LOX and CH4 tanks between Mk1 and SN1?

According to most sources, the Starship Mk.1 had its LOX main tank (not talking about the header tanks here) on top and its main methane tank below. But it seems the SN1 revision, and all subsequent ...
11
votes
0answers
178 views

Have there ever been any incidents where something valuable was unintentionally throw out with the trash?

In "What do astronauts do with their trash on the ISS?", a commentator asked the title question and was encouraged to make it a new question, but apparently never did. The linked question is ...
11
votes
0answers
165 views

What were the Top 10 Shuttle Risks in John Young's “famous letter”?

Whilst reading A Technical History of the External Tank I ran across this comment: Although the problem has not recurred, John Young, in his famous top ten Shuttle risk letter ...
11
votes
0answers
155 views

How does increased environmental radiation affect medication potency, long and short term?

The issue of the effects of radiation on medication potency is not only important for long term stays in the ISS, but also very important for longer duration journeys and even for colonization. One ...
10
votes
0answers
84 views

Why did GRACE mission have launch window?

GRACE mission which was launched on March 17th, 2002 had a 10 minutes launch window. The mission was to launch a couple of earth observation satellites. And interestingly, NASA's GRACE Launch Press ...
10
votes
0answers
411 views

How are the Voyagers' thrusters configured in a novel way to minimize accelerations along Earth-spacecraft axis?

I've just read in Eshleman et al 1977 Radio Science Investigations with Voyager that the voyagers have: ...a novel attitude-control thruster configuration that minimizes accelerations along the ...
10
votes
0answers
119 views

Is loss of flexibility a concern with crew on the ISS?

Videos of people on the ISS make it clear how little they need to bend or stretch, and how their joints stay in their neutral position most of the time as they float around - elbows, knees and hips ...
9
votes
0answers
77 views

Do Starlink satellites have cameras?

Obviously, Starlink satellites are equipped with sensors for attitude and location detection (like a star tracker or sun tracker) but I'm wondering if they have with any direct Earth observation ...
9
votes
0answers
137 views

Where in the Pale Blue Dot image should the Earth's moon be?

In the description of this image it is claimed that Moon should be detectable in famous "Pale Blue Dot" image. Detailed analysis also suggests that Voyager detected the moon as well, but it is too ...

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