All Questions

30
votes
4answers
12k 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 ...
47
votes
4answers
5k views

How much bigger could Earth be, before rockets would'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. Question: "How much bigger ...
5
votes
2answers
639 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 ...
10
votes
3answers
1k 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 ...
26
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 ...
9
votes
3answers
2k 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 ...
21
votes
4answers
7k 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 ...
27
votes
3answers
31k 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 ...
28
votes
1answer
56k 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 ...
97
votes
11answers
41k 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 ...
20
votes
3answers
17k 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 ...
25
votes
2answers
6k 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 ...
5
votes
1answer
2k 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 ...
41
votes
11answers
34k 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-...
10
votes
2answers
856 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) ...
25
votes
3answers
3k 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, ...
3
votes
0answers
283 views

“Deep space” corrections in SGP4; how does it 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 ...
9
votes
1answer
1k 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 ...
35
votes
3answers
79k views

How fast will 1g get you there?

If you have the energy for a constant 1G thrust, how long would it take to get to the planets in our solar system? How long for the 5 nearest solar systems? Assuming turn over and decelerate at ...
48
votes
8answers
11k 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 ...
42
votes
2answers
9k views

Why is gold used in space technology to protection from heat radiation?

AFAIK, NASA and others are using mainly gold to protect surface from heat radiation. But, as we can see with our own eyes, chrome or silver had probably a much better albedo, because they are white, ...
26
votes
7answers
9k 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 ...
37
votes
4answers
4k views

Are there any safety procedures in place on the ISS in case of puncture?

The ISS is a huge (relatively) satellite which, according to NASA, is longer than a football field. I am curious about what would happen if the station's skin was punctured - perhaps by a careless ...
42
votes
2answers
33k 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. ...
16
votes
5answers
16k views

Can magnets be used to launch spacecraft?

I assume there is some reason we don't use magnets to launch off Earth. Are they not strong enough? Isn't magnetic force technically stronger than gravity?? Would either of these work: A tube tunnel ...
9
votes
2answers
1k 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 ...
29
votes
4answers
6k views

Is it possible to track an object as small as the Tesla Roadster around the Solar System

I have heard that we will soon lose track of the Tesla Roadster launched with the Falcon Heavy test launch. Yet, we know where Voyager is out beyond the Solar System and we followed other satellites ...
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. ...
17
votes
4answers
58k views

How far do you have to be from Earth to be “in space”?

According to a recent news article a group of USC students are attempting to launch a rocket "in to space" with a planned height of 62 miles. Making them "the first group of students to successfully ...
8
votes
2answers
2k 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 ...
8
votes
1answer
5k 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 ...
22
votes
8answers
4k views

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

Not a trick question, but a real puzzler - which spacecraft or spacecrafts incorporated real wooden structural elements?
7
votes
1answer
1k views

What is the current record for the farthest detection of a “dead” spacecraft?

In order to better defend my position that trying to track Juno from Earth once it can no longer transmit would be Quixotic, I'd like to ask what the current record is for the farthest detection from ...
58
votes
8answers
31k views

Why would SpaceX not use parachutes for the final descent of the first stage?

According to what I've read, SpaceX tried to use parachutes to recover the first stage of the Falcon 9, but it did not survive reentry. Now they plan to use 2 separate rocket burns to land: Reentry ...
43
votes
7answers
41k views

Can I see the ISS from the surface with the naked eye?

Can I see the International Space Station (ISS) from the surface with the naked eye? If yes, how can I determine that it really is the ISS?
46
votes
7answers
66k views

How would it be possible to kick start Mars's magnetic field?

Jumping from this question about terraforming Mars, how would one mitigate the main obstacle, namely Mars's lack of a magnetic field? Are there any hypothetical processes that might restart Mars's ...
28
votes
3answers
26k 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 ...
23
votes
3answers
5k views

How can I intuitively understand gravity assists?

For example: How should a spacecraft pass the Moon to reach escape velocity from Earth? How should it pass Venus for a slingshot towards Jupiter orbit? Conversely, to descend Venus to Mercury? Is ...
47
votes
4answers
39k views

Why not build Saturn V's again?

Why is the US developing a new rocket and spacecraft as opposed to building the Saturn V and Apollo stacks again? The SLS / Orion development programs certainly can't cost less than the unit cost of ...
35
votes
5answers
10k views

Why aren't all satellite-carrying rockets launched from airplanes?

There are several significant advantages to air launching a satellite-carrying rocket: save fuel/propellant as a horizontal take-off is more energy efficient fully mobile platform allowing the launch ...
14
votes
2answers
7k views

What is the math behind Magnetorquers?

I'm trying to better understand the mathematics behind how torque rods work. I know that even if you have 3 axis of magnetic torquers, in effect there is only 2 axis of control, and I'm trying to ...
26
votes
3answers
2k views

Are there any safe-to-launch alternatives to RTG's for outer solar system exploration?

In the past two decades, NASA has launched at least three missions that use RTG's: Cassini Mars Science Laboratory New Horizons Those launches include plutonium, which is a reason for some to oppose ...
15
votes
2answers
17k views

Launch Accelerations: Values, history

This topic: What G-forces do different launchers cause? indicates that current satellite launchers are limiting peak acceleration to about 4g. I'm pretty sure the STS (Shuttle) did the same. My ...
5
votes
1answer
168 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 ...
16
votes
4answers
3k views

Radiation shielding magnetic or mass, which is more efficient?

As I understand it; being away from earth subjects you to significant health risks from radiation. On Earth most of this risk is deflected by Earth's magnetic field. I did not find a reference but ...
6
votes
2answers
644 views

The Orbital Mass Accelerator Engine Theory

Can 2 satellites equal in weight traveling on the same orbital path in the opposite directions intersect and propel each other to gain altitude in orbit? Can orbital perturbation be negated during ...
14
votes
3answers
2k views

Space debris half life

In case there will be zero space launches starting at some point in time. How long will it take for the space debris mass in LEO to be halved?
18
votes
3answers
1k 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 ...
4
votes
2answers
1k 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 ...

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