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7
votes
3answers
2k views

How to calculate the planets and moons beyond Newtons's gravitational force?

The question Calculating the planets and moons based on Newtons's gravitational force was pretty much answered with two items: Use a reasonable ODE solver; at least RK4 (the classic Runge-Kutta ...
34
votes
3answers
14k views

Effect of atmospheric drag on rocket launches and benefits of high altitude launch sites

What is the approximate influence of atmospheric drag on the cost of rocket launches? Is it beneficial to have launch sites located at higher altitudes? Cape Canaveral is at sea level, but I've ...
12
votes
2answers
3k views

How to calculate data rate of Voyager 1?

I've read the following passage in the answer to the Quora question How can Voyager send a signal strong enough for us to receive, in spite of its enormous distance from us? And how can it have the ...
77
votes
6answers
12k views

How much bigger could Earth be, before rockets wouldn't work?

hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body. I'm looking for a number ...
14
votes
2answers
1k views

Is this what station keeping maneuvers look like, or just glitches in data? (SOHO via Horizons)

I've been enjoying the JPL Horizons web interface and after I discovered the incredibly extensive database associated with SOHO (Solar and Heliospheric Observatory, also see sohowww.nascom.nasa.gov) ...
12
votes
3answers
2k views

What would a “Kármán plane” look like, a bird, or a plane?

If I understand correctly (which I might not), the Kármán line is roughly the altitude where a "Kármán plane's" upward lift force at the orbital velocity for that altitude would be equal in magnitude ...
11
votes
3answers
4k views

How to best think of the State Transition Matrix, and how to use it to find periodic Halo orbits?

I'll state my mathematical question about the state propagation and state transition matrices first, then show you a simple problem for which I would like to use these concepts to generate a densely ...
10
votes
1answer
5k views

Why is a near rectilinear halo orbit proposed for LOP-G (formerly known as Deep Space Gateway?)

Why is a near rectilinear halo orbit a good place for a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway)? Are there specific logistical and orbital-mechanical advantages over ...
3
votes
2answers
756 views

How do SDP4's “Deep space” corrections to SGP4 account for the Sun's and Moon's gravity?

The Simplified Perturbations model SGP4 is used to calculate Earth satellite state vectors (position and velocity) using standard ephemeris data encoded as TLEs (Two Line Elements). According to ...
22
votes
4answers
8k views

Starman/Roadster in a=1.795 AU orbit, now what's the method to this madness?

The question SpaceX's 4,425 satellite constellation - what's the method to the madness? received an excellent answer explaining the rationality behind the madness plan. Elon Musk's tweet (spotted ...
13
votes
1answer
15k views

What is a near rectilinear halo orbit?

A proposed option for the lunar orbit of a Lunar Orbital Platform-Gateway (formerly known as Deep Space Gateway) is a near rectilinear halo orbit, or NRHO. This excellent answer discusses the ...
31
votes
7answers
12k views

How could a 90 m/s delta-v be enough to commit the space shuttle to landing?

Wikipedia claims (although with no citation) that in order to make the space shuttle land, an initial powered delta-v of 322 km/h was applied in orbit, retrograde to the shuttle's orbit. 322 km/h is ...
28
votes
6answers
3k views

What technological hurdles prevent the development of a space gun?

Ever since Jules Verne wrote "From the Earth to the Moon" space guns have long been proposed as a method of launching objects into space. And for non-human, non-fragile payloads they make sense as the ...
25
votes
2answers
2k views

How did the tangential thrusters for the 2014 LDSD test spin-up then spin-down so nicely?

I just watched the NASA JPL video of the 2014 test of the Low-Density Supersonic Decelerator (LDSD). Tangential thrusters are used to spin up the craft for stability before the main rocket ignites. ...
10
votes
2answers
3k views

General guidelines for modeling a low thrust ion spiral?

I've been told that for low thrust ion spirals, delta V would be the difference between speeds of departure and destination orbits. For example the delta V between a 7.7 km/s LEO and a 3.1 km/s GEO ...
33
votes
3answers
43k views

How to programmatically calculate orbital elements using position/velocity vectors?

I would like to build some orbital mechanical software from scratch. I feel that this would be a great way to learn the steps required to calculate different Kepler orbital elements of an object, plot ...
45
votes
11answers
38k views

Could it be possible to launch a rocket from a balloon?

There are several (commercial) organisations looking into alternative means to launch space-bound rockets. One commonly proposed method is to use a large airplane as the launch platform. This method ...
24
votes
1answer
3k views

SpaceX's 4,425 satellite constellation - what's the method to the madness?

The BBC article SpaceX aims to launch internet from space discusses the SpaceX proposal for a dense array of over 4,000 LEO satellites for global internet coverage, and links to SpaceX non-...
29
votes
1answer
58k views

What is the current cost-per-pound to send something into LEO?

As a student of economics and finance I would love to learn more about the cost structures of sending a payload into orbit. More specifically - What is the cost-per-pound to send something into LEO ...
26
votes
4answers
4k views

Does the NK-33 engine require subcooled kerosene so cold that it turns to wax?

It was mentioned in this answer and in several other places on the internet that the kerosene fuel used by NK-33 engines needed to be subcooled enough so that it reached the same density as the LOX, ...
32
votes
3answers
35k views

How much power would a spacecraft's magnetic shield require?

I've read over the decades that a magnetic shield might protect a spacecraft from cosmic radiation. Its a fascinating idea that might only be theory or science fiction at the moment. In regards to ...
52
votes
2answers
44k views

What is the purpose of the jets of water often under rocket engines during launch?

I have watched several STS launches, and noticed that there were always huge jets of water that would begin right before the rocket engines lit. They were right under the rocket, mounted to the pad. ...
28
votes
4answers
9k views

How is the altitude of a satellite defined, given that the Earth is not spherical?

The altitude of a satellite is the distance between the Earth's surface and the satellite, but the Earth itself is not spherical. At the equator the Earth's radius is 21 km more than at the poles, and ...
5
votes
1answer
507 views

How can I verify my reconstructed gravity field of Ceres from spherical harmonics?

Based on @DavidHammen's very helpful answer I've made progress reconstructing the gravity field of Ceres from the Dawn radiometric data. The question there contains further information, but suffice it ...
17
votes
5answers
5k views

What artificial satellite has the farthest orbit around the Earth?

What is the furthest Earth orbiting satellite? What is its speed and purpose?
3
votes
2answers
897 views

How can the two MarCO cubesats remain reliably close to InSight during their six month trip to Mars?

According to the NASA JPL web page Mars Cube One (MarCO) Mission Overview and the YouTube video MarCO: First Interplanetary CubeSat Mission linked there, after the Centaur upper stage deploys InSight, ...
19
votes
3answers
2k views

How much can the Mars rover Curiosity do autonomously, after four years of operation?

I was under the impression (when asking this question) that over the past four years that experience by ground operators and programmers had lead to a configuration where the Mars rover Curiosity ...
5
votes
2answers
3k views

How does one dogleg from Florida to a sun-synchronous orbit?

From NASA Spaceflight's article SpaceX Falcon 9 launches first NRO mission with NROL-76: The NROL-76 launch was not to be targeting a sun-synchronous orbit, typically used by the NRO’s optical ...
32
votes
2answers
15k views

Will the ISS need more docking ports?

Currently the ISS has two basic segments, the Russian and US sides. The Russian side has 4 docking ports. Usually occupied by 2 Soyuz, 1 or 2 Progress freighters or an ESA ATV vehicle. You can see ...
12
votes
1answer
1k views

Are some Halo Orbits actually Stable?

UPDATE: I found another reference! While I always enjoy a good video starring Jimmy and Linda Carter, this one has Dennis Wingo describing ISEE-3's original Halo orbit. He describes Sun-Earth $L_1$ as ...
9
votes
1answer
4k views

How have space suits dissipated the heat removed from astronauts?

I never thought about this until reading the comments below this answer. To radiate something like 150W (a very conservative lower limit of human + suit systems heat production - see @Uwe 's comment ...
18
votes
3answers
2k views

What's the largest aperture telescope sent beyond the Earth-Moon system?

The question and answer about telescopes sent to different planets got me wondering. There are so many solar system bodies that have been photographed by deep space spacecraft, planets, dwarf planet(s?...
13
votes
2answers
837 views

Why is FAI considering lowering the Karman Line to 80km?

I ran across this FAI statement The Karman line is the 100km altitude used by FAI and many other organisations to mark the “boundary” of space . In the last few years there have been many scientific ...
24
votes
9answers
4k views

Puzzler - which spacecraft(s) incorporated real wood structural elements?

Not a trick question, but a real puzzler - which spacecraft or spacecrafts incorporated real wood structural elements?
11
votes
1answer
590 views

What sort of orbital elements are used to describe halo orbits?

For standard orbits we can use Keplerian elements, TLE, or other similar. These don't make much sense for Halo orbits, which are not around a central body, but around a Lagrangian point, and follow an ...
6
votes
2answers
1k views

Did the NASA PhoneSat actually try to use the GPS from the phone itself?

I was reading this article about NASA's PhoneSat Flight Demonstrations and came across this sentence. "To achieve this, NASA's PhoneSat design makes extensive use of commercial-off-the-shelf ...
5
votes
1answer
748 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, ...
193
votes
6answers
19k views

Can I borrow a lunar rover?

According to Wikipedia there are 3 LRVs sitting on the moon, in very well defined locations. Would China, or whomever gets to the moon with a person next, be able to get in and drive around in an LRV ...
47
votes
8answers
12k views

What would be the (most difficult) challenge to make a 10,000 year satellite?

Update: Bezos' recent Tweeted update on the 10,000 year clock. Also see The Verge's Construction begins on Jeff Bezos’ $42 million 10,000-year clock The discussions associated with the question Can ...
14
votes
2answers
10k views

How can I plot a satellite's orbit in 3D from a TLE using Python and Skyfield?

I have obtained a Two Line Element (TLE) of a satellite in Earth orbit from Celestrak at https://www.celestrak.com/NORAD/elements/ and I would like to use it to calculate an orbit. How can I ...
21
votes
3answers
22k views

Puncturing space suit during EVA. What would happen?

What would happen, if the space suit of a spacewalking crew was punctured during the extravehicular activity (EVA)? What are the chances of this happening? Has this already happened to anyone in the ...
15
votes
1answer
2k views

How strong and “hot” is the wind on the payload after the fairing is deployed at ~110km?

In the question What makes 21st century fairings so valuable that they'd potentially be recovered and re-used? I said: 21st century fairings are much more than passive rooftop boxes to "keep the ...
6
votes
2answers
862 views

Getting state vectors from JPL Horizons ephemerides

I'm simulating the Sun-Earth-Moon system by numerical integration of equation of motion. I've confused a little bit in JPL Horizons ephemerides. Could anyone explain (if possible, on pictures), how ...
22
votes
2answers
2k views

Going from LEO to lunar using only low-thrust ion propulsion - can it be done?

@SF.'s question What are the parameters of the new Iodine electrical rocket engine developed by RSC Energia? links to the short RT article 'Ten times cheaper': Russian space company testing iodine ...
11
votes
2answers
2k views

Do antennae on the ISS have to constantly move to maintain data links?

In this question and answer pair I see that the ISS can maintain data links to earth through direct access to ground stations as well as through the TDRSS geostationary satellite network. What kind ...
8
votes
2answers
949 views

What are these very large, square panels on Inmarsat 5?

Question: What are these very large square panels on Inmarsat 5's? They seem to each have an extremely reflective mirror-like flat/smooth tiled-appearing side, and a nearly black side with a lot of ...
11
votes
5answers
792 views

Why doesn't thermal radio emission from a DSN “hot dish” completely swamp the benefits of a cold LNA?

The 70 meter DSN dishes are often used to receive the weakest signals, and so their receiver LNAs have cryogenic front-ends in an assembly that also contains a LHe refrigerator and vacuum system. If I ...
9
votes
1answer
847 views

Have there been any documented mini-moons since 2006 RH120?

The conference call with Bill Bottke (MP3 plus other documents) about "minimoons" presents an alternative to Asteroid Redirect first got me interested in orbital mechanics. The idea is that there are ...
6
votes
1answer
1k views

Why would sub-cooled LOX tanks need to “topped-off” until the last minute or so?

Here is my understanding, let me know if I've got it right or wrong: Until recently, most cryogenic propellants were at or close to their boiling points. Each unit of heat leaking into the tank would ...
108
votes
13answers
53k views

What are the choices today for orbital mechanics simulation software?

I used to be familiar with the various choices out there for orbital mechanics simulation software. Alas, those days are gone. What are the choices today, preferably sorted by platform? This ...

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