All Questions
18,478
questions
6
votes
1
answer
185
views
How do engineers measure satellite drag, and how do they track it over time?
I’ve been slowly getting myself familiar with astrodynamics and understanding satellite orbits. I’m familiarizing myself with the concept of drag experienced by the satellites. I am curious about how ...
- 277
0
votes
0
answers
74
views
How to compute the pointing accuracy
I was wondering if there's an equation or somewhat intuitive way of computing the pointing accuracy of a satellite?
What parameters do I need and how would I go about it?
- 1
12
votes
3
answers
3k
views
Would electrically powered thrusters on JWST have made it last for decades longer?
Since the lifespan of the James Webb Space Telescope is determined by the amount of fuel it can carry for its thrusters, used to decelerate the reaction wheels used to orient the telescope, and since ...
5
votes
1
answer
172
views
Given historical TLE’s, how do I determine the path/orbit/LLA of a satellite for a given historical period?
Im trying to get the historical Lon/Lat/Alt of a starlink satellite. I'm using TLE's from space-track and Skyfield to calculate latitude, longitude and altitude of satellites for a given date range. ...
- 277
2
votes
0
answers
57
views
EPS sizing for lunar mission
As part of a university project, I am working on EPS sizing for a mission to the lunar environment. I have sized the SA and batteries, chosen the components and the PDCU; however, having never been in ...
- 29
3
votes
0
answers
186
views
Why do ~GEO sats seem to cluster around the top portion and bottom portion of the belt, 180 degrees apart?
I made a 3D tle model from https://www.space-track.org/ API. I drew a dashed blue line to show the really "geo" orbits that hardly move with time (ECEF). Then there are a bunch of sats that ...
- 31
1
vote
1
answer
123
views
How can I get a list of GNSS satellites in view for a given date/time
I need to generate a list of which satellites were in view at a given date/time. I'm specifically interested in the Galileo constellation of GNSS satellites, and I'd like to get a list of when each ...
- 113
4
votes
1
answer
204
views
Why did SpaceX change Falcon 9’s engine configuration?
Why did the Falcon 9 go from a 3x3 configuration to a ring of 8 around a central engine? Was there some sort of aerodynamical advantage to be found or something?
https://en.wikipedia.org/wiki/...
2
votes
1
answer
146
views
Selfie from space with AWS Groundstation
I hope this question fits this community!
While browsing r/AWS today I read about someone who was able to make a "space selfie" with AWS Groundstation:
The progress is detailed further down ...
- 1,158
0
votes
0
answers
62
views
How to "turn off" ADCS system to monitor orientation after firing MDT's?
I've been tasked in a hypothetical mission of determining if an Attitude Determination and Control System (ADACS) can be "turned off" during MEMS Digital Thruster (MDT) firings so that the ...
4
votes
2
answers
159
views
How could a spacecraft reduce an orbital insertion burn after a Hohmann transfer using gravity assists?
I want to calculate a mission to Saturn, and my theoretical spacecraft has a total Delta-V of about 10,000 m/s. I have seen using different tools that it will take about 6000 m/s for the initial ...
- 115
3
votes
1
answer
436
views
How does the current or future network latency of SpaceX Starlink compare to wired internet?
When reading about SpaceX Starlink, high frequency stock traders are mentioned as a potentially lucrative customers, this is because satellite to satellite communications don't have glass between them ...
- 479
6
votes
0
answers
233
views
How do spacecraft protect their engines from micrometeroids?
A meteoroid impact on an engine bell can easily rupture a coolant pipe. Or it can create an imperfection in the backing plate from where cracks can form. Or it can destroy an injector. All of these ...
- 2,615
1
vote
2
answers
149
views
Deep space mission propellant
For an interplanetary mission that has a duration of 40 years cam we use hydrogen peroxide monopropellants? Can we use arcjets?
- 11
12
votes
1
answer
3k
views
Was there any truth that the Columbia Shuttle Disaster had a contribution from wrong angle of entry?
The principal of my tiny school in Japan was presenting to a student to suggest he make a speech on the Space Shuttle's reentry aspects.
He included newspaper articles on the Columbia space disaster.
...
- 221
2
votes
1
answer
157
views
How do I calculate the maximum northern and southern latitude a LEO satellite can image?
How do I calculate the maximum northern and southern latitude a LEO satellite can image? What parameters would I need?
- 21
2
votes
1
answer
90
views
How to model the gravity of Titan in GMAT
I would like to know how to find the gravity file (.cof) for Saturn's moon Titan. Need this to model the gravity field of Titan.
- 53
2
votes
1
answer
135
views
Propellant choices for a Mars landing; tradeoffs between LOX/CH4 and H2O2/RP-1?
What are the tradeoffs between LOX/methane and peroxide/kerosene for a Mars landing mission?
In which ways are each better or worse than the other?
I think the second one would more attractive for ...
- 21
1
vote
0
answers
47
views
Use local acceleration and angular velocity to calculate rotation matrix
Can I ask if there are any python packages that can fuse local acceleration and angular velocity and get rotation matrix?
Thank you!
- 11
0
votes
0
answers
16
views
Receiver location calculation based on Rinex navigation and observation files [duplicate]
I am trying to calculate the location of the GNSS receiver using the data available in the Rinex navigation and observation files. As a first step I am trying to calculate the pseudo range using the ...
- 1
6
votes
1
answer
506
views
Is it possible to open and close ROSAs several times?
During the preliminary phase of designing a REUSABLE lander for the lunar surface from the gateway, the need to necessarily use deployable SAs came up. In addition, because of the descending and ...
- 61
2
votes
1
answer
216
views
Size of sugar rocket to reach space (suborbital)
How much propellant would an ideal single stage sugar rocket with dry mass of 1 kg need to reach the altitude of 100 km in a suborbital flight when launched straight up? Let us assume the specific ...
- 1,403
2
votes
1
answer
126
views
Inflatable tank/balloon use for recovery
Hopefully this idea makes sense.
Basically if you've seen the space-truck (ROOST), you'll get where I'm going with this.
I'm wondering whether an inflatable tank/tank lining could be used to produce ...
- 917
2
votes
1
answer
134
views
Accidents where discarded stages are propelled by vaporized propellant?
Falcon 1 flight 3 failed when propellant vaporized in the detached first stage's engine, causing it to slam into the second stage. Has this happened to any other launch vehicle? Do launch vehicles ...
- 2,615
0
votes
1
answer
90
views
Running and editing GMAT script files from MATLAB
I am trying to run a design optimisation proccess for some orbital parrameters of spacecraft. To do this, I need to be able to edit and run a GMAT script from MATLAB. Is this possible? If so, how ...
- 11
7
votes
5
answers
5k
views
Why doesn’t SpaceX sell Raptor engines commercially?
I have never studied rocket science and am just curious about this.
I would assume one Raptor 2 engine could launch a small rocket to space. I heard they are able to make them for less than a million ...
- 87
1
vote
1
answer
155
views
Where can I find ephemeris data (up to date) for any of LEO satellites?
A bunch of websites have live tracking of satellites, e.g. this one. Where are they getting the satellite ephemerides data for all of the iridium satellites?
- 277
0
votes
0
answers
89
views
How to estimate the fuel required to send 1 kg to lower mars orbit?
Imagine a rocket with a payload of 1 kg. How much liquid fuel would be required to send that 1 kg payload to lower mars orbit. (1 kg is just the payload not the whole dry mass of the rocket) I want ...
- 1
2
votes
1
answer
120
views
Is specific impulse and thrust maximum in vacuum or for exit pressure equals atmospheric pressure?
According to the thrust formulation of a rocket one can show, that maximum thrust is not delivered for pambient= 0 but for pambient=pnozzle_exit since then the momentum term is maximized.
But then I ...
- 29
1
vote
1
answer
204
views
What is the difference between these two Universal Gravitational Constants? [closed]
Can someone please help understand when to use each of these Universal Gravitational Constants.
G = 6.67 x 10-11 N•m2/kg2
G = 6.67 x (10^(–11)) N(m^2) (kg^(2))
compared to
G = 6.67 * 10-11 m3/kg-1s-2
...
5
votes
3
answers
260
views
How obvious would an Earth-like planet be when searching for signs of life in space?
If a planet nearly identical to Earth were orbiting a nearby star, how obvious would it be to us, using our current efforts to search for signs of life? Would it stick out like a sore thumb? Or ...
- 1,584
11
votes
3
answers
2k
views
Could a Nuclear-Thermal turbine keep a winged craft aloft on Titan at 5000m ASL?
It's what it sounds like: Given the output of the NASA nuclear reactor (the one they're going to use for the Artemis program), and the use of an electric-motor-driven turbine system, how feasible is a ...
- 917
1
vote
1
answer
181
views
What is the chance that there is atleast one water molecule in a given volume of space [closed]
If you imagine a single cubic meter, and place it anywhere in space, in any orientation and take any two opposite faces of the imaginary cube, and stretch them to both edges of the universe; what is ...
- 129
12
votes
2
answers
1k
views
Rocket Engine Failure Rate
I am a reciprocating engine machinist and understand that rocket engines are much much more complex. But I am curious why they have such a high failure rate. Even modern rockets are designed to ...
- 150
2
votes
2
answers
218
views
In theory, could this redesign of the launch profile reduce fuel use? [duplicate]
This is a purely theoretical question, because I suspect that trying to build a launch system of this sort would pose its own set of very complex problems.
That said, the Wikipedia page for the ...
- 131
7
votes
2
answers
139
views
Would a laser seismometer work from lunar orbit?
Lasers today have become extremely sensible, they can detect sub-millimeter movements of a surface from a distance. Could this feature be exploited to create a lunar seismometer working from a probe ...
- 191
14
votes
2
answers
1k
views
What is this small white device with LCD and 10 keys on the International Space Station?
I see this device in many places in International Space Station; what is it called and what does it do?
- 243
2
votes
1
answer
162
views
ISS (ZARYA) TLE to Latitude Longitude Conversion
I am trying to take TLE of ISS (ZARYA) and get the latitude longitude and height. I am aware the TLE is in TEME~(True Equator Mean Equinox) frame. This means that the TLE was generated considering the ...
- 2,921
5
votes
1
answer
126
views
"Received power" on NASA's DSN web page
Out of curiosity, the "received power" shown for a spacecraft on NASA's "DSN now" web page 1 - is that at the receiver, or at the antenna?
I'm looking at one of the antennas now ...
- 51
17
votes
2
answers
1k
views
What kind of heating would occur during a suborbital re-entry?
What kinds of peak temperatures would a stage similar in proportions to the Space shuttle with a similar belly-first approach experience when re-entering from a low suborbital trajectory (similar to a ...
- 179
4
votes
1
answer
127
views
Would Li-Ion batteries for a lunar base energy storage system be transported to the base charged or uncharged?
I'm investigating lunar base power systems and energy storage systems (ESS). One option is photovoltaics (PV) and Li-Ion batteries. A large mass of batteries would be required to power the base during ...
- 143
2
votes
1
answer
103
views
How is stage 2 propelling the spacecraft forward? [closed]
A decent response on how the burning process works but how does this glowy burner push the spacecraft
- 29
22
votes
4
answers
4k
views
How do space probes find their way and how much fuel do they use to travel?
How do space probes find their way, for example, to explore dangerous planets like Jupiter or Saturn that have powerful magnetic fields? Do scientists control it from stations in NASA or they have a ...
- 329
6
votes
1
answer
1k
views
What amount of unburned methane was released in the atmosphere during the Starship orbital test abort?
On April 20, 2023, SpaceX attempted an orbital flight of the Starship rocket. The test ended when the Flight Termination System blew up the rocket after it started tumbling out of control.
When the ...
- 5,324
4
votes
1
answer
125
views
What are the safe structural elements of spacecraft that could be used for on-orbit capture?
I know this depends on the general configuration of a spacecraft, but I am hoping to gain some insights. Assuming you have a servicer spacecraft with an abstracted capture mechanism (i.e., end ...
- 43
21
votes
3
answers
5k
views
Why will Starship's 150 ton payload capacity be sufficient to carry 100 people to other planets?
The ISS weighs 450 tons and carries 7 people for three months without resupply.
Starship is supposed to carry 14 times as many people for more than twice the duration with one third the mass.
How?
- 2,615
2
votes
0
answers
74
views
Where exactly are the BE-7 engines on the Blue Origin HLS for Appendix P?
I was reading about the recent selection of Blue Origin for a second Lunar Lander, and a comment on an article caught my eye. Where exactly are any of the engines on the new lander?
Here you can see ...
- 1,329
5
votes
1
answer
320
views
Ariane 6 upper stage schematic showing integration of APU
I've been reading about the Auxiliary Power Unit (APU) on the Ariane 6 upper stage and am looking for a schematic showing how it's integrated into the stage.
From Thermal Control of the Cryogenic ...
- 177k
1
vote
1
answer
104
views
Distance between Sun and Earth using JPL horizons
Using the JPL Horizons app at https://ssd.jpl.nasa.gov/horizons/app.html#/ would someone help to calculate the distance between the Sun and the Earth say 1 May 2023 00:00 UT? I used the following for ...
- 31
0
votes
2
answers
216
views
Orbit prediction for satellites using the Kepler model
I would like to know how to model the motion of satellites in orbit using Keplerian, i.e. develop a simulation model that tracks paths of satellites using Keplerian orbits in Python?
- 11