All Questions
18,620
questions
23
votes
3
answers
4k
views
Was Starship’s “launch window” administrative, rather than due to orbital mechanics?
According to Wikipedia,
a launch window is the time period on a given day during which a
particular rocket must be launched in order to reach its intended
target.
SpaceX’s internet launch coverage ...
- 18k
6
votes
1
answer
2k
views
Did Starship Ship 25 burn up on re-entry?
SpaceX Starship Ship 25 launched and managed a successful separation from the booster and reportedly made it into space before the autonomous flight termination system activated, destroying the ...
- 744
2
votes
3
answers
191
views
Disposing of Obsolete Satellites by Propelling to the Sun
I'm not scientifically adept, so bear with me. Would it be feasible to retain enough fuel on new satellites/space stations, etc., that we could dispose of them when obsolete by sending them to the ...
Jim Elmore
3
votes
0
answers
92
views
How much lead (kg) would you need to survive for an extended period of time in Jupiter’s radiation belts?
Imagine you have a 1 by 1 by 2 meter chamber that a human needs to survive in for one year, while orbiting in Jupiter’s radiation belts. How much lead, in weight, would have to surround the chamber to ...
- 31
2
votes
3
answers
798
views
(How) would the water deluge system impact Starship superheavy captures?
(How) would the water deluge system impact Starship superheavy captures, when they eventually manage to return to starbase?
Could it be turned on during landing attempts? Would that reduce lift (...
4
votes
2
answers
231
views
Does swimming experience help to adapt to weightlessness?
In the story I currently write, I have a character who has been a passionate swimmer for decades. Now, she goes to space. I wonder how she would adapt to weightlessness, and would her swimming ...
2
votes
0
answers
36
views
Nozzle contour estimation (Merlin 1D Vacuum)
I would like to run a fluid simulation of the diverging section of a Merlin 1D Vacuum engine. While most relevant parameters (such as expansion ratio, flow rate, and nozzle area) are readily available,...
- 149
2
votes
1
answer
113
views
How does SpaceX get its boosters from the ASDS to SLC-40?
Getting a freshly-landed booster from a drone ship to pad 39A seems straightforward: there's a deepwater channel from Port Canaveral to a dock next to the VAB. Sail the ASDS up, lift the booster off ...
- 14.6k
4
votes
2
answers
460
views
Are rockets deliberately throttled back towards the end of the burn to spare crew and airframe g-forces?
Throughout its burn, a rocket gets lighter as propellant is consumed. As a result, acceleration (and g-force) increase. In the shuttle, the SSMEs were throttled back towards the end of the burn ...
- 18k
0
votes
0
answers
88
views
Can coking be avoided by pumping fuel after shutdown?
As I understand it, coking in kerolox engines occurs when the engine shuts down and fuel flow stops, causing fuel still in the coolant channels to overheat and decompose.
Can this problem.be avoided ...
- 2,645
1
vote
0
answers
31
views
Definition of "elevation mask" when it comes to sensors and ground stations?
My understanding is that elevation mask is a term for purposely limiting sensor observations, usually on the ground, by intentionally blocking sky observations from the horizon to a specific elevation....
- 21
2
votes
1
answer
175
views
On space stations, what do they do with small solid particles which are free floating?
I heard a claim that a piece of graphite, of half a millimeter size which broke from a pencil can kill a person who inhales it. Is this a major problem or an exaggeration? In a gravitational ...
- 3,117
4
votes
0
answers
87
views
Do ISS astronauts have a preference for when EVA tasks are scheduled with respect to lighting conditions?
Given the choice, do ISS astronauts prefer to schedule EVA tasks on the “day light” side of the ISS, the “shadow" side of the ISS or in the shadow of Earth’s night side?
I suspect the intense, ...
- 18k
3
votes
0
answers
71
views
Have spherical dish antennae been used with Molniya satellites to avoid switch-over signal loss?
Molniya-orbit communication satellites work well for ground locations near the poles. These high eccentricity, highly inclined orbits, with a period of 12 hours, “loiter” for about 6 hours over the ...
- 18k
9
votes
2
answers
3k
views
Term for deformation due to gravity
In this video,
If you look closely, you can see the smaller planet deforming before the actual collision. I think I remember a term existed for this. I think it is ...
- 99
3
votes
1
answer
138
views
Could mirrors used in a Dyson Swarm be made from asteroids in the inner asteroid belt?
In this video from Kurzgesagt they said that one would need to disassemble a whole planet to build a Dyson swarm around the sun.
The video went on about mining Mercury and using the materials ...
- 4,710
10
votes
3
answers
3k
views
What is the largest object/mass that can survive entry into the earth's atmosphere from space without heating to 40 degrees C, or above?
This question is of interest because there are terrestrial organisms, such as bacterial and fungal spores, and even complex multicellular organisms, such as tardigrades, which can survive deep space ...
- 111
6
votes
1
answer
253
views
Why use plutonium when sunlight is everywhere? Any proposals to use concentrated solar power instead of Pu238 as a heat source for TGs?
Why use plutonium when sunlight is everywhere? The case for powering thermoelectric generators (TG) with concentrated solar rather than plutonium:
Spacecraft operating in the inner Solar System ...
- 18k
-2
votes
0
answers
80
views
Why doesn't the starship superheavy booster need heat shielding [duplicate]
Why doesn't it need heat shield while the second stage does?
- 51
1
vote
0
answers
61
views
What is the feasibility of High Resolution (< 5m) Hyper spectral Imaging satellite?
Many companies are coming up with claim of less than 5m resolution of hyper spectral imagery, although the payloads of such caliber could be built, I have come to the understanding that SNR would be ...
3
votes
1
answer
209
views
Who is manufacturing the solar panels for Starlink satellites?
I am trying to understand the supply chain behind the Starlink Satellite Constellation. I am wondering how SpaceX is able to source those many solar panels. If somebody could give a brief explanation, ...
11
votes
5
answers
1k
views
In circle orbit, give a delta V to a satellite, how to find final orbit altitude?
I think this is a very very simple question for me, but unfortunately I cant solve it...
A satellite is orbiting in a circular path at an altitude of 600
kilometers. If the satellite is capable of ...
- 157
1
vote
0
answers
85
views
Aspiring to Build a Space Rover from Scratch – Where to Begin? [closed]
What fundamental concepts, beginner-friendly resources, or online courses would you recommend for someone starting with little to no background in robotics?
At first,
I want to build a an autonomous ...
3
votes
2
answers
312
views
If a baby was born on the ISS, what would its nationality be?
If a baby was born on the ISS, what would its nationality be? Many countries grant citizenship to any baby born within their territory, but the ISS is not national territory ... or is it? If a ...
5
votes
2
answers
469
views
What does a "handover" really mean in satellite communications?
I am working on simulating a satellite constellation and I keep coming across the term "handover". My general understanding is that a handover is when a ground station switches its connected ...
1
vote
0
answers
100
views
Are smaller rockets easier to land? [closed]
Is it easier to land a smaller rocket compared to bigger rockets?? Since they are lighter
- 51
10
votes
1
answer
2k
views
How is hot staging of Starship expected to provide such a large (10%) increase in total mass to LEO?
there's a meaningful payload to orbit advantage with hot staging that is conservatively about a 10% increase
(Elon Musk during Twitter Spaces interview on June 24th, 2023, timestamp 37:13)
In a line ...
- 6,418
1
vote
0
answers
72
views
Single shaft turbopump vs two turbopumps
What are the pros and cons of using same turbopump for fuel and oxidizer and using 2 different pumps for both?
- 51
2
votes
2
answers
1k
views
Is there an anomalous variation of distance between Earth-Moon during a lunar eclipse?
Apart from normal (expected) variation of distance between Earth and Moon in any given time interval, what happens during a lunar eclipse by way of some unexpected (anomalous) deviation? Have lunar ...
- 87
3
votes
0
answers
49
views
Why did the Apollo 16 crew wait until Station 8 to sample ray material from South Ray (instead of earlier during EVA 2)?
During EVA 2 on Apollo 16, the crew planned to sample material from an ejecta ray from South Ray crater at Station 8. Earlier during that EVA, the mission plan had them drive through a continuation of ...
- 887
32
votes
1
answer
4k
views
Apollo 13's plutonium RTG re-entry into the Tonga Trench: Good shootin' or good luck?
Plutonium powered RTGs are encased to survive re-entry. According to the Wikipedia article on Apollo 13
RTGs were used to power … the scientific experiments left
on the Moon by the crews of Apollo …...
- 18k
8
votes
1
answer
127
views
Understanding and breaking down pointing requirements
“< 1 deg, 3σ total angle pointing stability” - What does the 3sigma indicate? Does this mean that 99.7% of the total pointing error (which I assume is computed via a sim), is within 1 deg? If it ...
14
votes
2
answers
1k
views
Does the atmospheric pressure of Mars fluctuate because of the seasonal evaporation of the polar ice caps?
The carbon dioxide ice on the Martian poles are known to evaporate every summer and re-deposit every winter.
Where does this carbon dioxide 'go' and does it mean there is a seasonal variation in the ...
- 341
3
votes
1
answer
96
views
Which SPICE kernels I have to load to calculate state vector of the outer planets
I'm developing a software to show the planets in the sky. I have loaded the following kernels:
...
- 131
20
votes
3
answers
5k
views
Why do the boot prints on the moon appear bright in some photographs or film?
I've seen that in some videos or photos of the moon mission, the boot prints appear brighter relative to the untouched ground:
But in some other cases, they are the same brightness as the ground:
Is ...
- 565
20
votes
1
answer
3k
views
Why are the Martian poles not covered by dust?
The Martian surface is known to have periodic 'dust storms'.
Depictions of Mars typically show poles with ice at the surface. If that is the case why are the Martian poles not blanketed with a thick ...
- 341
1
vote
0
answers
108
views
Does an overexpanded nozzle behave like a suction cup?
It is generally said that, to obtain optimal specific impulse, a nozzle should be just the right size that the exhaust pressure is equal to the ambient pressure. Quoting this answer, a relevant ...
- 482
0
votes
2
answers
160
views
Which satellite is this very bright object? - part 2
A few weeks ago, I asked the same question about a bright object that I observed, initially thinking it wasn't Venus, but was told that it actually was Venus. Oops, fair enough. Here's another bright ...
- 119
1
vote
0
answers
69
views
How to maintain minimum distance between satellites for duration of their orbits
I am working on a simulation in python that involves propagating hundreds of satellites over time. For simplicity, let's assume I have satellites at only a single inclination separated into multiple ...
2
votes
2
answers
114
views
What is the prevalence of nitrogen, phosphorus, and potassium in the asteroid belt and in comets?
As someone with a light background in controlled-environment agriculture, I'm familiar with the importance and use of N/P/K in growing useful plants. This got me thinking about how common these ...
- 315
12
votes
3
answers
5k
views
Why does the Curiosity rover camera image resolution have "milliradians" as a unit?
NASA's published specs for the Curiosity rover cameras says that the image resolution is in milliradians per pixel. Which is odd because image resolution is measured in physical size units, i.e. ...
- 565
4
votes
0
answers
57
views
What document describes the scientific benefits of the LRV through an increase in the diversity of rocks returned by Apollo 15-17?
Logically, it makes sense that the rock samples returned by the Apollo 15-17 missions tend to be more diverse than the ones returned by previous missions. The astronauts could reach regions of ...
- 887
6
votes
0
answers
149
views
Why did Voyager not use error correction coding for uplink?
Error correction coding was used for downlinked Voyager data, but why not for the uplink direction (if I'm correct in thinking it wasn't)? According to Edelson et al. 1979 "Voyager ...
- 381
2
votes
0
answers
96
views
Is there any data for space debris that I can use to develop an AI model to predict the orbital decay time?
I need to develop a model to predict the orbital decay time for my graduation project but I searched for data that can help in that project and I failed to obtain such data.
Can any one suggest a ...
4
votes
0
answers
102
views
Mass Breakdown of Apollo CSM by Subsystems? (also Cost Breakdown)
I am looking for a mass breakdown of the Apollo Command and Service Module by subsystems, like this Lunar Module's chart from the NASA publication After LM. I am particularly interested in how much of ...
- 101
3
votes
0
answers
54
views
Modeling Spacecraft Jitter from Reaction Wheel Imbalances
I am working on a project trying to model a satellite's pointing error caused by jitter from the reaction wheels. I have found a couple of papers (Paper 1 and Paper 2) which implement the simple model ...
- 73
3
votes
3
answers
529
views
How do you design a spacecraft with a spinning section for "artificial gravity"?
Science fiction spacecraft sometimes have a section that spins to provide "artificial gravity" through centrifugal forces. I'm thinking in particular of the Discovery spacecraft from the ...
- 995
0
votes
0
answers
45
views
Methane vs propane as rocket fuel [duplicate]
How would propane compare with methane as rocket fuel?
Propane can also be stored as liquid under pressure.
- 51
-4
votes
2
answers
201
views
Why does centrifugal force cause gravity?
I have read several space books on processing resources in space. They talk about using distillation by rotating a section. WOuldn’t the centrifugal force cause the mixture to separate by its self? ...
- 81
0
votes
0
answers
45
views
How can I get the CAD model and dimensions for the connector support of a space launcher?
I am a university student and want to do topology optimisation and additive manufacturing research for this component but cannot seem to find the accurate dimensions for it. I would be glad if anyone ...
- 1