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Would it be possible for a spaceship of some sort to descend from space and through the atmosphere of an Earth-like planet, not land, then turn around and head back into space? In other words, could it move freely between space and the Earth-like planet's atmosphere without the inconvenience of having to land?

As far as I'm aware, no such technology as would be required for such a maneuver has been invented by humans. So I'm wondering: if this is possible at all, exactly what technology would be required?

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    $\begingroup$ What is the purpose of entering the atmosphere? $\endgroup$ – sphennings Apr 3 '17 at 16:44
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    $\begingroup$ Somewhat related: Would it be possible to skip an asteroid off of a planet's atmosphere? $\endgroup$ – DaaaahWhoosh Apr 3 '17 at 17:17
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    $\begingroup$ Oh I agree, just trying to get a refinement on what you want by giving examples of things. I think the point of orientation requires the ship your looking for to be in Orbit, lets call it Space. It enters Earth's Atmosphere (what characteristics do you want it to be able to do) then can leave Earth's Atmosphere without landing. I can not see why this can't be done. Skylons SABRE Engine may very well work to do what you want, it would be fuel capacity dependent. en.wikipedia.org/wiki/SABRE_(rocket_engine) $\endgroup$ – Enigma Maitreya Apr 3 '17 at 17:20
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    $\begingroup$ Can I suggest you to play Kerbal Space Program? Orbital mechanics are ludicrously counter-intuitive. I should know better, and they still kept getting me by surprise until I played Kerbal Space Program. Having developed some intuition, after playing KSP (including successfully, in game obviously, spaceplane designs) I can tell you that what you want is actually more hassle than landing and taking off again. $\endgroup$ – M i ech Apr 3 '17 at 17:39
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    $\begingroup$ While I'm thrilled to score another accepted answer, it's generally a good idea to wait at least a day, preferably few before deciding. Users in different time zones, and thus sleeping or working didn't even have a chance to take a shot at answer. $\endgroup$ – M i ech Apr 3 '17 at 20:49
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Can a spaceship enter atmosphere and exit without landing?

Sure it can. It's called...

Aerobraking

This technique is actually used to make re-entry safer in some circumstances. Basically, entering deep atmosphere at too high a speed is rather destructive, as the heat becomes unmanageable. If an object returns from afar and its orbital velocity is too high, it can enter the outer layers of the atmosphere to deliberately experience air drag and lose speed. The object will lose some speed and exit the atmosphere again, at lower velocity. This can be used to shed velocity for safe entry.

It can also be used to "capture" the object. Then it's called...

Aerocapture

Basically, it's a case where aerobreaking is used to reduce the velocity enough to turn a flyby at hyperbolic trajectory into capturing in an elliptic orbit.

However, this is not what you want.

What you want can't be done with our technology, and it doesn't seem like we are getting the required tech any time soon.

If you want a flyby near the surface, then it's not possible with present technology. You pretty much need functional spaceplanes to do it. Air at the surface is thick and causes a lot of drag; if you reach the surface too fast, you will burn. To get anywhere near the surface, you need to lose enough velocity to perform atmospheric flight. Orbital speed at LEO (Low Earth Orbit) is about 7800 m/s. For comparison, the SR-71 Blackbird barely reached 1000 m/s and had very serious heating concerns.

Basically, to reach the surface with orbital velocities, you need incredibly resistant heatshields and incredibly powerful engines. Your only other option is to shed so much velocity that you can treat the return to orbit as starting from the ground.

It's actually MORE of a hassle to reach the surface at high velocity than it is to land and take off again.

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    $\begingroup$ Have you considered this arstechnica.com/science/2016/04/… - This changes your assumption that the speed must be reduced by friction. IF there is a fully fueled "Space Plane" that can perform this maneuver and it has been performed a number of times by SpaceX, yes at lower speeds but there is no evidence this does not scale, it just fuel (easy for me to say that). Skylons Space Plane clearly is not a Build it once fly it to LEO and destroy it. en.wikipedia.org/wiki/Skylon_(spacecraft). $\endgroup$ – Enigma Maitreya Apr 3 '17 at 17:47
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    $\begingroup$ @EnigmaMaitreya Powered landing is a massive logistical headache. Every gram of reaction mass needs to be brought on the ship, which means reaction mass had to be spent on bringing it. Growth on reaction mass requirements is literally exponential (Tsiolkovsky equation). That's why aerobreaking is always preferable, it needs no reaction mass and heat shielding weights less than reaction mass for powered re-entry. Basically, powered re-entry is the LEAST efficient velocity shedding method possible. Article spoke of Mars for good reason. Mars has insufficient atmo to shed velocity for landing. $\endgroup$ – M i ech Apr 3 '17 at 18:01
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    $\begingroup$ "Every gram of reaction mass needs to be brought on the ship, which means reaction mass had to be spent on bringing it" but that has all changed. Fuel Stations in space are in the works. IF I could find a link to the people working on this I would gladly paste it, but I can't ... as of now. That is the assumption that enables all of this. Fuel Stations in Space are inevitable. IF Skylon gets operational, I am sure they will require it to return. The USAF has planes for this and may be working on it already. DO NOT take me as gainsaying you. I am pointing out your assumption is being changed. $\endgroup$ – Enigma Maitreya Apr 3 '17 at 18:25
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    $\begingroup$ @EnigmaMaitreya In space (aka vacuum) where do you get reaction mass from? You don't. You have to bring everything with you. You don't get "fuel stations", because you need to send another ship with that fuel first. Sun loses 1 billion kg/s as solar wind. At Earth orbit, it translates to 3.5 picograms per square meter. You will harvest kilogram of matter from solar wind passing through one square meter in 9 thousand years. $\endgroup$ – M i ech Apr 3 '17 at 18:41
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    $\begingroup$ @C.S.Wright Engines from what I see. SABRE engines have two modes of operation: jet (air breathing, taking oxygen from air) and rocket (closed cycle, oxygen comes from internal tanks) modes. While DC-X is supposed to have only rocket engines. Due to the way physics of reaction propulsion work, jets are much more efficient than rockets (about factor of 4), but explaining this exceeds scope of comment. Feel free to drop into factory floor chat: chat.stackexchange.com/rooms/17213/the-factory-floor $\endgroup$ – M i ech Apr 3 '17 at 21:00
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Entering and exiting the atmosphere as part of reentry has been done since the 1968 with the Russian Zond 6 lunar probe. This technique, called skip reentry, involves entering the atmosphere at a shallow angle so that the spacecraft is pushed back out of the atmosphere one or more times before reentry.

Transitioning from orbital velocities (7.79 km/s) to controlled atmospheric flight (600 m/s) burns off so much energy that you're effectively having to relaunch for each transition back to orbit. This is highly impractical.

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  • $\begingroup$ @sphennings, but could this technique, or a similar one, be used to bring a satellite or other spacecraft near the planet's surface, as opposed to simply passing through the atmosphere at an angle, which is what it sounds like you're describing? $\endgroup$ – C. S. Wright Apr 3 '17 at 17:16
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    $\begingroup$ @C.S.Wright Not if you want to enter orbit again. $\endgroup$ – sphennings Apr 3 '17 at 17:20
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I remember looking into this when I played way too much Kerbal Space Program and got sufficiently involved that I installed the fully realistic version of the game.

The accepted answer regarding aerobreaking is pretty good and covers the basics, but there's some more stuff going on that I can elaborate on and I'd like to. That answer's assertion that the technology doesn't exist yet is true, but there's also some really exciting technology on the horizon and this answer will rundown some of the methods that you'd need to do some of the things you want.

Context - What is High Altitude Flight?

Broadly, entering and leaving an atmosphere are synonymous with flying through it at any height and altitude you want. So, let's define a few terms.

The first thing is the speed of sound in air, called Mach. Usually around 330m/s but it varies with temperature and pressure. Mach 1 refers to flying at the speed of sound.

When flying at the speed of sound, the way air behaves changes and this results in the air compressing for the first time. When it compresses it heats up. Were the heat to touch the surface of a craft, it could melt the craft. Spacecraft during re-entry are specifically built (not entirely true, but close enough) NOT to fly. They don't cut through the air like a plane, they do it with a very unaerodynamic surface that creates a bow-shock that keeps the heat away from the craft. Therefore, at the moment, all re-entries don't entirely count as controlled (again, not entirely true, but good enough for now). Even the space shuttle doesn't enter like an aircraft, it enters at a 40 degree angle to the flight direction until it slows down safely enough to fly. The fastest flying plane (the SR-71 Blackbird) only got up to Mach 2 and that had to be built so that it leaked fuel on the ground to allow heat expansion caused by flying at high speed.

Orbital speed is about Mach 25ish, a long way past Mach 2. Attain that in the atmosphere and you stop flying and start lifting because you're actually orbiting. The good news from Kerbal Space Program is that, if you could fly into orbit within the atmosphere (Kerbin, the Earth-like planet in KSP only has an escape velocity of Mach 8, so this is easily doable), you can get into orbit with ridiculously low amounts of fuel. It's probably the most fuel efficient way to get there and it would probably also work on the Earth, but there are lots of problems to solve, which I'll come back to later.

First, however, I also have to talk about the atmosphere, because that's also important. For one thing, the atmosphere is thickest near the surface but the density of the atmosphere drops off exponentially the further you go away from the earth. This is both good and bad.

It's bad, because less atmosphere means less lift and less air for the engines to use. This sets a high ceiling on what's safe for aircraft to fly. The height for jet engines to keep in mind is about 26km. After that, there's not enough air to keep flying.

The good thing, however, is that there's also less air to cause drag and cause heating effects. Get high enough up into the atmosphere and you can go faster. Go faster and you can scoop up more air for use in your engines, keeping the effective density high enough to fly. We can't do this yet, but it can be done.

Because air density falls off exponentially, it's hard to say where the atmosphere finishes. The International Space Station is technically orbiting inside the Earth's atmosphere, but isn't really for most practical purposes. The number to think of for most purposes seems to be 100km.

Reframing the Problem

So, your question is nearly identical to - how to I get a plane to fly at speeds between Mach 2-25 at altitudes of 26km or above?

Well, the answer is that we can't, but we're working on it.

Jet Engines and Beyond

Jet engines work on a single principle that air speeds up as it is compressed below Mach 1 and then speeds up as it expands, leaving the jet engine at greater than Mach 1. This different behaviour below and above the Mach line is what causes the jet engine to work. Jet engines do this by sucking air in, compressing it and then heating it, spewing it out the back.

In theory, you'd think that the jet engine ceases to work functionally at speeds greater than Mach 1, but you'd be wrong. Air slows down as it enters the engine, compressing and heating itself. The effect becomes so pronounced that, were you to get up to high speeds, the turbine part of the jet engine becomes unnecessary. Air is getting sucked in and heated up anyway, you just need to add fuel and let it burn.

This type of engine is called a Ramjet and, well, we've kinda built them, because the SR-71's engines actually worked that way past a certain speed. Basically, you stick the afterburners on and the engine works, with the turbines acting as drag.

This works so well that there's a real problem. The engine overheats from the air coming in above a certain velocity and the engine explodes. This is bad. However, a British team, in trying to develop a hybrid rocket/jet engine called the SABRE have solved this and can super-cool the air and recycle the heat into the fuel, allowing jet engines to push up to a theoretical Mach 4/5. (The super-cooler exists, the engine doesn't yet, but funding has been approved, search Reaction Engines, because it's awesome.)

Above Mach 4/5, something happens to the air coming in. The air stops slowing down enough to flow below the speed of sound and instead the whole airflow is faster than the speed of sound. We go from a Ramjet to a Scramjet.

Scramjets work on the fact that the air coming in is being compressed and heating up, like in the Ramjet, so adding fuel causes it to expand more and give more thrust. It's not as efficient as a Ramjet, but good enough and is better then a rocket engine until you hit Mach 10, in theory.

Research in Scramjets is ongoing. Of the Scramjets known to exist, NASA/US Military have built one. Because of the nature of the research, it's military sensitive and therefore no one knows what happened or if it was successful. Also, the internet knows that the Chinese do not have one and did not complete tests recently (so don't ask, OK?). These seems to show speeds of Mach 6 and that the tech is possible, though why it's not being used to make cheap ICBMs is anyone's guess.

Finally, it's worth mentioning rocket engines, which carry their own reaction mass, so don't need to grab it from the atmosphere. These work (approximately) as well where-ever they are used (though the more atmosphere you have, the worse the thrust out the back is).

Flying High

So, the biggest problem with flying fast is heat and also dynamic pressure. Dynamic pressure is what the air exerts on the aircraft as it goes through it. The number to keep in your head, which is why the Space Shuttle launch system actually gets throttled back during launch, is 70,000 KPascal. More then this, you get lovely things like aerodynamical failure (aka the polite KSP term for the wings ripped off). This is bad.

You can derive that using really simple physics using a momentum transfer argument (which I invite you to either do or search for) and you'll notice it related to density, so flying fast in the upper atmosphere is not so much of a problem (though you do get heating because it's faster than the speed of sound up there).

In the lower atmosphere, it's incredibly bad and flying at close to Mach 1 close to the ground in KSP got me to 40,000kPascals near the ground (and wings ripping off, did I mention the wings ripping off?). Higher up, Mach 4/5 was not a problem.

The faster you fly, the more heat you generate and the faster you need to fly to maintain air-pressure in your engines. At the moment, heat dissipation inside engines far outstrips the ability of engines to cope with them. Since that's being solved, after that, it seems like heat to the airframe is the next problem (Mach 4-6) and both of these limit the speed at which you can go and also the height (since you can't fly fast enough to get enough air into the engines to go higher).

For this reason, the Skylon Concept, based off the Reaction Engines SABRE hybrid engine, flies up to 26km at Mach 4/5 and makes like a rocket after that.

Beyond Mach 6. I don't think anyone really knows what happens to airflow. Except NASA. They get up to those speeds on launches. But there's some odd things happening such as when supersonic air boundaries collide (this causes the rocket exhaust, which is like a jet of super-fast air, coming out behind the rocket, to widen, because it's interacting with the shock cone of air from the rocket's nose). In a feasibility study of the Skylon, the only problem NASA found with the design was that, with the engines in the middle of the craft, the rocket plumes could expand and cook the tail of the aircraft at greater then Mach 12, though a small bit of rejigging of the engine position could get the Skylon past that, but with worse control.

So, in terms of aircraft that are in the near-future pipeline, the Skylon's design is controlled flight below 26km, but at Mach 4/5, and rocketed flight beyond, which is an improvement on anything that exists. However, also the proposed SR-72 is supposed to be Scramjet driven and no one knows what it's specs will be (or whether it will be built), but if it does work and fly (remember Scramjets need a minimum of about Mach 4 to work), it will be the fastest and highest plane ever to exist.

Also worth mentioning is the Virgin Galactic plane, which uses a two stage system, with cheap, commercial flight up to a ceiling and then a rocket component from there on. Thanks to the system being two stage, the weight considerations of having two engine systems don't matter (weight considerations mean that carrying two engines is extremely uneconomical in most cases).

Re-entry

OK, this is maybe a personal opinion from playing too much KSP, but we're doing re-entry all wrong. So, I wrote that it's perfectly fine to fly up in the higher atmosphere and, well, it seems to work for me - if I have fuel.

I mentioned that all current re-entries use a bow-shock system. This causes the heat compression wave of super-high Mach speeds to stay away from touching the aircraft. This stops the aircraft from melting and, worse, exploding.

The reason this is done is that it's really, really hard to get fuel into space, so most space-craft are landing without any fuel on board. This means they're all effectively gliders.

If you have the technology for advanced spaceflight (which we'll assume for this section), you really don't want to do that. In fact, it's super-easy to make a flying transition in or even use lots of air-brakes (which again space-craft don't carry because of weight). I designed lots of space-planes in KSP that did just that and even managed to do it with a Skylon prototype in super-realism mode when it didn't quite get up to orbital speed, but close (I never did get into orbital on super-realism mode with a space-plane, I was always a Mach number or two short, make of that what you will).

I'm going to guess that the realistic way for now is purely done that way because of weight considerations and that the bow-shock method is the safest and best gliding method to use when every kilo counts (which is does with rockets). (I never could safely pull off a gliding re-entry even on the forgiving Kerbin Earth-analogue, that wasn't bow-shocked and these have to be steep to avoid bouncing off the atmosphere in the initial stages.)

If you have any thrust left on re-entry (preferably in rocket fuel, that doesn't need the atmosphere to generate thrust) and some wing-span, you can easily skip over the outer surface of the atmosphere, bleeding speed off gently until you fall into safe flight regimes for entering the lower atmosphere (I did this a lot when I missed the space center on re-entry). However, you might want to take this section with a bit more skepticism than the others.

The Shape of Things - Aircraft Design

Something that's also known, if you get into aircraft design, is that air-craft designs vary based on what speed the aircraft is designed to fly at (the flight regime).

If you see a glider, that's the optimal shape for low-speed flight. Big, wide straight wings and a body that's even vaguely aerodynamic will do.

Commercial aircraft are good designs for aircraft flying at speeds less than Mach 1 but close to it. These involve big, slightly canted and slightly swept back wings.

Super-sonic aircraft have to have very swept profiles to dissipate heating and pressure during super-sonic flight and are very sleek.

Hyper-sonic aircraft like to look like rockets, more or less, with very little in the way of wings and these so swept back as to avoid heat and pressure issues, with the body also extremely sleek and ballistic.

The problem with designing spaceplanes is that you have to design a plane that can take off and land (so flying really slowly and at low altitude), fly a super-sonic speeds and make like a rocket.

The Concorde was an example of how to fly at low and super-sonic speeds and the design was so bad at low altitude flight that, was it not for a trick involving delta wings, the thing could never have landed at a commercial airport (this accounts for its super-sized forward landing gear).

As it is, most military super-sonic jets require longer runways to take off and land on, so that the plane can get up to speed before taking off, and will use parachutes for braking.

The Skylon design, for example, is so bad at flying it needs a 3km runway and will have a water cooling system for braking if it has to abort, that's how fast it'll be going on the ground and how bad it is at flying at low speeds.

In this one way, flying into the atmosphere and flying back out is actually easier than designing aircraft for use in all the atmosphere, since you don't have to worry about pesky lift issues for landing/take-off and you can keep a profile of very small and swept back wings ideal for flight at high speeds. Or, you could use a self-lifting body, like NASA did for the Scramject test.

Conclusion

We can't do a lot of this stuff, but we're working on it. It's exciting and so check life for progress...

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    $\begingroup$ Good answer, @aphenine. I'm curious, though: would it be possible to have a spaceplane that employed both jet-propulsion and a primarily fuel-based propulsion system, and would this solve any of the issues you dealt with, such as running out of usable air (for jets) at certain heights? $\endgroup$ – C. S. Wright Apr 3 '17 at 23:29
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    $\begingroup$ Pretty good elaboration. Explains in detail why I said that what is asked for pretty much requires shedding enough velocity to count as complete re-entry. I don't imagine we will get 7.8 km/s sea level air speeds within next 200 years. One day perhaps, but not any time soon. And even when we do, I would expect such performance to come from military atmospheric craft first. $\endgroup$ – M i ech Apr 4 '17 at 0:17
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    $\begingroup$ @C.S.Wright That's the entire point of dual mode SABRE engines. They are supposed to work as air-breathing jet engines when atmosphere is thick enough, and switch to rocket mode when atmosphere runs out. Distinction in terminology is that rockets draw both fuel and oxidiser from on board tanks, while jets only use fuel, utilising atmospheric oxygen as oxidiser. Jet engines are useless in vacuum, rocket engines are inefficient in atmosphere, so if you want to have both types you lose efficiency because some engines are dead weight at any given time. SABRE is supposed to sidestep this problem. $\endgroup$ – M i ech Apr 4 '17 at 0:42
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    $\begingroup$ @C.S.Wright What M_i_ech said above. Reaction Engine's SABRE design has a rocket and jet engine mode. By combining the two together, you have an engine that is slightly less efficient at both, but saving weight. Any hybrid design that features separate engines doesn't work (and remember every kilo saved counts, so two engines are very inefficient dead space). $\endgroup$ – aphenine Apr 4 '17 at 17:45
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    $\begingroup$ Edited to add a number of improvements including mentioning rocket engines, explaining a bit more about upcoming near-future aircraft (those that are likely to see service, anyway), mentioning a problem with the Skylon design regarding shock-shock interactions and also expanding on aircraft designs for different flight regimes. $\endgroup$ – aphenine Apr 4 '17 at 18:26
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Landing on the surface of Venus would be fatal, but floating above the surface in a Zeppelin style blimp has been discussed as a means of visiting. The clouds of sulfuric acid complicate things, but on an earth-like planet, the steps would be relatively straightforward.

  1. Enter atmosphere as usual
  2. Use atmosphere to slow vehicle to appropriate flight speed - requires maneauvers
  3. Begin inflating blimp portion of spacecraft
  4. Direct spacecraft upwards into a stall as the blimp reaches full capacity

The timing would be important, as would the materials and shape of the spacecraft. The part we haven't done before - deployment and rapid inflation of a blimp - is much less complicated than building a spacecraft.

With current propulsion technology, the fuel required to get to space is heavy enough that a spacecraft must refuel every time. Additionally, the blimp will have limited means of steering, so the utility of not landing is questionable, but perhaps the floor is lava.

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    $\begingroup$ I was definitely not picturing a blimp, @user121300, but that's kind of the point of asking the question, isn't it? To hear possibilities I hadn't considered. $\endgroup$ – C. S. Wright Apr 3 '17 at 23:31
  • $\begingroup$ I was picturing a blimp :). BTW, there are various ways of refuelling in the atmosphere. For example, there are planes that are designed to fuel up other planes. On a primitive but earth-like planet, you could still refill your liquid hydrogen tanks with a solar cell, a dehumidifier and a pair of electrodes (given enough time). $\endgroup$ – gmatht Apr 5 '17 at 6:25
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If you have energy to spare, sure.

If the vehicle can support itself against gravity on thrust alone for extended periods of time, it can do this with no fancy maneuvers. That just takes lots of continuous thrust. I wouldn't try it with a reaction drive though since that sort of maneuver will get expensive. It would be easier if you have a reactionless drive like: impulse drive (Star Trek), inertialess (Lensman), magnetic repulsion (lots of '50s aliens), or some other science fiction drive. Otherwise, you are limited by the amount of reaction mass you can carry.

Another thing that would help would be a way of minimizing G forces inside the ship. That makes speed changes more comfortable/survivable.

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    $\begingroup$ Expensive might be the biggest understatement I've ever seen on this site. It's totally impossible with any rocket we know how to make. With chemical rockets, you're looking at 500 metric tons of fuel left at the point you leave hover. $\endgroup$ – Leliel Apr 4 '17 at 1:27
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    $\begingroup$ So, @Leliel? The OP specifically asks whether this is possible with "a spaceship of some sort", then goes on to state that it's impossible for us today, but whether it is theoretically possible in any way, form or fashion at all. While all other answers are really fascinating, this one here is correct. If you bring the energy (in any way a future spaceship may have at its disposal), then you can surely do it. I am pretty sure nobody will suggest that what we have as drives/fuel today is the ultimate pinnacle that can never, theoretically, be surpassed (how about fusion etc.). $\endgroup$ – AnoE Apr 4 '17 at 15:05
  • $\begingroup$ @Leliel - It's a pretty boring question if it can only be answered in the context of "rockets we know how to make". This is world-building after all, and no 'science-based' tag is present. That means hypothetical (or even implausibly hypothetical or just plain magical) solutions are entirely in bounds. And that the answer is basically "yes, if you have a sufficient energy source (whether fission, fusion, antimatter, unobtainium, or whatever) and sufficiently powerful thrusters (whether traditional, ion, antigrav, etc.), you can do this". $\endgroup$ – aroth Apr 5 '17 at 3:31
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In very simple terms, it's much easier to exit the atmosphere if you don't land.

In order to leave a planet's gravity you need speed - if you enter the atmosphere from orbit then of course you will slow down from drag, but may well still retain a lot of velocity, making it easier to accelerate up to exit velocity. If you land, then you'll have to start again from scratch (although of course once you're on the ground, then refuelling might be a possibility).

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    $\begingroup$ It's a good point, @Matt Bowyer, but it only applies if you're using the initial velocity of atmospheric entry to subsequently exit said atmosphere. In other words, there'd be no slowing down or performing various functions just above the planet's surface, which is what I have in mind. $\endgroup$ – C. S. Wright Apr 3 '17 at 20:41
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    $\begingroup$ Sort of - if you slow down then my point is still valid (it requires less energy to accelerate from 1,000m/s to 10,000m/s than it does from 0m/s to 10,000m/s) - obviously if you want to slow right down or stop at low-level then essentially you're in much the same situation as if you'd landed. If you want to slow right down in the upper atmosphere then you're still at an advantage - as there is much less air resistance to impede your acceleration. $\endgroup$ – Matt Bowyer Apr 3 '17 at 21:45
  • $\begingroup$ Yeah, good point. Either way, am I correct in assuming that being in orbit before entering the atmosphere makes it easier to pull this off? $\endgroup$ – C. S. Wright Apr 3 '17 at 23:03
  • $\begingroup$ @MattBowyer while technically true that it requires less energy to speed up again from 1000m/s than 0, you're not going to take advantage of that with any hard science-based drive, you're firmly in the realm of semi-magical to get the power level and deltav required. For anything buildable on earth without unknown physics, it's easier to land, so that you can refuel. $\endgroup$ – Leliel Apr 4 '17 at 1:22
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Going strictly off of your original question without knowledge of your comments specify more, then yes it's possible, and yes we probably do have the technology right now to do it.

If you look at Blue Origin's New Shepherd rocket, it's designed to burn straight up until it's apogee is above the limit of space, release the crew capsule, and then coast until it starts to fall back to earth, and then do a landing burn before touching the ground.

If they were to modify the rocket a bit, add more thrust to the engines, and a LOT more fuel, they could fly the entire rocket up until it makes it into space, fall back down, and instead of landing, just keep burning and head back up and do it again, and potentially come back and land.

Doing this however would be the equivalent of a billionaire taking out all his money in cash, and deciding instead of doing anything useful with the money, just light a match and watch it burn away.

The only reason for Jeff Bezos to do a thing like this would be to break the record for most expensive "Fuck you Musk, we did it first because we can!" in the world.

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One thing I haven't seen mentioned here is an inflatable heat shield.

You don't say much about what you're trying to do with your non-landing spacecraft, but an inflatable (or just a straight-up detachable) heat shield could be used to bring a fully-fueled rocket/spaceplane into the atmosphere, aerobrake it to some kind of manageable atmospheric speed, detach the dead, useless mass of the heat shield, then allow it to accelerate out of the atmosphere again.

This is strictly a single-shot solution, but it could conceivably, for example, be used to drop a rescue craft into an atmosphere, pick up a stranded operative using a Fulton recovery device then quickly winch the operative aboard and get back into space without needing a launchpad.

It's not a ride I'd like to take, it's not reusable and it ain't gonna come cheap, but it's something almost workable...

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    $\begingroup$ This would allow it to withstand more heat from reentry. Slowing down enough to pick a human (55m/s) is going to require a lot of energy to accelerate back to orbital velocity (7.79 km/s). $\endgroup$ – sphennings Apr 4 '17 at 16:19
  • $\begingroup$ I've seen inflatable heat shield-type technology used in sci-fi before, but I didn't know they were actually feasable. $\endgroup$ – C. S. Wright Apr 4 '17 at 20:16
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    $\begingroup$ @C.S.Wright I suspect that a massive, detachable heat shield is going to be the only way to do this. It's been touched on in other answers, but all of our survivable deorbiting tech is designed to return on empty or near-empty tanks. Your scenario requires the de-re-orbit craft to be carrying enough reaction mass to lift something back to orbit. So you don't just need to slow down a rocket, you need to slow down a fueled rocket. Take a Falcon 9 stack, lay it on its side, encase all that in a gigantic heat/deceleration shield and all that might get a small, manned pod back into orbit... $\endgroup$ – Frosty840 Apr 5 '17 at 9:52
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Yes it can by building a 4 edge or 2 edge triggering system to maintain the atmospheric pressure along the spaceship. Then it can act as a shuttle by providing enough pressure inside the bridge, allowing it to act as a both outbound and inbound spaceship

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    $\begingroup$ I'm confused by what you mean by a triggering system. Could you elaborate on that? $\endgroup$ – sphennings Apr 5 '17 at 14:56
  • $\begingroup$ Yes, @user35584, this seems like a good answer, but I'm not sure what you're saying. Please clarify what a triggering system is. $\endgroup$ – C. S. Wright Apr 5 '17 at 18:05

protected by James Sep 11 '17 at 15:41

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