# All Questions

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### James Webb Space Telescope Velocity Loss Formula or how fast will JWST be going on L+26

I was never great at math but now I wish I would have taken it more seriously. We have an office bet going and I need to come up with a formula to figure out the future velocity the JWST. I was able ...
2k views

### Why was it necessary to monitor the water quantity in the space shuttle?

In space shuttle's operators manual, Page(4.1-4), it is written as: The H2O quantity is determined by a PVT calculation based on H2O tank pressure and temperature transducer readings as well as GN2 ...
3k views

### Why is this Planet Labs video wobbly?

Planet Labs recently tweeted ( https://twitter.com/planet/status/1481790983155044352 ) a video showing a Falcon 9 first stage landed on a pad. Strangely, the image looks like it was taken by a camera ...
98 views

### New spin on laundry day: How will ISS cope with washing machine vibration and angular momentum?

Although the ISS currently has no laundry facilities, NASA’s Glenn Research Center sponsored a washing machine design contest to do the drudgery during spaceflight. Plans have been made for testing a ...
837 views

### When and why did three-axis stabilization become prominent in geostationary satellites?

Since the very first Sycom 1, geostationary satellites from 1960s to 1980s are cylindrical with solar cells covering the body of the satellite. Such examples include: GOES 1 to 7 AsiaSat 1 and its ...
191 views

### Starting refueled in LEO, how much payload could a heat-protected Starship softly land on Mercury after a gravity assist from Venus?

This question may be a crucial follow-up to this one because in this answer it is calculated that the payload to Mercury without a gravity assist would probably be minimal, so if already a moderate ...
2k views

### Could fuel cells of the Space Shuttles have been restarted in the case of a total power failure?

Reading the flight crew operating manual of the Space Shuttle I discovered that: The three fuel cells could have been stopped and restarted (unlike previous Apollo missions) The fuel cell start ...
51 views

### How to make diamagnetic lunar simulant that would "float" in a strong enough magnetic field? (for China's 60 cm high field simulator)

Live Science's China builds 'artificial moon' for gravity experiment says: Chinese scientists have built an "artificial moon" research facility that will enable them to simulate low-gravity ...
59 views

### How many hours/week on the ISS is spent on science vs maintenance?

This was asked in 2016 : Does ISS crew exercise time count toward their X hour work week? The answer as of 2016 was 40 hours / week for a crew of 6. But as noted there, when the crew size increases to ...
21 views

### What fraction of the Kapton thickness on the ISS' solar panels was likely eroded throughout their lifetime? Predictions? Measurements?

Background @Tristan's answer to How are the silicon PV cells constructed in the ISS's solar panels? Are they as flexible as they appear here? informs us that Kapton is part of the "blanket" ...
66 views

### What was the first spacecraft intentionally moved from GEO to the graveyard orbit to die? (just a bit above geosynchronous)

Why “super” for supersynchronous orbits? Why not “trans”? and discussions and answers there got me wondering: Question: What was the first spacecraft intentionally moved from GEO or geosynchronous to ...
48 views

### What was the first spacecraft intentionally placed in a supersynchrous Earth orbit? (period longer than a sidereal day)

Why “super” for supersynchronous orbits? Why not “trans”? and discussions and answers there got me wondering: Question: What was the first spacecraft intentionally placed in a supersynchronous Earth ...
72 views

### Description of jwst data acquisition pipeline

I am attempting to try to obtain some proficiency in reviewing and analyzing JWST data. Toward that end, I have installed python language jdaviz environment and files and JWST python environment and ...
49 views

### Cost breakdown of launch companies

One thing which I recently heard Peter Beck say in an interview with Tim Dodd was that the cost of running a launch company isn't primarily driven by the rocket itself, but the operations required to ...
135 views

### Does the James Webb Telescope have a Two Line Element set?

How do you track the position of the James Webb telescope? Does it have its own TLE, or...?
677 views

### Are In-Flight Electrically Heated Steam Rockets Possible?

I wonder if a rocket that uses electricity from internal batteries to heat water in its tanks to high pressure would be able to use that pressure to take off. Is it possible? I've researched here and ...
4k views

### Why are the JWST A3 and A6 position sensors different from all the others?

Copied from the Nasa.gov site 'Where is Webb?' NOTE: Segment A3 and A6 will be moved separately at the end of the process because their position sensors are read out in a different way. Why would ...
426 views

### Why do EVA suits have legs?

Why do EVA suits have legs? Planetary exploration suits (PES) obviously need legs. Spacesuits with legs are “a classic icon of human space exploration” and a requirement for mobility. https://www....
26 views

### GMAT B-Plane to Mars different date

can anybody help me to find how to change the date to the exercise of GMAT in order to work anyway? I'm not able to solve this problem. Thanks
823 views

### How long would it have taken to launch an Apollo contingency flight?

How long would it have taken to launch an Apollo contingency flight, if, for example, the lunar lander couldn't have got back up to orbit? Could the lander have held three astronauts?
54 views

### Fuel profile for Apollo 11

I downloaded a dozen of NASA documents about post-flight analysis of Apollo 11 mission, but I cannot find a table or a plot of fuel usage and remains; Some of the documents which I found: http://www....
177 views

### What is the largest possible rocky body? [closed]

Suppose you start with a rocky sphere about 12,742 kilometers in diameter and continuously add more rocky material such that you don't smash this sphere to bits. What is the upper limit for this? ...
83 views

### ISS propagation becomes much more accurate with reduced drag. Any ideas why?

I have currently been testing my implementation of a numerical propagator with the ISS. Without going into much details, the propagator considers Earth gravity (with the GGM03S model including zonal, ...
106 views

### Pressurized gloves have significant limitations. What are objective advantages/disadvantages of the alternatives? [closed]

Conventional EVA suits suffer from mobility and tactile sensory limitations due to their pressurization. Any articulated container which changes volume with motion will resist motion if pressurized. ...
72 views

### Has a cubesat ever caused a problem for another spacecraft? Examples? Close calls?

Cubesats can pose some unique challenges; they are small and so potentially a little harder to track, have larger area/mass so more subject to forces that can change their trajectories, are often less ...
88 views

### What are all these packages attached to a side module of the ISS? How did they all get there?

Ars Technica's New images of the International Space Station reveal that it is still a jewel includes the photo below and I've added a view of a side module with a collection of various rectangular ...
66 views

### Are circuit diagrams available for the Voyager spacecraft telecommunications systems?

I'm particularly curious about the coherent transponder mode where the outgoing transmitted signal is phase-locked to the incoming received signal (prompted by @uhoh's recent question). This is a mode ...
3k views

### If one Starship can transport 100 people to Mars, how many could it safely land near Mercury's north pole after one Hohmann-like transfer?

Personally, I would rather live near Mercury's north pole than anywhere on Mars mainly because: The permanently shadowed craters harbor abundant water ice and other frozen volatile materials Mercury ...
415 views

### Is JWST going to be in antumbra at L2?

I read the years-old comments in this question & found a new question waiting an answer. Is JWST going to be in antumbra (aka annular Earth eclipse) in its halo orbit around L2? I was of the ...
149 views

### Curvature of the JWST mirrors

The JWST has four mirrors. The large primary mirror made of 18 hexagonal mirrors The secondary mirror The fixed tertiary mirror The flat fine steering mirror I found very little information about ...
116 views

### Are Interplanetary mission trajectory computations based entirely on Newtonian mechanics?

I am wondering if the application of General Relativity is ever needed(?) I assume that Newtonian mechanics is sufficient with some trajectory corrections applied as needed on route. I also assume ...
47 views

### Speed and Temperature Data History for JWST? [duplicate]

Is there a source for data on velocity and various temperatures of JWST? I would like to see a graph of the data.
76 views

### How is a desired chamber pressure achieved in a liquid rocket engine

Before everyone responds that this has been asked before, I have read through every relevant post I could find here and believe my question has not been clearly covered. I also understand that "...
3k views

### James Webb orbit insertion

Webb will issue a final course correction burn to insert it into the orbit around L2. It arrives from earth so the approach velocity should be higher than the desired orbit velocity and the vector ...
115 views

### Why “super” for supersynchronous orbits? Why not “trans”?

I was just getting used to “cis” and “trans” for orbits inside and outside the Lunar orbit. “Trans” is a Latin word root meaning “across, beyond, or through”(Meriam Webster). “Trans” seems like a ...
133 views

### Does NASA document what it contemplates? "NASA had already been contemplating a costly and risky robotic refueling mission" for JWST

Ars Technica's All hail the Ariane 5 rocket, which doubled the Webb telescope’s lifetime says: Because ten years seemed like a fairly short operational period for such an expensive and capable space ...
26 views

### Fjeldbo, Kliore, & Eshleman 1971 Fig. 22 planetary atmosphere index of refraction increasing with altitude; physics insight or convenient abstraction?

this answer to Is it possible for a spacecraft to communicate with Earth when a planet is in the way? suggesting that atmospheric refraction could be used to get at least some kind of signal around a ...
46 views

### Are there uses for these 'quasi iso-propic' supersynchronous transfer orbits?

In my answer to What are the benefits of supersynchronous transfer orbits? I stumbled upon an interesting outcome when considering the total $\Delta V$ cost from an inclined low altitude parking orbit ...
227 views

### When is the supersynchronous orbit more efficient than a typical Hohmann transfer where inclination change and circularization are simultaneous?

The title essentially explains it all. Some GEO launch vehicles like Proton, which launches from Baikonur at a latitude of 46 degrees, launch into a supersynchronous orbit. So at what point is the ...
202 views

### Can the JWST deployment steps be reverted?

I think, if something does not work (had not worked), or some improvisative solution is needed to handle an unexpected problem, then it would significantly improve the configuration freedom if the ...
44 views

### Please explain a way of calculation of Lagrange multiplier in algorithm of low thrust transfer

In David Vallado's book 'Fundamental of Astrodynamics and Applications', chapter 6.7. ("Continuous-Thrust Transfers") there is an algorithm #47: Low Thrust Transfer. In this algorithm a ...
751 views

### Why are uncertainties of orbital state vectors provided as covariance matrixes?

I have recently become interested in testing a numerical orbital propagator with ISS ephemerides, following @RyanC's suggestion in this answer. Ephemerides for the ISS seem to be publicly available in ...
116 views

### Is it possible to transfer electricity by creating an ionized air path using ionizing laser [closed]

I have a theoretical question, if we use some sort of ionizing radiation like an ionizing laser for example (https://en.wikipedia.org/wiki/Atmospheric-pressure_laser_ionization), to create a path in ...
12k views

### Is there any point in space that the James Webb Space Telescope would be unable to image?

The James Webb Space Telescope has some very specific positioning requirements; the second Lagrange point and the heat shield positioning being at the top of my mind. Do these constraints eliminate ...
192 views

### How likely are atomic bomb tests to be detectable by human-equivalent extraterrestrial life?

In brightness, a nuclear detonation is comparable to the Sun. Source: "The light of the Atomic Bomb," Clay P. Butler, Science Vol. 138 No. 3539 pg. 483-489, 26 October, 1962 How likely are ...
1k views

### What are the benefits of supersynchronous transfer orbits?

Some satellites are injected into higher apogee than standard GTO apogee of 35 786 km. Next the satellite then has to increase its perigee ( usually 250 km ) to GEO altitude. Then the apogee has to be ...
369 views

### Why is NASA choosing such a large “halo” orbit at L2 for JWST?

According to “https://webb.nasa.gov/content/about/orbit.html”, NASA plans to exploit a quarter million mile radius “halo” orbit at L2. And Webb will orbit around L2, not sit stationary precisely at ...
137 views

### Why did NASA never launch crewed Orion missions on a Delta IV Heavy to the ISS?

Following the successful EFT-1 mission, why didn't NASA start launching crews to the ISS on the Orion spacecraft? This question deals about why crews weren't sent to the Moon, but I wonder why wasn't ...
402 views

### Why does light from 180M years cosmic time take 13.6B years to reach us? [closed]

If all goes well, JWST will allow us to witness events that occurred roughly 180 million years cosmic time (after big bang). Apparently this light arrives 13.6 billion years after it was emitted. In ...
123 views

### Travelling close to speed of light

I have theoretical questions about inter-stellar travel at very high speeds (e.g. 0.9c). The inter-stellar medium is not a perfect vacuum, there are about 1 atom per cm3. This causes some friction. I ...

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