All Questions

2
votes
1answer
89 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
73 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-...
2
votes
0answers
67 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
56 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 ...
2
votes
1answer
83 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 ...
4
votes
1answer
78 views

Is software available for writing two line element files from Keplerian 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
138 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
145 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?
1
vote
1answer
201 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
57 views

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 (...
8
votes
1answer
190 views

How to manage landing on unlandable asteroids?

If asteroid's rotation period provides greater centrifugal force than gravity, having tangential surface velocity greater than escape velocity, and/or if due to an oddly enough shape, it has no fixed ...
4
votes
1answer
122 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
561 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
109 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
78 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
65 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/...
1
vote
1answer
100 views

LORRI raw images in uncompressed format

I have been solving inverse problems (upsampling) for more than 20 years to improve the resolution of bitmaps image (http://www.resampling.narod.ru). I would like to try my algorithm to improve the ...
1
vote
0answers
58 views

Cryogenic liquid pressurization resulting in overpressurized tank

I want to pressurize a cryogenic liquid (LN2 in this test. Eventually LOX). I have a setup similar to this and follow a similar procedure to what is described, but I don’t see the same tank pressure ...
4
votes
2answers
141 views

What does it mean to ask for a date beyond epoch time?

I am fairly new to this industry. As I am playing around with a library on Python, ephem, I have encountered an error saying that: ...
3
votes
1answer
110 views

Why doesn't the Merlin 1-D use higher LOX to RP-1 mixture ratios?

So I've been screwing around with CEARUN (https://cearun.grc.nasa.gov/), which is the chemical equilibrium with applications program created by NASA. I've been using it to calculate theoretical ISP's ...
3
votes
1answer
111 views

What can cause grooves (stairs like) features on Mars's ground that is opposite to water flow direction?

Looking at an image taken by Mars Odyssey THEMIS (Thermal Emission Imaging System) camera of an unnamed crater in Aonia Terra region I noticed what looks like grooves or ridges that resemble a stair ...
5
votes
2answers
257 views

Left behind photo

After several trips to moon there were several items left behind on the moon's surface, including foot prints. Is there any photo or registry of any of those items taken recently?
5
votes
1answer
190 views

Where is that lunar-grown cotton seed sprout?

Most of us have seen this picture of the cotton seed currently sprouting inside a Chinese lander on the far side of the moon: Source The image shows see a plastic grid with a gelatinous overlay of ...
-1
votes
2answers
124 views

Is rail gun conversion possible? [closed]

can a rail gun be converted into a "High Velocity Pulse Engine",to be used as a "Jump Drive" to achieve light speed capabilities.
2
votes
0answers
42 views

Camera costings for Opportunity/Spirit/Curiosity rovers

I'm currently working on a project investigating the practicalities of a Mars Sample Retrieval rover, as part of my qualification. My area of concern is command/control, and I am struggling to find a ...
1
vote
0answers
34 views

Is it possible to “shape” area impacted by radiation shielding during interstellar travels? [closed]

If I have uderstood radiation/other shielding described in other questions correctly...it will be among other things provided by magnetic field(s) generated by superconductors. Is it possible to ...
15
votes
1answer
4k views

How did humans grow plants on the Moon despite the harsh conditions?

The Chang'e 4 lander contains seeds to grow plants on the Moon. The Moon has non-sustainable life conditions. Among those are the lack of water, atmosphere, the varying extreme temperatures, the low ...
3
votes
1answer
118 views

Could protons in the Sun's solar wind be used to create a photonic laser thruster for a spacecraft?

I have a conceptual idea for a photonic laser thruster for a spacecraft and I am wondering if this particular idea has already been thought of and whether or not it is capable of generating enough ...
35
votes
4answers
13k views

Why did the Chinese send flies and plants to the far side of the moon?

The Chinese space craft that just landed on the moon had a tube with a biosphere in with flies and plants. What are they expecting to learn? Didn't we already experiment that on the ISS? Source ...
6
votes
4answers
192 views

During a government shutdown, is it possible for US rocket companies to launch from outside the US?

With the ongoing shutdown, it's causing some test flights of SpaceX and others to be pushed back. If it goes on for an extended period, is it possible for said rocket company to launch from another ...
1
vote
0answers
91 views

Backwards time dilation paradox [closed]

We have a pair of atomic clocks. Let's call them clock A and clock B. We switch both of them on at the same time. Clock A will stay on Earth and clock B will go with the astronauts. Astronauts with ...
21
votes
2answers
10k views

Could colonizing Moon dangerously affect its gravity?

If we colonized Moon it would mean we are moving matter from Earth to Moon. Since Moon is much smaller than Earth could these changes somehow affect its trajectory/movement to the point we could ...
24
votes
4answers
7k views

Why no recent information about or photos of Ultima Thule?

It's been two weeks since New Horizons flew past Ultima Thule but the most recent news on the Johns Hopkins site is dated the fourth of January The image gallery has had no new pictures since the ...
-1
votes
2answers
592 views

Does SpaceX plan to enhance/change the genome of space colonists to speed up the adaptation process to the living conditions on Mars? [closed]

My understanding of biology is that all living organisms adapt to the environment around them. I would even say the environment shapes the very essence of an organism. Gravity alone is a huge factor ...
3
votes
2answers
74 views

How is gimbal angle calculated?

When a rocket is knocked its intended flight course by wind, how is the gimbal angle calculated to return the rocket to its courses? Like, if the rocket intended course is 90 degrees straight off, and ...
3
votes
1answer
157 views

Time dilation between Mars and Earth due to different mass

I am not sure I understand the Time dilation correctly but if mass has dirrect impact on time...than lets consider cosmological event - one orbit of planet Earth around Sun. This event will person on ...
5
votes
1answer
469 views

Rotating in orbit?

Reading this question (Is the cupola, on the inside of the ISS, cold or warm to the touch?) prompted me to wonder about an object in orbit's orientation as it orbits its host object. For example, ...
2
votes
1answer
59 views

NAIF and SpiceyPy returning seemingly inaccurate results

I am yet another amateur astrophysics enthusiast creating a solar system simulator. I began by hard-coding planetary bodies and their satellite orbiting characteristics via JPL data tables such as ...
5
votes
1answer
202 views

What precisely was the character of the non-gravitational acceleration of Oumuamua?

When exactly did Oumuamua accelerate, when did it begin, when did it end, was it uniform across that period, and at what vector did it occur? I've seen some vague references to it lasting 100 days, ...
4
votes
3answers
180 views

If specific impulse is directly related to exhaust velocity, would a ion post-accelerator improve the Isp of a propulsion system?

I understand that ion- and hall thrusters resemble a particle accelerator, and that led me to wonder if a post-accelerator (particle accelerator) used to boost the velocity of the ions would improve ...
21
votes
2answers
385 views

Is the cupola, on the inside of the ISS, cold or warm to the touch?

Does the temperature of the surface of the cupola vary when the ISS is in Earth's shadow, compared to when it is on day side of the Earth? Is it cold to the touch when the ISS in the shadow?
7
votes
1answer
213 views

Why did Apollo have a crew of 3?

Why did Apollo have a crew of three when only two actually reached the surface of the moon? I can see it makes sense for the Lunar Module only to seat two astronauts. Less mass to land softly on the ...
2
votes
1answer
151 views

Why rockets are not tossed up before launch [duplicate]

Ok, I understand the nature of my question but anyway why the rockets are not tossed up before launch. It could introduce a huge handicap for a rocket in terms of reduced distance it has to travel, ...
1
vote
0answers
71 views

What are Spectr-R's major contributions to radio astronomy that could not have been done from Earth?

Spektr-R Spektr-R (37755, 2011-037A) is a Russian radiotelescope spacecraft in a very high orbit around the Earth. It's orbit is cis-lunar with an apoapsis of ...
1
vote
2answers
80 views

Which spacecraft can see plants “glow” during photosynthesis during the day, and what wavelength does it use?

This comment reminded me that I once read something about an Earth observation satellite that has a sophisticated optical system (possibly a camera) that it tuned to a very narrow range of wavelengths ...
3
votes
1answer
45 views

How can I convert HGI coordinates to J2000 coordinates?

I am looking at old mission data such at this one from Vega 1. The coordinate system provided is HGI. Most of the data I have is in ICRF/J2000.0, as JPL Horizons provides. How can I convert between ...
3
votes
1answer
71 views

Will Parker Solar Probe's orbit eventually circularize?

I was playing around with Universe simulator 2 and they have simulated NASA missions. It seems to actually take care of n-body simulations surprisingly well- in terms of a video game that is. So I was ...

15 30 50 per page