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
268 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 ...
13
votes
0answers
133 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
190 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
297 views
+100

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
215 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
198 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
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0answers
296 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
156 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
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0answers
234 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
903 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 ...
9
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0answers
91 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
104 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
154 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
106 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
184 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
188 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
372 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
141 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 ...
8
votes
0answers
302 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
365 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
990 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
315 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
183 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
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0answers
188 views

What is NASA doing to improve the supersonic parachute for the third LDSD test?

Last month, on June 8, 2015, NASA ran the second Low-Density Supersonic Decelerator (LDSD) flight test off the island of Kauai, Hawaii. The inflatable decelerator portion of the test was successful, ...
8
votes
0answers
398 views

Current Research Being Done on Hall Effect Thrusters

It seems like electric propulsion will be the most viable candidate for current and future interplanetary missions. However, I was wondering what type of research is currently being done on Hall ...
8
votes
0answers
521 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
115 views

What's the sudden pitching of Rocket Lab's It's Business Time launch at separation?

In today's Rocket Lab launch of the It's Business Time mission, there was a substantial and swift change in attitude upon stage separation. It looks scary. I understand that The first stage of a ...
7
votes
0answers
82 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
80 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
163 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
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0answers
194 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
105 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
156 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
167 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
298 views

How might one approach using AI (convolutional neural network) to predict collisions in orbit?

CNN's Tomorrow's Hero profile Meet Amber Yang. She's trying to prevent a space debris catastrophe describes an investigation into the use of a convolutional neural network (CNN) to predict possible ...
7
votes
0answers
506 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
66 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
247 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
326 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
167 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
518 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 ...
7
votes
0answers
467 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 ...
7
votes
0answers
154 views

Why is there no common “docking” interface for express rack payloads?

It seems strange to me that given all of the concerns about living space and color palette aboard ISS, the data/power/cooling ports for different mid-deck locker equivalent (MLE) express rack payloads ...
7
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0answers
108 views

Did SpaceX use TDRSS or USAF ground station to track Falcon 9 stage 2?

Which system did spacex rely to? Falcon, not dragon
7
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0answers
177 views

Why did the frequency of TLEs for the Hubble Space Telescope drop by a factor of 3 in 2009?

I noticed that the TLEs for the Hubble Space Telescope (HST) are posted almost twice a day. Then I looked back in time and saw that this rate varies quite a lot! The plot shows the time interval ...
7
votes
0answers
140 views

What is the maximum velocity for feathered reentry systems?

I gather that the Virgin Galactic planes use feathered reentry systems with a maximum velocity of about 1.4 Mach, or about .5 km/s. I understand this won't work from full orbital speed, 7km/s, because ...
7
votes
0answers
277 views

What makes materials on the Moon look so different when the sun is high?

The surface of the Moon looks very different in orbiter images taken at local noon than it does in images from other times. Here are two examples of the same places in Lalande Crater. In each image, ...
7
votes
0answers
123 views

Smart suits in development

This is an offshoot of this question. There's a new generation of space suits coming up (Z-series, anything that the Zvezda NPP has up its sleeves), and I wonder at the level of sophistication of ...

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