# All Questions

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### Rocket Engine - Actuator in Loop Simulations

For Actuator-In-Loop simulations, why are the rocket engine nozzles along with the thrust vector control assembly (including the actuators) kept inverted on a platform like in the attached image or as ...
62 views

### What damage/repairs have to be done to the launch pad every time SpaceX launches?

As SpaceX is a company that is very focused on rapid reusability, low-cost operation and a philosophy of "the best part is no part", what repairs have to be done to the towers and general ...
52 views

### What would Red Dragon's realistic payload mass be?

So SpaceX's Red Dragon is unlikely to ever fly. But if it had, what would it's realistic payload to the surface be? How significant would the payload penalty be if the capsule itself was built to ...
1k views

### Why use a Mars orbital Earth return vehicle for sample return?

NASA's plan is to use two separate missions to bring home the drill core samples that the Perseverance rover will take. The samples will in plan be picked up by a landed mission and launched to Mars ...
39 views

### How is matter (volume, shape, density etc.) also distorted by the warping of space-time? [closed]

How matter is defined or affected by the shape of space. For instance, what happens to the shape of matter when it enters a gravity well, or washed over by a gravitational wave? Does it become smaller,...
66 views

### Is Crew Dragon rated for any non-Spacex boosters?

The Spacex crew Dragon uses the Falcon 9 for its orbital launches, and is not set to ever use a different launcher. However, an uncrewed Dragon will probably launch on the Falcon Heavy, as is planned ...
478 views

### How does spin stabilization intuitively work?

I am not very familiar with physics or rocketry and I am having a lot of difficulty grasping why spinning a rocket or satellite stabilizes it. Most sources I have looked at have said either that it ...
69 views

### Error in Propagating equatorial orbit using GMAT

I propagated an orbit with semi-major axis of 7000km and the rest of the keplerian orbital elements 0 on GMAT. Since the orbit is circular and in the Equatorial plane, it should not change over time. ...
68 views

### Delta-v change for station keeping

I was simulating the GMAT examples, one of them called LEO station keeping, this simulation gives me the delta-v needed to maintain orbit. I noticed that not all orbital transfers (for station keeping)...
104 views

### How to calculate the local maximum solar radiation on Mars from day to day throughout a full martian year?

I would like to know where on Mars the least lowest daily temperatures depending on the time of year will be. At first glance one might think, as I did, that it has to be along its equator, but ...
47 views

### When and when not to use the SDLS protocol?

When should the features provided by the Space Data Link Security Protocol (SDLS) be applied to TM Data Space Link Protocol communications? This is with respect of ensuring protection within the ...
136 views

### Is this soot building up on the Falcon 9 interstage?

In the below video of stage separation during Falcon 9's CRS-19 mission, the exhaust of Stage 2's Merlin 1D-Vac impinges on the interstage. It also deposits a black substance on the white paint. Is ...
97 views

### Capturing Hydrogen from the solar wind for Space Colony / Terraforming

Could we capture hydrogen from the solar wind instead of importing it or getting it from local sources ie water on mars or the lunar ice? Would it be worth the time vs energy used to get it? Basically ...
141 views

### pitch, yaw and roll

Imagine a spacecraft in space, which is required to dock with other. Presume that it needs to "pitch" by X degrees, "yaw" by Y degrees, and "roll" by Z degrees (although &...
305 views

### Why is Perseverance's RTG lifetime only 14 years?

The MMRTG uses Pu-238, which has a half-life of 87.7 years. So after 14[1] years it should be able to output a little over 80% of the power, which naively to me seems like it should be enough. What is ...
97 views

### State of Starman?

If Starman had been human and not a dummy, what would their state be now? Preserved or decayed? Dried? Frozen?
79 views

### Could the SS520 be used to return a payload from Mars to Earth?

The Japanese SS520-5 nanosat launcher has a payload of 5kg or so to LEO on an all solid fuel rocket with a total mass of about 2.6 tons. To reach LEO its delta-V totalled over all three stages must be ...
59 views

### Did any sounding rocket ever fly through a noctilucent cloud?

Noctilucent clouds are the highest clouds forming above the Earth, up in the mesosphere. They form in late spring / early summer and above latitudes closer to the poles. Was a sounding rocket ever ...
123 views

### Why isn't the Kármán line itself considered to be in outer space?

The Kármán line is the altitude at which the atmospheric pressure is so thin a craft would need to achieve orbital velocity in order to maintain enough aerodynamic lift and control. Therefore, ...
18 views

### Pointing accuracy and relevant manoeuvers CUBESAT

How do you calculate or determine the pointng accuracy of your CUBESAT in sunlit-part and eclipse-part modes? Also how do you determine the maximum roll/pitch/yaw angles and slew rate required in ...
192 views

### What exactly gives a larger field of view to the donated “spy” telescopes that NASA may send to Mars? How much larger?

This answer links to Space.com's NASA May Launch Donated Spy Satellite Telescope to Mars which emphasized textsays: An unexpected gift The two donated telescopes were apparently built for a National ...
61 views

### Find the jump condition of the mass costate of a Launch Vehicle ascent problem solved via an indirect method (Pontryagin Minimum Principle)

I'm trying to solve a trajectory optimization problem for a class of problems like the old Altas-Centaur SLV3 Centaur launch vehicles. Those are a stage and a half design where the 2 LR-87 engines ...
80 views

### ISS Docking / Undocking schedule availability

Is there a website or other API from where the ISS planned docking / undocking events could be available? I would also be interested in historical docking undocking events. Thank you very much in ...
65 views

### Keplers equation: written in change in eccentric anomaly

I am reviewing the "Fortran Astrodynamics Toolkit (can be found here) and even more specifically at the two body propagation method implemented in this Kepler module for elliptical and circular ...
65 views

### How was each Space Shuttle contingency rescue missions numbered?

Reading the wikipedia article on STS-3xx, I noticed that the numbering does not seem consistent. Space Shuttle contingency rescue missions were all numbered in the 300s with the exception of STS-400, ...
35 views

### Resources for number of orbiting and active satellites by year?

What are the standard resources for numbers of all orbiting as well as specifically active satellites by year? I'm interested in finding information on how many satellites were in orbit and how many ...
62 views

### Need help finding a clean expression for exit velocity

I'm trying to calculate a engine burning LOX and ethanol (96%) and for that I am using both CEAgui, a GUI for NASA's CEA (Chemical Equilibrium with Applications) code Sutton's Rocket Propulsion ...
5k views

### Could one of the interstellar probes discover Planet IX by accident?

Could one or some of the spacecraft sent beyond the Kuiper belt discover (or even disprove) the hypothetical Planet IX? That doesn't necessarily mean coming so close you'd recognize the planet in ...
83 views

Good day, I am currently doing a project for university in which I have to redesign the connector support for the Payload Adapter (PLA 1194 VG) for the Vega(picture shown). I would like some ...
2k views

### Why don't astronauts email their inventory?

I was looking at the SpaceX Dragon capsule reentry. At some time after wake-up Bob gave a precise account of what was consumed from which bag. So many bottles of water, so many breakfasts, this bag ...
67 views

### What is the constant g-phase in Apollo re-entry, and why does it not show up on the graph?

On the Apollo 11 Flight Journal Day 9: Re-entry and Splashdown, it says something about the "Constant g-phase". This is what the ALSJ says: Planned drag level (deceleration) during the ...
1k views

### At what altitude did the Skylab space station disintegrate?

On the Wikipedia page it is written that SkyLab's reentry began at 16:37 UTC on July 11, 1979. But neither on the page nor in the source is it written how high the Skylab workshop started ...
26 views

### Could one use an adjusted idealized greenhouse model to calculate the local average temperature on Mars?

The Idealized greenhouse model article on Wikipedia gives the following solution for finding the global surface temperature on an idealized planet with an atmosphere: T_s = [ \frac{S_0(1 - \alpha_p)}...
80 views

### Thruster firing time for station keeping

I am simulating the example of LEO station keeping in GMAT with a delta-v thrusters of 2.5m / s, my question is how can I determine the time in which the thrusters act to raise the height of the orbit ...
5k views

### Why exactly does Curiosity's RTG make more electricity on cold days?

There is a fascinating factoid in this answer to MMRTG- thermal and electrical output: The electric power of the thermocouples depends on cooling influenced by the environment. On a cold day on Mars ...
168 views

### How to fit, into a cubesat, 29 trackable high drag subsatellites with well-defined aerodynamic profiles

Johnathan McDowell's recent tweet says: The @AerospaceCorp Aerocube-10a cubesat carries 29 small passive high-drag subsatellites used to probe the density of the upper atmosphere. 3 have been ejected ...
70 views

### Were there any experiments that produced rocket fuel grade methane on mars?

One of the main reasons that Spacex's Starship engine raptor uses methane is because it is present on mars. Where there any experiments that used the methane on mars to produce rocket fuel? Something ...
31 views

### Is a 2:1 “figure-eight” Lissajous orbit possible in the Circular Restricted Three Body Problem?

Was Queqiao in a halo or Lissajous orbit? Why do sources disagree? says Proper halo orbits have the same period for their in-plane oscillations and out of plane oscillations, so they are closed ...
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### Was Queqiao in a halo or Lissajous orbit? Why do sources disagree?

Wikipedia's Lissajous orbit says that sources disagree on the nature of Queqiao relay satellite's orbit; if it was in a proper halo orbit or just a Lissajous orbit. Proper halo orbits have the same ...
329 views

### What is the largest proper cubesat?

The sizes of Cubesats are measured in "U" units of volume. Each U is nominally a cube of something like 10 to 12 cm on a side, depending on the specific deploying mechanism it's approved for....
75 views

### MMRTG- thermal and electrical output

I haven’t been able to find a definitive number for the thermal output (in watts) of the MMRTG used aboard the Perseverance rover. The numbers I’ve seen range from 1950 watts to over 2000. I also ...
88 views

### Fuel used for electric propulsion?

What kind of fuel do electric propulsion spacecraft and satellites use? Did any of them get electricity from bateries? An ion engine creates thrust by accelerating ions using electricity. How is that ...
43 views

### Has a suborbital rendezvous ever been mentioned in a serious mission proposal/study? [duplicate]

This is an odd one that's been in the back of my head for a while. Consider the LOR architecture of the Apollo missions. To return to earth from the lunar surface, it is most mass-efficient to have ...
157 views

### Taking custom software or hardware to the ISS

Before departing to the ISS, astronauts are allowed to pack some personal objects to be taken with them (see other question about packing). What if an astronaut had some self-written software (for ...
29 views

### Most busy times in space launches by decade?

If anyone has the curiosity and time and possibility to run the scripts, I think it's interesting to see the most busy day, week, month and year, by decade. Most busy week of 1960s then most busy week ...
82 views

### Is it possible to send a CubeSat to Saturn/Enceladus?

I was wondering if it is technologically possible to send a CubeSat/Nanosatellites or constellation of nanosatellites to explore the water vapor jets in the southern region of Enceladus in the Saturn ...
41 views

### What is the splash down speed of the manned dragon capsule?

What's the rated speed of the crewed dragon capsule? Do we have any data on the actual measurement for the demo mission? I'd also appreciate any info on speed for Soyuz, other soviet manned, Apollo, ...
769 views

### Getting back from the Moon

This link describes the way back from the Moon surface to the orbiting spacecraft. But how could that spacecraft get back to the Earth? It is a long journey. How much rocket fuel would be needed, in ...