Questions tagged [design-alternative]

Questions about alternative designs the asker has thought of, such as "why was X built this way and not this way"

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33
votes
6answers
10k views

Why aren't air breathing engines used as small first stages?

I am wondering why we don't use jet engines as first stages. Most small rockets, like the Electron, can lift off with a small thrust. In the Electron's case, 192 kN. Why can't we replace the 9 ...
28
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8answers
7k views

Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?

I am wondering if any space agency has ever considered using a grinding machine as a propulsion system for an interplanetary spacecraft. This system would not be used to lift the spacecraft off of a ...
23
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3answers
5k views

Why isn't SpaceX constructing the Super Heavy launch mount on top of the water?

With SpaceX creating their launch facility in Boca Chica Texas, right next to the water, why would they bother building a huge launch pad to withstand the blast, as opposed to building it on top of ...
23
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9answers
10k views

If someone built a vacuum tunnel through the atmosphere, could you have an orbit with a sea level perigee?

This is something I've been thinking about for a while now. My initial estimates for the structure were based on people's estimates for an O'Neil cylinder, but assuming you can make the structure a ...
21
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4answers
3k views

What would be necessary in order for us to achieve a single stage to orbit, reusable rocket?

I have read articles and seen videos explaining why an SSTO (Single Stage To Orbit) rocket* is not possible. But I was wondering... What would be required to achieve this? Answers can be literally ...
18
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6answers
9k views

Why can't they just drop a solar winch down from a shuttle and have planes fly up and clip things on?

Why can't they just drop a solar winch down from a shuttle and have planes fly up and clip things on? I know of the idea to have a space lift but the cable necessary is too expensive. Why can't we ...
18
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6answers
4k views

Would a higher air pressure on the ISS or elsewhere make it easier to “swim” in microgravity?

What if the atmospheric pressure onboard the ISS was 5 atm, 5 times the pressure on Earth and currently on the ISS, while maintaining the breathable oxygen level, e.g. if the additional atmosphere ...
17
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3answers
2k views

Could a spacecraft be made out of wood?

Could a spacecraft use organic materials, like wood or bone or shell or other tissues, as an interface to the vacuum and radiation of space? Would wood outgas and crack up in space? I wonder if life ...
14
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2answers
1k views

Could one actually make a grain silo rocket?

Watching the recent SpaceX Starship tests got me to thinking: Could you actually make a rocket using grain as the propellant? Image from https://www.teslarati.com/spacex-starship-sn5-second-hop-plans/...
13
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7answers
8k views

Could a space colony 1g from the sun work?

Let me break down my thoughts and I have no science background so let me know if this could even be possible. Have the colony on an object like a big asteroid or a similar man made construct. Have ...
12
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3answers
4k views

Rocket flywheel instead of battery/generator (crazy idea)?

The Electron rocket is launched using a battery instead of generator... I saw some video about research into using flywheels for energy grid buffer storage, I think that they could reach higher ...
12
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2answers
3k views

Can a rocket refuel on Mars from water?

Can a rocket run only on hydrogen and oxygen? Could a rocket, rover, and electrolysis machine be sent to either of Mars' poles to excavate ice to make hydrogen and oxygen to refuel an unmanned rocket? ...
10
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1answer
605 views

Does a high staging number have diminishing returns? Is there a way to address that mathematically?

I was reading this question: Help me understand what Farside, a ten "stage" rockoon looked like? How was it configured? Comments link to Highest stage counts in actual launchers? but here ...
10
votes
1answer
727 views

What's the final word; does the EmDrive drive work or not?

I'd like to know the final verdict on the EmDrive (or EM Drive); does it work or not? Some say yes, others say no, some say the measured effect was not propulsion, but just the energy radiated by the ...
9
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4answers
4k views

What are the biggest challenges for high altitude rail-gun launch systems?

Use a maglev railgun for initial acceleration - in a new, hyperbolic tunnel facing eastward - this exits from the burrowed -undergrade- track to Equadors' Mt. Chimborazo peak - (a mountaintop both 6 ...
9
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6answers
2k views

Using water as a high density storable hydro-lox propellant

Hydro/lox is an excellent fuel choice and has been used in many engine/rockets with high ISP requirements, however, the two biggest drawbacks of the propellant are its density and boil-off. Could this ...
9
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3answers
708 views

What are the deal-breakers with a preheated Hydrogen gas tank orbital rocket?

Consider this thought process: In selecting the propellant for a reaction engine, lower atomic mass is better because equipment is largely temperature limited, and lighter gas will get higher ...
7
votes
5answers
940 views

Earth Launch System with Water Propellant

Water based thrusters have been proposed (and possibly tested by now) for use in satellites and other in-space vehicles - see this NASA article. The idea is to perform electrolysis on the water to ...
7
votes
5answers
1k views

Could moon ice be used to fuel a steam powered jetpack for EVA in space or high altitude exploration on the moon?

For long term moon operations, would it be practical to have a jetpack that used steam as a source for EVA on the moon surface and above it in orbit? I imagine a scenario where lunar ice deposits ...
7
votes
1answer
394 views

What would be the challenges for a 50 km long tether to the surface of Venus to get recurrent surface samples there?

Basalt fiber would be an excellent material for a tether in the atmosphere of Venus because it could withstand both the acidity and the high temperature near the surface there. From this answer about ...
6
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2answers
1k views

Can a VASIMR Plasma engine be used to launch a rocket?

When I was in primary school, I spent countless hours designing spaceships that probably wouldn’t work. It’s only now that I’ve stumbled across some of the old drawings and actually thought if it ...
6
votes
1answer
620 views

Is a Lofstrom loop realistic

Is a Lofstrom loop (also known as launch loop) realistic? The general idea behind a Lofstrom loop is a large structure intended for easier access to space, held up by active support (think rotating ...
6
votes
3answers
208 views

Creating your own artificial gravity by running. (Part 1 - the basic idea)

The main motivation for artificial gravity is the astronauts' health Usually artificial gravity is supposed to work by rotating the spacecraft. See diagram A. Wouldn't it be much simpler to simply ...
6
votes
2answers
330 views

What are the challenges in recovering Falcon 9's second stage this way?

The Falcon 9's second stage is currently disposed of each flight. I know there have been some concepts by SpaceX on making it reusable, but evidently they have not yet done so. From my understanding, ...
6
votes
1answer
663 views

Why can’t cryogenic propellants be storable, at least on the ground, via refrigeration?

Cryogenic fuels (liquid hydrogen, liquid methane)1 and oxidisers (liquid oxygen)2 are the rocket propellants of choice where raw performance is the overriding concern, due to the very high performance ...
6
votes
1answer
165 views

Is methylsilane CH6Si ever considered as fuel in rocketary?

Methylsilane CH6Si seems to have some useful properties for rocket fuel: High hydrogen content, 6 atoms per molecule, 13% of overall mass, High combustion energy, -2612KJ/mol or 56.8 MJ/kg (better ...
6
votes
0answers
165 views

Would this Starship design alternative be viable?

Considering Starship atmospheric entry, belly dive and "bellyflop", latest iteration displays four aerodynamic surfaces, two aft fins and two carard fins. Soon will this configuration be put ...
6
votes
0answers
134 views

If Elon Musk wanted to bring back some Martian soil, would US permission be required?

A scenario occurred to me recently where the Chinese space program decided to go all-in on Mars sample return, and their schedule was such that it would happen before the NASA/ESA mission was ...
5
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3answers
2k views

Terraforming Mars using a combination of aerogel and GM microbes?

Silica aerogel is a technology that's been proposed for colonisation of Mars. Basically, it's a very good insulator that's also transparent to visible light, and could be used to warm up parts of Mars ...
5
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4answers
2k views

Could a steam engine work on the moon? [closed]

Recently, there was a thread on Hacker News about building a nuclear power plant on the moon. Humans being what they are, I could imagine some dark outcomes. Instead could we build a steam engine on ...
5
votes
2answers
1k views

Can you Hoverslam without going vertical?

Problem of the day, that pesky Starship Hoverslam. Imagining a crazy (childish) contest to see who could flip at the lowest altitude and brake to 0 rate of descent and land, it was (hilariously) ...
5
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3answers
324 views

Fast spining solar cells to clear Martian dust possible?

I've seen a fast spinning glass wheel used in front of a camera to clear away water, dust or ice. Could Solar panels be made circular and spin to clear dust off of them in the same way may? As ...
5
votes
3answers
644 views

Two 1000 kg gold spheres orbit their CM in near-contact, great way to measure G or limited by spaceflight issues?

The hypothetical, non-existent crowdfunding site go-launch-me is so confident, they are offering a two-for-one special. For a limited time, if your project is funded they will foot the bill for a 2nd ...
5
votes
3answers
451 views

If specific impulse is directly related to exhaust velocity, would a ion post-accelerator improve the Isp of a propulsion system?

I understand that ion- and hall thrusters resemble a particle accelerator, and that led me to wonder if a post-accelerator (particle accelerator) used to boost the velocity of the ions would improve ...
5
votes
1answer
284 views

Is there some fundamental limitation that would prevent steam-powered rockets from reaching space?

According to the Discovery Channel (see CNN article below) the latest attempt to use compressed steam propulsion to get to 5000 feet ended in tragedy. It's not yet clear the altitude it reached, ...
5
votes
3answers
515 views

Could Earth's electric grid be used to power rocket launches via cable?

If our regular huge power plants on the ground could be used to power part of a rocket launch, launch mass would be smaller since fuel would not have to be carried on board. I wonder what are the main ...
5
votes
1answer
147 views

Proposed spacecraft propulsion with particle accelerator

With the new particle acceleration technology of plasma accelerator, electrons or protons can be accelerated to relativistic speed in a device much smaller than current Linac (According to wikipedia, ...
5
votes
1answer
104 views

Water ice as dummy/filler payload to orbit

When I'm rich, and my reusable orbital launch program is well under way, I will be performing many orbital test-launches and paid satellite deployments. Once I've knocked out the bugs and optimized my ...
5
votes
1answer
406 views

How much does launch costs have to come down to make chemical fuel deep space probes feasible?

Considering that NASA have been running short of plutonium for their RTGs, it makes sense to consider alternatives. For the inner solar system up to Jupiter, solar cells have been demonstrated on ...
5
votes
3answers
128 views

Can we generate electricity from Martian sandstorms? If so can it be used for powering colonies?

Rapidly varying electric fields inside dust storms have been observed and studied for years. The winds in the strongest Martian storms reach 60 miles per hour.
5
votes
1answer
273 views

Could a fairing vacuum protect the payload from acoustic loads?

This is a weirder question, but here it goes: During launch, a payload (let's say a satellite) undergoes intense shaking and acoustic loads. This is known from the launcher parameters and the ...
5
votes
1answer
138 views

Semi-feasible alternates to silicon electronics for a Von Neumann Probe?

Disclaimer: this is a modified cross-post of my post on the Worldbuilding SE site, adapted to better fit the Space Exploration community. Some background A Von Neumann Probe (VNP) is a sci-fi probe ...
5
votes
1answer
214 views

What might be a viable avenue of propulsion research in aiming for mission delta-V north of 100 km/s?

This question was inspired by some comments of mine I left on an answer here: Is it better to develop more powerful rockets instead of seeking and developing new technologies? and thus in turn both ...
5
votes
1answer
320 views

Is there anything fundamentally wrong with 'autogenous expander cycle`?

This question is a spinoff from here. To set the context, here is my understanding of the expander cycle: Closed expander cycle is very efficient, perhaps more efficient than staged combustion cycle....
5
votes
0answers
19 views

Using electrodynamic tethers for countering precession?

One of the potential uses of electrodynamic tethers for satellites is generating thrust without needing to expend reaction mass. Could this potentially be used to counteract precession, allowing ...
5
votes
0answers
59 views

“Hybrid” statite design for a Dyson bubble?

One proposed design for a Dyson sphere is the Dyson bubble, which consists of statites (satellites that use light pressure to counteract gravity). In this design, the statites remain stationary ...
5
votes
1answer
229 views

Could a solar sail composed of smart glass stay near the L1 point of Venus?

From answers to this question i've learned that the Lagrangian L$_1$ point of Venus is not stable, despite the almost circular orbit of the planet and the fact that it has no moon. Nevertheless would ...
4
votes
2answers
673 views

Compressed gas thruster for an orbital launch vehicle?

Is it possible for a compressed gas thruster to be used to launch a spacecraft into orbit? Let's say, it's already moving at 250MPH(111.7 meters/second) relative to the planets surface. Planets ...
4
votes
1answer
442 views

What was the point of the Redstone rocket when there was the X-15 rocketplane?

Just a curiousity question, so don't get me wrong for I very much admire and have high respect towards the entire Mercury project, Alan Shepard (the first American in space, a national hero) and Gus ...
4
votes
1answer
404 views

Could the Dream Chaser or Space Shuttle fly/have flown to the Moon with boosters on the orbiter's side?

In the 1998 movie Armageddon the crews use Space Shuttles which have boosters also on the orbiters' sides (two boosters per orbiter) in order to get to the Moon and to the asteroid. Upon descent onto ...