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 ...
16
votes
0answers
350 views

Why is the exhaust plume of Falcon 9 upper stage shaped the way it is?

The (single) Merlin 1D vacuum engine's exhaust plume has a symmetric shape, comprising of six distinct "inner" plumes. Why does it have this shape? Is it due to the shape/configuration of fuel ...
14
votes
0answers
142 views

When have secondary payloads damaged the primary payload of a launcher?

Primary payload customers have traditionally been cautious when allowing secondary payloads on the same launcher. For example, a secondary payload is not trusted to have its own chemical propulsion ...
11
votes
0answers
200 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 ...
10
votes
0answers
919 views

How does JAXA's “Int-Ball” manage airflow to optimally navigate inside the ISS?

above: From the BBC's Japan's zero-gravity space drone sends first pictures from ISS. This is JAXA's GEM internal ball camera, or "Int-Ball". Kawaii! It looks like it uses a three axis attitude ...
10
votes
0answers
331 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
446 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 ...
10
votes
0answers
243 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 ...
9
votes
0answers
210 views

How is Dragon-v2 prepared for being docked for months at ISS?

The Dragon spacecraft is being certified for manned spaceflight. If it's to replace Soyuz, though, it will have to serve as an escape pod for the crew. The current delivery missions are proving its ...
9
votes
0answers
317 views

Does the “17” really mean anything with respect to GNSS orbits being rational factions of a sidereal day?

This answer suggests that the orbital periods of the four large GNSSS contstellations are linked to the sidereal rotation period of the earth by rational numbers with 17 or 34 as the denominator in ...
9
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0answers
187 views

How far have autophage rockets been developed?

Ars Technica reports on a May 24 phys.org press release/precis on a University of Glasgow paper in Journal of Spacecraft of Rockets about a solid rocket intended to consume itself during use rather ...
9
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0answers
164 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 ...
9
votes
0answers
254 views

What were some of the first two stage rockets flown?

The first US two stage rocket was bumper, a combination of a german V2 liquid fuel rocket with an US second stage. The Soviet Union had the R-1 and R-2 based on the V-2. In this list, the R-7 is the ...
9
votes
0answers
94 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
229 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
129 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 ...
8
votes
0answers
148 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
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0answers
178 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
112 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 ...
8
votes
0answers
190 views

What was happening with the DSN/ Cassini?

I decided that I wanted to see DSN receive the last bits of data from DSN Now. The last data was supposed to be received at about 7:55. The signal seemed to continue strong until about 10 minutes ...
8
votes
0answers
199 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; ...
8
votes
0answers
386 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 ...
8
votes
0answers
315 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 ...
8
votes
0answers
566 views

Is there any compiler available for HAL/S?

The HAL/S programming language is used in the general purpose computers in the space shuttle. I have written a simple HAL/S program of my own. Is there any compiler available to turn it into ...
8
votes
0answers
380 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 ...
8
votes
0answers
1k views

How many astronauts are left handed?

One kind of 'popular science' fun facts that is very popular is to show how many of the individuals belonging to a notable group of people that are left handed, often showing a large disproportionally ...
8
votes
0answers
323 views

What caused this shadow on Falcon 9 stage 2 w/Jason-3 before circularization burn?

While the image appears bright, the light is just reflected sunlight (from the earth, per the webcast). The circularization burn doesn't start until about T+ 00:55:16 per the SpaceX webcast. But at ...
8
votes
0answers
185 views

Are the surfaces in permanent shadow in Moon craters 'fluffy'?

I was talking to someone who anticipated digging for water ice and other volatiles would be easy in these areas because Pete Schultz of the LCROSS science team described them as 'fluffy'. In this ...
8
votes
0answers
551 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
93 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 ...
7
votes
0answers
54 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
188 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
147 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
241 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, ...
7
votes
0answers
86 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 ...
7
votes
0answers
86 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
166 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
234 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?
7
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0answers
110 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
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0answers
193 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
169 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
568 views

ISS - Tiangong 2 minimum safe distance

Using the SGP4 propagator, I calculated the minimum distance between ISS and Tiangong-2 for this year. I obtained 12.32 km for 2017-09-27 17:29:36.376 UTC (which is the day 270.7289). I used the TLE ...
7
votes
0answers
72 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
72 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
251 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
388 views

Will we all be in voluntary ketosis on Mars?

The EurekAlert! NASA mission tests ketogenic diet undersea, simulating life on Mars University of South Florida researcher will be in nutritional ketosis during NEEMO 22 mission packs a lot of ...
7
votes
0answers
299 views

Why NASA's sudden (apparently) interest in Wax hybrid engines? Which property is so attractive now?

I've just read the NASA news item From Pedicures to the Peregrine Rocket, Paraffin Wax Proves Its Worth. The project started when researchers at Stanford discovered that paraffin fuel burns three ...
7
votes
0answers
169 views

Spinning in space to manage gas?

A recent comment pointed out you can't burp in zero-g, while we don't have anything here about it, a Google search seems to support the comment. If you spin your body, in theory you could overcome ...
7
votes
0answers
149 views

What goes into the planning and execution of the deployment of groups of LEO satellites?

I was among many watching SpaceX's exciting OrbComm-2 mission (Falcon-9 Flight 20, 22-Dec-2015), and besides the first successful landing of a 1st stage after an orbital mission, the deployment of the ...
7
votes
0answers
484 views

How is retropropulsion by the Falcon 9 first stage being used to design retropropulsion entry on Mars?

Much has been made of how the reentry burns of Falcon 9 first stages occur at an altitude where the atmosphere is similar in density to the atmosphere of Mars, and so they demonstrate that supersonic ...

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