# All Questions

10,659 questions
144 views

### Does NASA no longer own a “Vomit Comet?”

This Wikipedia article seems to suggest that NASA no longer owns an aircraft capable of simulating weightlessness, and that such astronaut training is now contracted from a private company. Can this ...
2k views

### Why did the Herschel Space Telescope need helium coolant?

Inspired by answering this question The Wikipedia entry says this On 29 April 2013, ESA announced that Herschel's supply of liquid helium, used to cool the instruments and detectors on board, had ...
172 views

### Where did the Herschel Space Telescope go in 2013?

The Herschel space telescope wins as largest optical telescope mirror in space when "optical" includes far infrared (~55 µm). The Wikipedia article Herschel Space Observatory lists the orbit as ...
420 views

### What's the largest optical telescope mirror ever put in space?

As a follow-on question to What's the largest optical lens put in space? I'd like to ask about mirrors this time. Question: What's the largest optical telescope mirror ever put in space? Optical ...
62 views

### Load Relief of a launch vehicle [closed]

What is the exact meaning of load relief during the Ascent phase of a launch vehicle? How does the launch vehicle control is affected by the angle of attack of the vehicle?
20k views

### What makes Ada the language of choice for the ISS's safety-critical systems?

We have it on good authority that Ada is widely used for "safety critical software" on at least the US side of the International Space Station. Of all the possible languages to choose from, what are ...
13k views

### What language is software running on the ISS written in?

What is the coding language used for the software used on the ISS? Is it NASA's own coding language, or is it something like C, or C#, maybe Haskell?
107 views

### What makes Space Adaptation Syndrome worse?

Are there any particular movements or activities that exacerbate SAS, space sickness?
78 views

### How are martian dust devil maps made?

The Gizmodo article A Martian Dust Devil Swept Right Over NASA’s InSight Lander says: What’s unique about this most recent event, however, is that InSight was able to gather other forms of evidence ...
47 views

### IRIS Transceiver for LEO Missions?

My professor really wants to know if the IRIS transceiver, which flew on MarCo, will be used in LEO. In fact so much that he doesn't accept "no" for an answer. I have searched for an example but found ...
491 views

### What are the orbital-mechanical advantages of a long (100+ second) sub-orbital coast phase?

This answer to Trajectory to get into orbit says: In most real launches to low Earth orbit, the burn continues from liftoff until orbital insertion, without a coasting phase. Some (like Antares) do ...
9k views

### Do simulator games use a realistic trajectory to get into orbit?

In videogames (such as KSP or Spaceflight simulator) people put rockets in orbit with the following procedure: Turn on the engines and move vertically for a bit. Start a roll program to turn the ...
46 views

### What is the longest manned re-entry from Low Earth Orbit ever recorded?

What is the record for the longest amount of time that a manned spacecraft has taken to re-enter from low Earth orbit (LEO)? I would prefer the duration between the beginning of the re-entry burn ...
42 views

### If humans move to different solar systems will they eventually evolve into different species? [closed]

I once read an argument against space settlement in a newspaper that said that if humans move to different systems eventually they will evolve into different species, or their cultures and beliefs ...
608 views

### Why does NASA use higher frequencies even though they have worse Free Space Path Loss (FSPL)?

Looking at the Formula for FSPL we see that it increases with Frequency. Why is X-Band used for Deep Space Communications instead of lower bands like S-Band? Is it a question of data-rates? Is the ...
122 views

### What's the largest optical lens put in space?

While star cameras and wide angle cameras in space are built from glass lenses, large aperture optical systems generally use reflective optics. For some large ones see answers to What's the largest ...
997 views

### After the loss of Challenger, why weren’t Galileo and Ulysses launched by Centaurs on expendable boosters?

The Centaur upper stage, the first hydrolox rocket stage ever flown and (in its highly-evolved forms) still one of the most-used, as well as one of the highest-performance (if not the highest-...
554 views

### Are there cubesats in GEO?

This answer to the question How often do reaction wheels require desaturation, normally? says: One practical example I know of is for a 6U in GEO that is always sun pointed, there's a thruster ...
77 views

### Why does LRO's laser altimeter telescopes use lenses instead of mirrors?

From Space.com's NASA's Piggyback Experiment on Israeli Moon Lander Could Aid Future Lunar Touchdowns shows an image of the laser altimeter on the LRO. It looks like the "transmit" and "receive" ...
82 views

### Could Beresheet's retroreflector array (still) be used?

Almost the same question as Could Schiaparelli's retroreflector array (still) be used? except for Beresheet. Some important differences in this case: Beresheet was far less "crashed" than ...
54 views

### Can we calculate elliptical properties in a spherical coordinate system?

Can we calculate the elliptical properties like the semi-major axis and eccentricity using the state vectors (position and velocity) in the spherical coordinate system? http://www.braeunig.us/space/...
96 views

### What are these four “debris” objects along with the Starlink satellites?

Celestrak has an updated system of categories for retrieving lists of current TLEs, and there's already one for Starlink, yay! Currently https://www.celestrak.com/NORAD/elements/starlink.txt contains ...
106 views

### Apollo SM RCS specific impulse?

What is the specific impulse of the RCS thrusters on the Apollo Service Module? This document cites 281 seconds for the LM's RCS thrusters, but I cannot find similar specs for the SM.
46 views

### Deep Space Network's transmitter power versus frequency?

Just a general question: In regards to the Deep Space Network antennas, how does power from the transmitter of the antenna relate to the frequency used? I believe the antennas use X band frequency for ...
47 views

### Is the radiation exposure in a spacecraft window seat significantly different than other areas of the cabin?

Does an astronaut seated next to a window get more exposure to harmful radiation (and if so, which types of radiation) than an astronaut somewhere else in the cabin at the same time? Related: Is ...
94 views

### Under-expanded nozzle at sea level - is it a problem?

I'm designing a solid rocket motor with a fixed pressure in the combustion chamber $p_{cc} = 70~bar$. When it comes to the choice of the right nozzle, I have to consider the proper expansion ratio, in ...
2k views

### What are they doing to this rocket following its test fire?

Watching video of today's test of Northrop Grumman's OmegA first stage SRB after the test is over and the flames have died down a bit, it looks like they are sticking something into the back end of ...
286 views

### Can someone help Scott Manley explain this Snoopy-capturing maneuver?

In his recent video Apollo 10's Lunar Module Snoopy Is Lost In Space - Could We Bring it Home? Scott Manley uses some fancy supplemental techniques in KSP to simulate and explain a possible mission to ...
77 views

### How often are satellites in GEO moved to follow customer demand?

The BBC News article Inmarsat lays big satellite order with Airbus says: The firm is buying three new spacecraft to augment its Global Xpress system, which provides connectivity to on-the-move and ...
304 views

### What is the Process for Re-certifying Flight Hardware?

I was reading about how we reused the water tanks because they were still within their certified life-time and had two questions: When would a certification become VOID? I'd assume if the water ...
141 views

### What would cause the Shuttle's redundant computers to disagree?

The Shuttle had five AP-101 general purpose computers. As discussed in this question, the system was redundant and there was a voting process to eliminate a computer whose results disagreed with the ...
67 views

### How much do SpaceX's titanium grid fin geometrical parameters measure?

Does anyone know approximately what is the width, length, thickness and depth of the titanium grid fins used in the Falcon9 v1.1? I'm trying to make a 3D model on solidworks but can't find the ...
70 views

### Design of return trajectory from lunar polar orbit to Earth's atmosphere

Given a flight path angle, altitude and velocity at re-entry into the Earth's atmosphere, how do I go about designing the return trajectory from a polar orbit at 17km altitude about the lunar surface ...
181 views

### How often do reaction wheels require desaturation, normally?

I'm sure the answer to this question is, "it depends" but I'm hoping for a ballpark number here. Let's assume you design a smallish satellite to point at the earth while orbiting. You have the ...
87 views

### What is the requirement of spacer rings in solid rocket motors in sounding rockets?

I saw this report SOLID ROCKET MOTOR DESIGN L-CLASS, here as shown in FIGURE-8, they have charged the motor with grain segments with spacer rings in between. Can`t we charge the motor without any ...
39 views

### Using Differential Equations to model path of satelite around earth

I am new to GMAT and am hoping to use it to model the path of a Low Earth Orbit satellite around Earth. I am thinking of plotting the path on a plane and using polar coordinates to model the path ...
35 views

### How actively is Deep Learning being used in exoplanet identification? [closed]

Papers, like this one from Google, show that Deep Learning and Machine Learning are effective in detecting exoplanets from luminosity data provided by telescopes like TESS or Kepler. These models ...
89 views

### What is the limiting factor for cargo throughput per launch to the ISS?

Given the high availability of ISS Commercial Cargo launches for NASA, it would seem that the aerospace stereotype of "mass reduction is paramount" may be outdated. What is the current limiting factor ...
133 views

Today's Teslarati article SpaceX wants to offer Starlink internet to consumers after just six launches talks about the new website https://www.starlink.com/ shows several images from it, and tries to ...
137 views

### Which Apollo-era contractors are still building aerospace components today?

This list of major Apollo manufacturers is from Chariots for Apollo. Which of them still make aerospace (spacecraft or aircraft) components today? AC Delco: inertial measuring unit, gyroscopes ...
18 views

### Convert ICRF to Body-fixed coordinate for Earth or Lunar. (MATLAB)

I want to find the position (x, y, z) of the satellite around the Lunar. I use the gradient of the gravitational potential to get an equation of motion of x, y, and z-direction in inertial coordinate. ...
87 views

### How much Delta-V is needed for Orbital Maintenance?

My question is aimed at understanding the how much Delta-V is needed for orbital maintenance for different orbits. Obviously, there still is some residual air resistance that decreases as the orbital ...
123 views

### What are the biological effects of a toe-to-head force gradient upon a human over the long term?

This question pertains to the notion of constructing rotating spacecraft and habs for human use in space in order to mitigate the effects of microgravity. Such craft have been a staple of many sci-fi ...
40 views

### What is the closest one could get to a black hole and still stand a _realistic_ chance of escape? [migrated]

This question is inspired by the one asked here: Is there any stable orbit around a black hole? and I note that (though I've heard of these before) there are, apparently, 3 important fundamental "...
49 views

### How frequent do TLEs of LEO satellites change?

I was doing some MATLAB simulations on LEO satellites using TLEs obtained from n2yo websites and I observed that n2yo was displaying a different TLE for the same satellite after a few days. I don't ...
159 views

### Delta-V of Starlink Satellites

The recently launched Starlink satellites are designed to use their HAL Ion thrusters to seek their own independent orbits, evade collisions, and de-orbit at the end of their lives. That's a lot of ...
34 views

### How does the JEM/Kibo connect to the “Porch Module”?

In this answer I saw Figure 35 of the encyclopaedic ISS Interface Mechanisms and their Heritage also shown croped below, and in this answer I see the second image (though an SE/imgur bug shows it with ...
6k views

### Why use water tanks from a retired Space Shuttle?

In 2015, technicians entered the retired Space Shuttle Endeavour to remove the water tanks, with the goal of reusing these tanks on ISS. The space shuttle Endeavour is retired and on display at the ...