All Questions

19
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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 ...
14
votes
0answers
259 views

Has SpaceX ever done a hot restart of a 2nd stage?

Another question highlighted this Space X commentary for the GRACE-FO launch: Now in order to fly an efficient trajectory for both of the payloads, we’re actually now running the second stage ...
13
votes
0answers
217 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?

This tough question links to the NASA YouTube video NASA 60th: How It All Began which shows a lot of really nice, historical file footage and stills. After about ...
11
votes
0answers
135 views

Human-rating the Saturn V using modern standards

Would a complete Apollo-Saturn stack (like e.g. AS-506) be human-rated according to the latest human-rating process (NPR 8705.2C) of NASA? If not, what are the biggest show-stoppers? This question ...
11
votes
0answers
142 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
202 views

What were the hammerhead cranes used for?

During Apollo, the three Launch Umbilical Towers had a hammerhead crane at the top: Until 1994, the Space Shuttle's Fixed Service Structures were topped by literally the same cranes. The linked ...
10
votes
0answers
492 views

Why does the YF-75D nozzle have such a strong spiral pattern?

Why does the YF-75D nozzle material have such a strong spiral pattern? Is it a result/biproduct of a manufacturing process only, or does it have some specific function? edit: The last, cropped ...
9
votes
0answers
79 views

Detailed information about the Soyuz descent module connection box?

Anyone have some detailed information about how all this connectors, located in the soyuz descent module? Are they used only when they setup the Soyuz or they are ...
9
votes
0answers
134 views

Where are the Apollo forward heat shields currently located?

The Apollo Experience Report: Thermal Protection Subsystem explains that there are three sections to the Apollo heat shield: The aft heat shield, at the "base" of the cone and adjacent to the SM. ...
9
votes
0answers
134 views

28V vs. 124V on the ISS

Apparently the US segment of the ISS runs on 124v DC, while the Russian segment is on 28v DC. Why the difference? I understand it is often safer to have several different voltages rather than one, but ...
9
votes
0answers
143 views

What's the role of the chainmail and scale armor on InSight's WTS?

It's like taken directly from a medieval armor... The role of wind and thermal shield (WTS) deployed over the seismometer is in its name - protecting it from noise and thermal changes. This is fairly ...
9
votes
0answers
351 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 ...
9
votes
0answers
422 views

What would have been the absolute maximum LEO payload of a two-stage Saturn V?

I read about the Skylab 1 mission in which SA-513 was used to lob the Skylab OWS into orbit. One source (http://forum.nasaspaceflight.com/index.php?topic=12519.20) gave some payload masses: Total ...
9
votes
0answers
331 views

How do domes in lunar impact melts develop, and might they be hollow?

On the floors of young craters of the Moon, smoothly rounded domes are visible in some spots. Lalande crater has 4 of them, each around 200 m across. Here are less regular ones on the floor of ...
8
votes
0answers
101 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 ...
8
votes
0answers
98 views

Is the vestibular system ever useful in spaceflight?

The Vintage Space video Eleven Deaf Men Helped NASA Leave Earth describes a number of different NASA experiments done on human subjects who had damaged vestibular systems due to childhood illness. ...
8
votes
0answers
106 views

At what surface gravity can't astronauts do full steps anymore?

We know that on the Moon in ~1/6 g the Apollo astronauts couldn't make full steps because they jumped with each step. At what surface gravity could you walk more like on Earth and at what gravity ...
8
votes
0answers
303 views

Purpose of side holes on SuperDraco pods of DM-1 flight Dragon 2 capsule

I've watched the launch video for DM-1 today, and one thing caught my attention. On SuperDraco pods, below the plugged SuperDraco engine openings, there are two more plugged holes. I've marked them on ...
8
votes
0answers
62 views

What science data has been released from Chang'e 4?

Chang'e 4 was the first soft landing on the far side of the moon. What science data has been released from it? That is, in two parts: what science was done and of that, what data has been released to ...
8
votes
0answers
136 views

Was this the first-ever photo of a full moon very close to lunar new year?

Limiting the concept of "lunar new year" to "Chinese New Year" (since there are many lunar and lunisolar calendars, the latter of which the traditional Chinese one is a widely used example), is this ...
8
votes
0answers
420 views

Why isn't stainless steel used for rocket engines?

Most people have probably heard by now that Elon is changing Starship to a complete stainless steel build. Anyways, it got me thinking, why isn't stainless steel ever used for rocket engines (nozzle, ...
8
votes
0answers
94 views

What is the sensor used for Soyuz booster separation?

Roscosmos released their findings of the aborted Soyuz-to-ISS launch, blaming it on a separation sensor that had a deformed pin. What is this sensor? It sounds like an electrical plunger switch, but ...
8
votes
0answers
171 views

Was Jules Verne the inventor of the retro-rocket?

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 ...
8
votes
0answers
228 views

Documented economics of STS Solid Rocket Booster reuse?

I often see the claim that the Shuttle SRBs cost as much to recover & refurb as it would to build a new one. I've probably even parroted this claim myself. But, are there any actual studies or ...
8
votes
0answers
288 views

Why was the Apollo 6 service module painted white?

All other SM's were silver except Apollo 6. I'm wondering what the justification for this was, if any?
8
votes
0answers
314 views

What exactly is the interaction that blocked Juno's data downlink near solar conjunction?

According to Space.com's article Juno Phones Home: Jupiter Probe Reconnects with Earth After 8th Flyby, Juno's recent close flyby of Jupiter and data collection happened while Jupiter was too close to ...
8
votes
0answers
581 views

Roughly how many self-viewing cameras are present in a Falcon 9 LEO mission?

Watch any of last year's SpaceX LEO satellite deployment missions's broadcasts in YouTube, and you can see views from at least several different cameras. At least two on the 2nd stage nozzle, at least ...
8
votes
0answers
101 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 ...
8
votes
0answers
563 views

How strong is the electric charge capacity of Martian dust storms?

In my answer to What would it feel like to be in a Martian dust storm? I assert that Martian dust storms would be best avoided, and as one of the reasons (besides carrying corrosive chemicals like ...
7
votes
0answers
126 views

Project Mercury capsule switch orientation

I noticed that the majority of the toggle switches in the Mercury capsules move in a left-to-right manner. This seems unusual to me, since Gemini, Apollo and the Shuttle all predominantly use up-down ...
7
votes
0answers
264 views

Why is SpaceX's Raptor's design so simple in comparison to SSME?

What is especially striking to me is how simple Raptor is in configuration compared to SSME. The Raptor doesn't have an LP fuel or oxygen pump. What's even more surprising, if we are to compare the ...
7
votes
0answers
76 views

Method for keeping surface water on mars?

I've been reading this wikipedia article on terraforming mars. One of the major issues with terraforming mars is essential molecules and elements escaping the planet. There have been several ...
7
votes
0answers
58 views

Does the kinetic impact of gas particles cause erosion to the surface of objects in orbit?

When satellites or space stations orbit the Earth, they are constantly experiencing a low level of aerodynamic drag from Earth's atmosphere. The ISS needs to be reboosted every few months to account ...
7
votes
0answers
216 views

Why ISS Astronauts have red stripes?

After seeing the interesting question How do ISS astronauts “get their stripes”?, I was wondering why the color red was chosen for the identifying stripe: I am assuming that red is the best color ...
7
votes
0answers
155 views

What's the shiny triangular feature on this Progress vehicle?

Picture from here What's the shiny, slightly curved triangular plate with rails above it? A larger version, cropped from here, thanks to a comment by ohsin.
7
votes
0answers
92 views

How are co-located satellites positioned relative to each other?

I'm trying to learn about co-located GEO satellites. When I first heard about them, coming from a planetary orbital mechanics background, the first thing I pictured was based on the epicyclic ...
7
votes
0answers
1k views

What colors were used in the Apollo Lunar Module interior, and why?

There are lots of publications and blog posts on the exterior colors of the Apollo Lunar Module (a function of material choices), but I've struggled to find any information on the interior colors and ...
7
votes
0answers
168 views

What is Tiangong-2 doing?

Some news in various outlets following some twitterings including this tweet by Jonathan McDowell about Tiangong-2 performing a sizeable orbit-lowering, followed by a re-raising: ‏ OK now that's ...
7
votes
0answers
115 views

Why was the “Presidential Panorama of Mars” called presidential?

From The Astronomy Picture of the Day for 2000 May 14 : Explanation: Scroll right to unfold one of the great panoramas ever taken on the surface of Mars. For best viewing, click and hold the right ...
7
votes
0answers
215 views

What spinoff technologies have come from the Soviet/Russian space program?

There is plenty of information available on NASA spinoff technologies including a Wikipedia page and Space SE question. What innovations are a byproduct of the Russian space program?
7
votes
0answers
275 views

Common Berthing Mechanism Dimensions

I've found detailed information on the International Docking Standard, enough to start work on a detailed CAD of the mechanism. (http://www.internationaldockingstandard.com/download/...
7
votes
0answers
173 views

Onboard recording of trans-Mars injection

Is there any video recording of the Falcon Heavy trans-Mars injection burn from onboard cameras? The live feed of the Tesla Roadster and Starman orbiting Earth cycled through multiple cameras ...
7
votes
0answers
299 views

Launchpad platform structural design

I am a civil engineer and would like to do a study on the design and construction of launching platforms for large lift vehicles, one example of which is the ELA 3 (Ariane Launch Area 3) in French ...
7
votes
0answers
74 views

Implementing control system to track position and velocity references simultaneously

I've been trying to implement a PI (proportional-integral) controller to allow a launch vehicle to track 2 reference states simultaneous, namely position and velocity, so that the launch vehicle will ...
7
votes
0answers
106 views

Is anything being done to honor Gene Cernan today? (14 Dec. 2017)

14 December 1972 05:40:56 UTC US astronaut Gene Cernan returned to the Apollo 17 Lunar Excursion Module, becoming "the last man on the Moon" for forty-five years, so far. (as reported in my Space ...
7
votes
0answers
126 views

How much delta v is required to keep a low Lunar orbital station stable?

I'm interested in studying where in Lunar orbit a station could be deployed. Due to mascons, Lunar orbits below about 200km will eventually decay according to this answer. Presumably, if the goal of ...
7
votes
0answers
262 views

Have LAGEOS' germanium corner cube reflectors ever been used?

When I was writing this answer about the LAGEOS satellites, I notices that four of the over four hundred corner reflectors are made of optical germanium rather than fused silica. Fused silica (FS) ...
7
votes
0answers
209 views

Have there been at least continuous periods of plants growing on the ISS?

I know there have been some experiments in hydroponics that are addressing issues related to growing significant quantities of food and even fresh vegetables in space in the future. I was wondering; ...
7
votes
0answers
409 views

Can you enjoy a cold carbonated drink in space?

I will grant that launching a can of soda pop, or beer into space would be very expensive. Alternately it is not unreasonable to make it in the space station, carbonated drink makers are easily ...
7
votes
0answers
334 views

Understanding formula for geocentric position of Moon

I am trying to understand a basic formula in a Celestial Mechanics reference. The formula is for the position of the Moon in a geocentric frame. The reference claims in line (981) that this should be ...

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