Questions tagged [propulsion]

Systems for propelling a spacecraft from one place to another, such as rockets.

Filter by
Sorted by
Tagged with
1
vote
0answers
64 views

Technological challenges to sending a high altitude balloon to space and orbit from 50 km?

Below At what altitude would I have to go in a lighter than air balloon to be above all wind and just have the earth rotate underneath me? there is a comment: If you want to be above all winds, you ...
-1
votes
1answer
167 views

Could affixed variable spaced magnets propel a spacecraft? [closed]

What if the craft itself had a magnet at the rear, with an equally sized magnet that you could either bring towards the craft to propel forward ....or controlling it away from the ships magnet to ...
32
votes
4answers
4k views

Is warp drive a legitimate avenue of scientific investigation?

I've been reading a number of online "pop-sci" articles on the subject of "warp drive" - derived from work done initially by Alcubierre. Some of the most recent articles say that there are ...
66
votes
17answers
20k views

Why is using a space elevator cheaper than rocket power?

Why is rocket power so much less efficient? In both cases you want to lift a given weight a certain height. What does climbing a tether give you that you don't have when using rockets? Wouldn't a ...
22
votes
6answers
6k views

Why are Ion Thrusters so energy hungry?

Ion thrusters need a lot of energy. But I don't understand why. So, one thing I understand is that it takes a lot of energy to achieve a high exhaust velocity (since kinetic energy is proportional to ...
19
votes
7answers
11k views

Can ion thrusters be scaled up?

All ion thrusters are quite small. Having read through the more approachable information about them, as they use physics pretty beyond me, I don't understand what it is about them that makes it ...
18
votes
6answers
5k views

Methods for propulsion other than rockets for leaving Earth's atmosphere?

Due to the large amount of energy required, the standard method for leaving the Earth's atmosphere is rocket propulsion. Is there any other methods in development that don't involve rockets? E.g. ...
10
votes
7answers
4k views

Is it possible to get a spacecraft into earth orbit using Linear Eddy Current Braking on an orbital runway?

The "Space Runway" [I have slightly edited this to clarify some issues that have been raised] Luke Parrish mentioned an unusual and novel space launch method to me. The idea is to get a spacecraft ...
9
votes
3answers
2k views

Troubleshooting a DIY Ion Thruster

Been following a Make-Magazine article on how to make your own ion thruster: https://makezine.com/projects/ionic-thruster/ Went through the tutorial step by step, not seeming to get any thrust out of ...
19
votes
4answers
12k views

How much does it cost to fill an ion thuster with Xenon for a spacecraft propulsion system?

Ion engines are touted as a great source of propulsion for high deltaV missions that can afford an ample power supply and need low thrust maneuvers; and they are great. But I'd like to know how much ...
13
votes
1answer
485 views

How much delta-v can be achieved by venting the ISS atmosphere?

A sort-of follow-up to What do the astronauts do whilst the air-lock cycles? The ISS fact-sheet writes to say Pressurized Volume: 32,333 cubic feet (916 cubic meters) Elsewhere on the stack are ...
11
votes
1answer
2k views

Could a harpoon-like gun be used by an astronaut to stop drifting away from a ship?

I saw the movie Gravity. Spoiler alert, hover with your mouse over the yellow bar below to reveal a part of the movie's plot: Why can't they have a gun kind-of thing with a string/rope? One end of ...
11
votes
4answers
4k views

Laser propulsion possible?

Is it possible to get an impulse, if you shoot at a solar sails with lasers mounted on the spaceship? If so, why doesn't a laser create a force, if it fires/releases a photon? Is the impulse ...
10
votes
1answer
451 views

Why did the MarCO space probes use fire extinguishant as their propellant?

In many news articles, it's mentioned that the MarCO spacecraft, launched with InSight, used fire extinguishant as the propellant for its cold gas thrusters. I originally assumed that this was ...
7
votes
2answers
762 views

Is this description of the “dipole drive” and how it would work physically correct?

Comments in chat have noted the recent post in the Centauri Dreams blog titled The Dipole Drive: A New Concept for Space Propulsion. In contrast to the single positively charged screen employed by ...
6
votes
1answer
161 views

Hows does “Glenn Research Center's sapphire refractive secondary concentrator” work?

Clicking through NASA.spinoff.gov I came to the page for spinnoff 2001 Glenn Research Center and found this: Glenn Research Center's sapphire refractive secondary concentrator will be used with ...
30
votes
3answers
7k views

Has in-space refueling been done?

Before the Apollo program committed to the lunar orbit rendezvous mode, one of the Earth orbit rendezvous proposals involved launching two Saturn Vs, one with the Apollo spacecraft and large lunar ...
16
votes
1answer
480 views

How far have autophage rockets been developed?

Ars Technica reports on a May 24 phys.org press release/precis on a University of Glasgow paper in Journal of Spacecraft of Rockets about a solid rocket intended to consume itself during use rather ...
16
votes
1answer
794 views

How important is plume impingement in rendezvous operations?

When performing space rendezvous operations close to the target vehicle (0-5 m relative distance), pursuer thruster escape nozzle gases can hit the target if firings are done in the direction of ...
9
votes
3answers
2k views

Why do lower molar mass rocket exhaust products give higher specific impulse?

I tried to work this out. My thinking is as follows. If the same amount of energy is given to a low mass particle and a high mass particle, the low mass particle is faster. A particle with a mass of 1 ...
8
votes
1answer
551 views

Are ion thruster trajectories classified as brachistochrones?

Usually, when performing trajectory optimizations for chemical rockets, the limiting factor is the $\Delta v$ budget. That means velocity change is the optimization factor, with things like transfer ...
8
votes
1answer
350 views

STS: How much thrust did the nominal post-MECO LOX dump produce?

Following up to some questions asked in comments to the answer to this question: With pressure-fed engines, is any measurable thrust generated by venting the pressurant out the engine bell after ...
6
votes
1answer
632 views

How much time does it take to circularize a GTO orbit using ion propulsion?

SpaceX launched two GEO comsats, and is about to launch two more, that use all-electric ion propulsion. Now, I'm wondering, how much time would it take to actually make a satellite like that ...
5
votes
6answers
790 views

Can solid rockets be used for flexible burn time by jettisoning them?

Solid rockets have some advantages such as high thrust (good for using the Oberth effect), storability and reliability. The main problem is that they fire all their fuel once in one set way. But ...
5
votes
2answers
2k views

How does the Sabre engine's pre-cooler achieve such high performance?

The BBC News article Rolls-Royce and Boeing invest in UK space engine about Reaction Engines Limited (REL) and its Sabre engine states REL is developing what it calls the Sabre engine. This power ...
4
votes
1answer
798 views

What was the Apollo service module propellant used for on the LEO missions?

The Apollo service module carried a lot of propellant for performing the following tasks on a Moon mission: Mid-course correction manoeuvres to and from the Moon. Braking the entire CSM/LM stack into ...
1
vote
1answer
271 views

Could a CubeSat be propelled by this low-tech electromagnetic propulsion system?

I have come up with a conceptual idea for a low-tech electromagnetic propulsion system for a CubeSat, and I would like to know if it would create (on a theoretical basis) a net force strong enough to ...
1
vote
1answer
169 views

For a DAWN-like solar-electric deep space mission, would using propellant particles much heavier than xenon atoms be beneficial?

For deep space missions using ion propulsion that are power-limited, this answer explains that a large mass/charge ratio ($m/q$) species is desirable. The solar-electric propulsion system used by the ...
0
votes
1answer
148 views

Ambient pressure for vaccum nozzle design

How do I find out the ambient pressure for designing a vaccum rocket engine? I am using the propellant combustion charts from the braeunig website. But I cannot figure out the ambient pressure for ...
11
votes
2answers
3k views

Rocket Engine Plumbing: Still Confused about the Preburner

I know I'm not the only one who has this question, but I still have trouble wrapping my head around how a rocket engine preburner works. I understand that the preburner is what gets the rocket's ...
9
votes
1answer
259 views

Would it be cheaper to go to Mars if the empty transit vehicle is slowly accelerated before the passengers board?

Would it reduce the cost/time to go to Mars with people if the transit vehicle was accelerated using less expensive means (i.e. ion engine and/or gravity assists), and the people got took a small ...
9
votes
3answers
1k views

Do any realistic rocket systems use different substances for propellant and fuel?

In his Edge.org Annual Question response, Progress in Rocketry, George Dyson exults in the success of Blue Origin and SpaceX in landing their rockets after pushing them past the Kármán line, and then ...
8
votes
1answer
331 views

What are the challenge to use atmosphere as a propellant for super low altitude (180-260 km) satellites?

JAXA is planning to launch SLATS (Super Low Altitude Test Satellites). Theses will orbit for > 2 years using ion propulsion to counteract the substantial drag at the 180-260km high altitude. They ...
7
votes
3answers
4k views

Ion Thruster Thrust Calculation Problem

Trying to calculate the impulse of a little ion thruster I'm putting together. An old version of it can be found here, I'll be polarizing the AC current and putting in copper nails on the next ...
7
votes
1answer
845 views

Propellant Settling for RCS Thrusters

The recent discussions about the SpaceX SuperDraco thrusters got me to thinking: When you restart a turbopump rocket engine in zero-g, you have to perform a "settling" or "ullage" burn to get the ...
5
votes
2answers
2k views

What are some notable cold gas thruster propellants, and why?

Cold gas thrusters are a very simple and reliable form of thruster that operate only by spraying a compressed gas, without any chemical reaction. What are the most common, performant, or otherwise ...
4
votes
1answer
165 views

Is there any possible reason to direct the electron gun specifically towards the ion trail behind an ion thruster?

This answer to Neutralization of ions in the ion thruster quotes the introduction to Wikipedia's Ion thruster: Temporarily stored electrons are finally reinjected by a neutralizer in the cloud of ...
4
votes
1answer
1k views

Advantage of full-flow staged combustion vs conventional staged combustion engine

Referring to the question in this thread. What is the advantage of full-flow staged combustion (FFSC) vs conventional staged combustion rocket engine? In FFSC we feed the full volume of fuel and ...
3
votes
3answers
406 views

At what size does a bigger solar sail stop increasing your acceleration?

Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce? Can a solar sail be added to an ion engine and work better?
3
votes
1answer
149 views

How can an electric sail be used for deorbiting considering that it doesn't work inside the magnetosphere?

An electric sail harnesses the solar wind for propulsion. Inside the magnetosphere of Earth, the solar wind does not reach. Yet the Aalto-1 satellite intends to deorbit using an electric sail. How ...
3
votes
1answer
143 views

Why might krypton have a lower utilization fraction than xenon for ion propulsion, and what can be done to improve it?

A comment below Why will Starlink satellites use krypton instead of xenon for electric propulsion? links to the 2011 preprint A Performance Comparison of Xenon and KryptonPropellant on an SPT-100 Hall ...
3
votes
2answers
3k views

There are better oxidizer than oxygen?

Liquid oxygen is cheap to obtain and available, but are there better oxidizers to achieve bigger thrust with JP1?
1
vote
0answers
56 views

How does a “hybrid orbital raising system” based on R-4D (N2O4/MMH) + SPT-100 (Hall effect) work exactly? (Intelsat 38 & 39)

Astronatix's Intelsat 39 lists the two engines SPT-100 Stechkin 1.35 kW Hall thruster. R-4D Marquardt N2O4/MMH rocket engine. 490 N. Question: Why is this combination on Intelsat 39 called "hybrid" ...
1
vote
2answers
269 views

Which propelling device would be the most efficient for a space elevator?

There are many types of propulsion from electric turbine engines to steam powered catapults once used on aircraft carriers. Which of the many types of propulsion would be the most efficient in getting ...
-5
votes
3answers
335 views

Never reducing propellant for space propulsion [closed]

In this sketch there is a gun system as a propellant chamber and we are using iron balls as a propellant. An electromagnet is attached on the other side of this engine .When we fire these Iron ...
14
votes
2answers
17k views

Efficient types of nozzles used in rockets

Is there any other type of nozzle other than common convergent-divergent nozzle (see picture below) which is used in many rockets?             ...
17
votes
2answers
2k views

Why is the “impossible” space drive impossible?

So apparently NASA just built an impossible propulsion device: Sawyer's engine is extremely light and simple. It provides a thrust by "bouncing microwaves around in a closed container." The ...
6
votes
3answers
4k views

Would a 'small' rocket like this reach space?

I want to build a solid fuelled rocket (I was thinking 3 stage with 2 boosters) that'd launch a micro-satellite (cubesat size) into space but first I want to try reach space (100km) with no payload. ...
42
votes
1answer
7k views

Do booster stages run out of fuel, or are they purposefully shut off?

When an expendable booster rocket stage nears the end of its burn, does the guidance computer shut the engine(s) off at a certain velocity/altitude for the mission, or does the stage completely ...
19
votes
6answers
7k views

What limits the speed of space probes currently?

...other than budget, obviously. Our computers nowadays are good enough that we should be capable of sending a probe to a neighbor star system and back, and get some pretty good analysis reports. We ...