All Questions

1
vote
0answers
16 views

Hohmann transfer trajectory and “porkchop plot”

The “porkchop plot” for a spacecraft flying from Earth to Mars would show contours of equal characteristic energy against combinations of launch date and arrival date. Assuming the spacecraft has ...
1
vote
1answer
22 views

Could Hubble observe the night side of the Moon?

IIUC the Hubble space telescope cannot observe the Sun lit side of the Moon. And Hubble is never pointed closer than 90 degrees towards the Sun. But this still allows for observing the night side of ...
0
votes
0answers
7 views

how to get true anomaly using subsatellite point (latitude)

I am working on an application which is using an orbit propagator. I have a satellite which sets its latitude using this orbit propagator. I want to change the latitude of the satellite by a new value,...
7
votes
1answer
55 views

Asteroid impact on the Moon: which effects cause the flash?

It is most likely that there was an impact on the Moon during yesterday's lunar eclipse. I am trying to get some more understanding of this so that I could maybe do a more detailed video on this ...
4
votes
2answers
226 views

How did Lunokhod 1 become lost in 1971; in what ways did astronomers “look for it” after that?

The Smithsonian Magazine article Lost Soviet Reflector Found on the Moon says: There are actually five retroreflectors on the Moon: three placed by Apollo astronauts and two that sit atop Soviet ...
3
votes
1answer
75 views

Is it possible to protect a Cubesat's electronics from 100g of acceleration?

I am currently researching the feasibility of setting up a coilgun that launches Cubesats for a paper. 1 cubesat per launch total payload mass <100kg.
0
votes
1answer
124 views

How much does a swing-by change the orbit of the planet?

A friend of mine told me that one Voyager swing-by moved the orbit of Jupiter a foot closer to the sun. I understand that Jupiter was slowed by the gravity assist, but I figured it would be minuscule ...
0
votes
1answer
42 views

Help with my tensor tension; how to derive and calculate this rigid body gravity gradient torque?

Tensors make me tense. Imagine a long thin rod in a circular orbit. The gravity gradient will produce a net torque on the rod whenever it is not oriented parallel, or perpendicular to the radius ...
1
vote
1answer
47 views

What psychiatric and psychological tests do people need to pass to become astronauts?

I am writing a short film about an astronaut during re-entry to earth. Part of the conflict I wrote is that the astronaut could not pass the mental tests required. Could anyone tell me any tests ...
3
votes
2answers
78 views

How would you move in low gravity without a suit?

Assuming your in a habitable environment, how would you move on a planet or moon with significantly less gravity without the encumbering EVA suit?
1
vote
1answer
49 views

Why did the S5.2/9D21 rocket engine engine have pyrocharges?

In a recent question, an answer showed a diagram of a Soviet S5.2/9D21 rocket engine. According to the diagram, there are four pyrocharges (3, 7, 24, and 27) in the engine. What is the purpose/...
1
vote
1answer
94 views

Who were the major manufacturers of the Apollo 11 rocket — STILL ALIVE?

Organizing an exhibition around photographs from the 1969 launch and wanted to invite manufacturers.
1
vote
1answer
64 views

What are the limitations of monopropellant RCS thrusters in a re-useable spacecraft?

I understand the disadvantage of monopropellant is mainly dependent on the life of the catalyst. There is a possibility of catalyst failure due to it being subjected to catalytic poison and catalytic ...
1
vote
1answer
48 views

Was there once a semi-serious space-art project planning to use solar reflectors to put a spot of light on the crescent Moon?

Reading the question What are the effects of orbital reflectors and advertising on scientific observation and orbital debris? I am reminded of a story I read a while ago about an even in the past, ...
4
votes
0answers
59 views

What are the effects of orbital reflectors and advertising on scientific observation?

There's a couple of startups and initiatives which are proposing "space billboards" which have been getting a lot of bad press recently. Most of the proposals involve a bunch of cubesats with large ...
4
votes
0answers
59 views

Falcon 9 2nd stage pusher; how far does it continue to extend as it accelerates separation?

I've just watched Scott Manley's video SpaceX's Water Landing Reveals Rocket "Secrets" (or, What We Learned from CRS-16) (again) and he mentions the second stage "pusher" in the center of the view (...
3
votes
1answer
91 views

Help with Scott Manley's rigid body dynamics narration

I've just watched Scott Manley's video SpaceX's Water Landing Reveals Rocket "Secrets" (or, What We Learned from CRS-16) (again) and there's some rigid body dynamics in there where I'm not sure I am ...
3
votes
0answers
32 views

Cost of an earth observation cubesat satellite like Planet-s Doves?

With the Cubesat standard and more and more components being available off the shelf, this should really bring down the price of building a (simple) earth observation platform. I am curious how low a ...
10
votes
1answer
138 views

How will SpaceX Starship deploy its payload?

Most modern orbital launchers like the SpaceX Falcon9 have their payload at the front covered by a fairing which splits in half, ejecting the fairings and exposing the payload for deployment. With ...
1
vote
0answers
64 views

What is wrong with my orbit sim equations? How can I fix them?

Edit: Partial question: The object now moves in an ellipse like it's supposed to, but it orbits around a different point than I intend. How can I make it orbit around a particular object at a point? ...
1
vote
0answers
39 views

What causes these plume features on Delta IV Heavy?

Just catching up on the Jan 19th launch of NROL-71 on board the Delta IV Heavy and I noticed these very prominent features in the exhaust plumes, beginning around the time the centre core is throttled ...
3
votes
1answer
47 views

Luna artificial satellite eclipses

Have we been able to see the shadow on the Moon's surface of any artificial satellites that orbit the Moon?
-2
votes
2answers
92 views

Why didn’t the astronauts on the moon ever get out of breath? Even while running, or falling down?

My question is, even with the demand of learning how to walk and all the falls and and bumbling around of the astronauts, they never ran outta breath? Maybe in the newer missions they caught this and ...
5
votes
0answers
39 views

Does NASA still plan for the Mars Ascent Vehicle to burn wax from the surface to orbit?

The NASA news item From Pedicures to the Peregrine Rocket, Paraffin Wax Proves Its Worth says: The paraffin-based fuel also works under challenging environmental conditions, like the very low ...
0
votes
0answers
10 views

Has direct bandgap photoemission from III-V solar panels on spacecraft ever been detected or reported?

I thought I had asked this question before, but I can't find it now so I will ask here. I have asked a related question in Physics SE: Do III-V based photovoltaics “glow” (photo-luminesce) when ...
4
votes
1answer
66 views

Launch window for the Apollo Lunar Module?

If something would have gone wrong after a successful Moon landing requiring to ascent as soon as possible, what about the launch window for the lunar rendezvous maneuver? Could they ascent at any ...
15
votes
3answers
4k views

Why was the engine of the launch vehicle recently tested in Iran “not a very good missile engine”?

The NPR News item What's Iran Up To With Recent Rocket Launch Attempt? by NPR's Geoff Brumfiel, about a recent launch test in Iran includes the following: Earlier this week, Iran attempted to ...
18
votes
6answers
8k views

Why can't they just drop a solar winch down from a shuttle and have planes fly up and clip things on?

Why can't they just drop a solar winch down from a shuttle and have planes fly up and clip things on? I know of the idea to have a space lift but the cable necessary is too expensive. Why can't we ...
5
votes
3answers
272 views

Has any man-made satellite or space vehicle ever been hit by a natural meteoroid?

For precision I'm excluding artificial meteoroids and satellite debris (which is discussed in another question) of all kinds. I'm also considering collisions large enough to produce a noticeable ...
0
votes
0answers
29 views

Why does Delta IV have a programmed hold at T-4 minutes? [duplicate]

Why is this hold a planned part of the launch sequence? Can the delay at this point vary to allow for better launch conditions (eg weather, range obstruction)?
2
votes
1answer
78 views

What determines rocket height/width?

I was wondering what determines the height/width ratio of a rocket? What are factors that influence the choice between a tall skinny rocket like Falcon 9 or a wider shorter (in ratio) like Ariane 5 or ...
4
votes
1answer
68 views

Distribution of satellites by inclination

What is the distribution of Earth orbiting satellites by inclination? In other words, what inclinations are more or less popular? I work with Earth observation myself, where many satellites are Sun-...
0
votes
0answers
29 views

Would there be value in taking tardigrades on a Lunar mission?

China's Chang'e 4 mission recently initiated biological experiments on our moon. There's value in performing those experiments, of course. Now, I'd be curious to see how tardigrades do in the long ...
3
votes
1answer
39 views

How can one know that Chang'e-4 was in “locked to the Queqiao” from this SDR spectrogram?

Deep space SDR enthusiast and amateur radio operator Edgar Kaiser @df2mz's 28-Dec-2018 tweet says: Chang'e 4 in lunar orbit last night on 8479.77 MHz. The spacecraft seems to be locked to the ...
1
vote
1answer
35 views

What lateral and rotational accelerations can a spacecraft achieve?

I've found information like the Space Shuttle Orbiter has so many thrusters each generating so much force to maneuver "with redundancy" in orbit. But without knowing something like how many thrusters ...
1
vote
1answer
71 views

How close did Apollo 16 astronaut Charles M. Duke Jr. get to the edge of Plum crater?

The New York Times article What Happened to Earth’s Ancient Craters? Scientists Seek Clues on the Moon’s Pocked Surface includes a NASA photo with the caption: Astronaut Charles M. Duke Jr., of the ...
2
votes
0answers
32 views

Is software available for writing two line element files from keplarian elements?

I am interested in writing a TLE file from existing Keplerian elements. Is software available on the web to do this?
1
vote
1answer
118 views

Why not turn off the main engines while using the launch escape system on liquid fuelled engines?

I've seen a couple of launch escape systems firing and the rockets main engines are on, isn't it more safe if you turn off the engines? Edit: i agree that the engines turning off might be not so ...
2
votes
1answer
99 views

Active liquid cooling for heat shield

I have not been able to find much that has been written about active liquid cooling for heat shields using cryogenic fuel. It seems it has been mentioned but not really researched in depth. It's my ...
15
votes
4answers
5k views

Are there any known reasons why there are no spaceports in the European Union?

As far as I know, there are no spaceports in the European Union. Why is it so?
0
votes
0answers
32 views

Changes in rocket engine design, based on fuel being used [on hold]

What are the major differences in rocket engine design for different fuel combinations such as H2L+ LOX or Solid fuel or RP-1 + LOX ETC...
1
vote
1answer
169 views

How much fuel would the Starship need to LAND 100,000kg on Earth?

The SpaceX's Starship is in orbit, empty payload. Magically, 100,000kg of payload appears inside the ship, setting aside all the logistical questions of how it got there. Now it needs to deorbit and ...
2
votes
0answers
40 views
+100

Computing the local orbital frame vector directions and angles of gyroscope direction in the satellite

In the context of the study of a cubesat (little satellite), I am asked to define the local orbital frame and compute the local orbital frame vector directions as a function of time (...
6
votes
1answer
96 views

How to manage exploration of unlandable asteroids? [on hold]

If rotation period provides greater centrifugal force than gravity, having tangential surface velocity greater than escape velocity. How would one probe manage to hook to one of them, in order to ...
4
votes
1answer
111 views

Chang'e- 4 safeguards to biological Contamination on the moon?

What kinds of safeguards does Chang'e 4, China's lander on the dark side of the moon use, in order to prevent biological contamination on the moon? How well are they documented?
5
votes
1answer
538 views

Would any manned orbital launches to date have been possible (but lower) if they were launched retrograde instead of prograde?

Manned launches have always been launched prograde to take advantage of the Earth's rotation velocity boost, and often in order to match the prograde orbit of another spacecraft for rendez-vous. I ...
0
votes
1answer
100 views

Constant Acceleration in Space. How much time for a given distance?

I have been researching a lot and can't make any sense of it all, so I am trying my luck here. I want to program a simple formula that gives me the travel time in space. I have a constant thrust of ...
0
votes
0answers
6 views

How stable is our universe? [migrated]

I've been reading and thinking about this subject for some time but i can't seem to find a clear answer. after reading : Aspects of the Higgs boson suggest that our universe is only “marginally ...
-1
votes
1answer
69 views

What are the percentages of matter in the universe, and how did we find out? [closed]

What are the percentages of matter in the universe? And how did we find out about it?
2
votes
1answer
53 views

Were there fruit fly or silkworm eggs in the biosphere of the Chang'e 4 lander?

Drosophila melanogaster or bombyx mori? 29 700 google hits for chang'e silkworm 27 500 chang'e drosophila 25 100 chang'e "fruit fly" https://de.wikipedia.org/...

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