Newest Questions
19,643 questions
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Implementing burns in a GMAT python API loop
I am trying to create a loop in the GMAT Python API that executes an impulsive burn after each timestep.
...
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1
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0
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20
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FoV Determination (in STK)
I need to calculate the field of view (FoV) of a satellite in LEO (600 km orbit). I am using STK, however, if I create a cone, I cannot determine what is really the max. FoV covered by the satellite. ...
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9
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2
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654
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First successful use of an imaging chip (e.g. CCD) in space?
Continuing a series of spaceflight-firsts questions, I'd like to know; what was the first successful use of a solid-state, digital imaging chip in space.
I'm also curious if it was on a deep space ...
- 154k
2
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1
answer
53
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History, usage, and redundancy(?) of the three "draggy" TLE parameters that can lower orbits?
After writing two answers, then having second thoughts, then reading Revisiting Spacetrack Report #3: Rev 3 I've decided that I don't know anything.
The first line of a TLE has three parameters that ...
- 154k
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1
answer
196
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If modern space capsules don't have a parachute bail out system the way the shuttle did why do astronauts still train for parachute jumps into water?
Or do they not and only other aspects of water survival? I've seen them being dropped into the NBL from height on recent resource reels.
Source:
- 2,590
2
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1
answer
53
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High Order and Degree Gravitational Potential and correlation with Orbit Propagation Error
I am trying to get a good understanding of when to use higher order/degree gravitational terms in orbit propagation, but I am coming up short on any literature that measures or highlights the ...
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2
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1
answer
101
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At which altitude is B* neglectable?
Obviously, B* is an arbitrary number only used as a crutch for orbital propagators, but I was wondering for which orbits is it useful or starting with which altitude it can be neglected? In terms of ...
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79
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How would an Apollo LM crew have determined which abort mode to use when attempting to land?
I have read a great deal about procedures for Apollo missions, and read much of the online Apollo Flight Journal and Apollo Surface Journal transcripts. When discussing the decision to abort a landing,...
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1
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Do all astronauts train in the NBL or only those who will actually be taking spacewalks?
I'm asking out of curiosity. It would make sense if they did even if they trained for general EVA operations and if they wouldn't actually be performing a spacewalk didn't do mission specific EVA ...
- 2,590
11
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1
answer
2k
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Do mission specialists need to solo the t38 as part of their training?
Or are they only ever backseaters during their space flight readiness training in it? I understand they don't need to log anywhere near as much time in it as pilot astronauts do but they do have a few ...
- 2,590
5
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1
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131
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Struggling to simulate orbital geometry for a constellation of sun-synchronous satellites
I'm very new to simulating satellite propagation - my research is in atmospheric science but I need simulate a constellation of sun-synchronous satellites for observational research. I have been told ...
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2
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149
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is MethaneSat's location presently known or unknown?
The BBC's July 4, 2025 $88m pollution-tracking satellite missing in space headline is catchy, and the BBC News generally does a good job with headlines - keeping them catchy and clear but not over-the-...
- 154k
8
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1
answer
2k
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What are these scoops on the Saturn V first stage?
This is an image taken of the Saturn V on display at the U.S. Space and Rocket Center.
Highlighted in the image is a sort of scoop attached to the engine cowl. It is placed such that it will impinge ...
- 3,763
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69
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Could an earth sized world exist at the third Lagrange point? [duplicate]
Could an earth sized world exist at the third Lagrange point? Would it and earth affect each other's orbits in any way?
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1
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171
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What was the organizational structure of Space Shuttle launch preparations?
Launching hundreds of times must have gone hand in hand with a well established data review process and 'authority to proceed' checkpoints from various subsystems.
I am interested in the ...
- 3,763
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3
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2k
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Have automated systems ever been proposed for repairs to the exterior of a spacecraft?
Have systems to enable autonomous (or at least astronautless) repair of exterior damage to a spacecraft ever been developed or considered?
Would spider like robots or astromechs have a practical place ...
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2
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142
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Knowledge needed to start rocketry hobby [closed]
I am a physics and rocketry enthusiast. I have the 9th Edition "Rocket Propulsion Elements" by George P. Sutton which is 700+ pages of professional and useful knowledge on rocketry and ...
3
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61
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Is there any propellant for which a diverging-only nozzle would make sense? [duplicate]
It's been more than 15 years since I took Thermodynamics of Propulsion. By my recollection, a de Laval / converging/diverging nozzle accelerates a subsonic high pressure gas stream in the converging ...
- 17.7k
12
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2
answers
1k
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Optimal transfer to Jupiter?
Playing around with the Nasa trajectory tool I noticed that optimal transfers to Jupiter (from 2010 to 2040) all follow the same pattern:
get into an eccentric orbit (2 AU)
at aphelion do a deep-...
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0
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73
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From how far away would we be able to detect alien use of nuclear pulse propulsion? [closed]
I heard it would produce telltale gamma rays and we would know said gamma rays weren't coming from our own activity or from natural GRBs.
- 2,590
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1
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194
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Lambert's theorem violated?
Let's assume we start at a given location $p$ in space around a central body. After one orbit and time $T$ we arrive again at $p$. But how many trajectories taking also time $T$ are there to return to ...
- 564
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Converting ECEF acceleration to ECI in Astropy?
I am using Astropy to convert between and ECEF frame and an ECI one, I can do this happily with position and velocity by creating a CartesianRepresentation object with the ECEF position and velocity ...
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3
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169
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Orbit insertion for free!? Weird 3-body simulation
Doing some 3-body simulations with Mathematica® I noticed that there are cases where you can get into an orbit around a planet with little or little to none $\Delta v$.
When approaching the planet, ...
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6
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0
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142
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How does one "mothball" a spacecraft, and then how does one "un-mothball" it later?
There are various things to do to an automobile if you are going to store it for a few years. Depending on the situation, you might ask a friend to start it once a month, and/or you might pull the ...
- 154k
4
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1
answer
91
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Osiris-REx's trajectory modified to intercept the 2029 Apophis+Earth conjunction? How much delta-v required to hit specific point in space and time?
Ars Technica's June 27, 2025 An exceedingly rare asteroid flyby will happen soon, but NASA may be left on the sidelines includes the following:
NASA has some options for tracking Apophis during its ...
- 154k
2
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1
answer
78
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Is the June 2025 NASA's Office of Inspector General report published somewhere where we can read it?
Ars Technica's June 27, 2025 An exceedingly rare asteroid flyby will happen soon, but NASA may be left on the sidelines includes the following:
But in a report published this week, NASA's Office of ...
- 154k
2
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0
answers
41
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Coefficients for geopotential model
I would like to implement a spherical harmonic geopotential model into python, to find the force on an object (probably using EGM2008 or JGM-3), does anyone know where I can find a data set with all ...
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3
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0
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54
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Finite burns and non-native forces in GMAT python api
I am trying to use GMAT to simulate a satellite with a long conducting tether experiencing lorentz drag as it passed through the Earth's magnetic field. For this purpose, I have set up the Python API ...
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157
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Are there any efforts towards producing 148-Gd as an alternative to 238-Pu for RTGs?
After 05:16 in Real Engineering's March 22, 2025 video NASA'S Plutonium Problem there's a discussion of how the various radioisotope options for Radioisotope Thermoelectric Generators (RTGs) was ...
- 154k
12
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1
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2k
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What encryption scheme was used for the Columbia shuttle from-ground commands?
I'm a security enthusiast(not a professional) so
commands to the orbiter from the ground were routinely encrypted
gets me wondering 'how'. STS-107 was in February 2003 while to day rock solid ...
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3
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0
answers
121
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How much extra RP-1 fuel does the second stage of a SpaceX Falcon 9 rocket carry with it?
How much extra RP-1 (fancier name for kerosene) fuel does the second stage of a SpaceX Falcon 9 rocket carry with it? Is it the same for every space flight or does it vary from one mission to another? ...
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2
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1
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219
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Where to find a list of all the individual payloads intended to be deployed by (crazy-looking) SpaceX Transporter-14?
The image below is from this SpaceX tweet about the Transporter-14 mission, launched from Vandenberg in a polar orbit, which I learned about from Wired's June 23, 2025 Scientists Are Sending Cannabis ...
- 154k
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97
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If the airplane had not been invented could orbital flight have been achieved so quickly in the 20th century? [closed]
Was the development of the airfoil on an airplane essential for there to be only thirty-one years between Robert Goddard's first flight of a liquid-fueled rocket and the launch of Sputnik? Could the ...
- 7,279
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123
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Robots kicking away debris
I just read a new sci-fi book by someone working at ESA. It delves into a lot of topics: orbital warfare, satcom, lunar colony, nuclear explosion in orbit. But, there is also a chapter where ...
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2
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A Dawn Mk-ll Aurora spaceplane launches a satellite, can it reach GEO/LEO on it’s own?
The Dawn Mk-ll Aurora spaceplane can reach ~20km height, can a 10kg artificial satellite launched from it continue its way to GEO using its own propulsion system after being separated from the ...
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1
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174
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What would scientists do with 5 minutes in person on Mars? [closed]
Are there any quick things that, right now, explorers of Mars are frustrated that they can't do remotely that they wish they could just be there for 5 minutes to do manually?
I mean, if scientists had ...
- 1,737
3
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0
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101
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Some examples of an "increasing number of defunct satellites zip(ping) around in space, producing all kinds of weird bleeps and bloops"?
Gizmodo's June 24, 2025 NASA Satellite That’s Been Dead for 57 Years Sends Mysterious Signal to Earth describes an interesting event.
A radio transient event was detected by fast signal processing at ...
- 154k
4
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1
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448
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How did the ISRO's Chandrayaan - 1 impacter get enough Delta V to separate from the orbiter and impact the moon?
The Chandrayaan - 1 was launched by the ISRO on 22 October 2008 and reached the final selinocenteric orbit on 12 November 2008.
Its final circular orbit was at an altitude of 100 km. How did the ...
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49
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Hybrid combustion of ALICE with LOX?
I'm working on a sci-fi universe for a role-playing game and am wondering if a disposable short-distance rocket (most likely used in a cheap missile) could be optimized by adding liquid oxygen to the ...
4
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2
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332
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Is the mean motion measured for the generation of TLEs?
I know that before generating TLEs with SGP4, there has to be a measurement of some points. What exactly gets measured in these points? Is it the mean motion or the semimajor axis? How is the ...
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419
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Valid results? Hohmann analog with gravity assist
Consider three circular and coplanar orbits. For a transfer between the inner to the outer orbit, igniting only two impulses, it is known that a Hohmann-transfer is the optimal maneuver.
Performing a ...
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2
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2k
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How many rockets have been re-engined?
I got curious about the idea from the recent Raptor-EUS question and am wondering now how many rockets, particularly launch vehicles and upper stages for orbital vehicles, have been re-engined?
The ...
- 17.7k
3
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158
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Can anyone with a big enough antenna reprogram deep space spacecraft?
I was recently reading about how Voyager 2 has had several remote software updates performed during its lifetime. This got me thinking - could anyone with a powerful enough antenna reprogram Voyager 2 ...
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125
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What is the current status of the Wingless Electromagnetic Air Vehicle (WEAV)
From https://en.wikipedia.org/wiki/Wingless_Electromagnetic_Air_Vehicle :
The Wingless Electromagnetic Air Vehicle (WEAV) is a heavier than air
flight system developed at the University of Florida, ...
- 34.1k
16
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3
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1k
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How much thrust could radiators provide?
Usually heat is a waste - spacecraft use substantial mass to get rid of it via radiators.
But what if one uses it for thrust? Why not to make some dumb photonic engine out of it?
Obviously it would be ...
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128
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Is there really no plan for whether to tell the crew about an impending loss of crew?
I was reading Wayne Hale's blog about the Colombia disaster. This passage speaks the possibility of informing the crew about their fate, if it had been possible to inform them (or, depending who you ...
- 1,064
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74
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How are Stewart platforms used to simulate spacecraft docking or support ground-based testing?
I'm an undergraduate student in Electrical and Electronics Engineering, and I'm exploring the use of a Stewart platform (6-DOF parallel manipulator) for applications in spacecraft docking simulation ...
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1
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2k
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Is there ever any reason for a satellite to point its thrusters and burn towards or away from earth?
I encountered this question:
What is the fate of Krypton exhaust from Starlink thrusters?
Where a commenter points out that the exhaust velocity of krypton on the Starlink ion thrusters is above earth ...
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145
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Has there ever been a plan for a 2nd mission to rescue a first non-crewed mission?
New edit according to @uhoh 's advice:
There have been efforts to recover uncrewed spacecraft using radio commands, but a 2nd mission with a new spacecraft... ever?
Old:
What specific assets or data ...
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236
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What is the fate of Krypton exhaust from Starlink thrusters?
The chemical composition of the atmosphere is stratified by molecular weight. Above 1000 km it is dominated by He and H2 with single digit molecular weights.
Below LEO it is dominated by N2, O2 and ...
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