Parachuting Astronauts to the Surface of Other Planets/Moons- A Little Idea That I Just Had

[Thomas988]

As a little forenote, I just want you guys to understand that this isn't idea I haven't put much serious thought into, mainly because I don't know that much about physics and whatnot. Really, what I'm trying to say that don't expect this to be the most sophisticated idea you all will ever read.

So, after a moment of randomly thinking about hum spaceflight, I realized something that could make landing on other celestial bodies with atmospheres conceivably cheaper and perhaps more feasible: why not parachute astronauts down to the surface and have them rendezvous with a pre-landed spacecraft that could bring them back into orbit? The only problem I can see at the moment is the large probability that our astronaut(s) would land too far away from the landed spacecraft, but, given that this wouldn't happen, what else could go wrong?

Let's discuss!

[Alshain]

Why is parachuting to the surface more ideal than simply riding in the pre-landed space craft?

[Sampa]

True, it would be cheaper. However, we'd also need to consider a disposable heat shield that would more than likely crash to the surface after the said astronaut was done using it. Also, the shear forces an astronaut would experience during such a ballistic entry backed by what would probably be an extremely stiff space suit...he would most likely be unable to even deploy his parachute. Next, some planets, such as Venus, though it does have an atmosphere, the pressure would be too great for an astronaut to survive long enough to even make it to the surface, let alone to a spacecraft.

[Thomas988]

Why is parachuting to the surface more ideal than simply riding in the pre-landed space craft?

The point I am trying to make here is that instead of taking a large, complicated spacecraft onto the surface and coming back, astronauts could ride a small spacecraft to deorbit, then from there just use gravity bring them down and a parachute to slow down. Surely a spacecraft capable of deorbiting, landing, and returning to orbit would require more fuel than a spacecraft that would only have to carry humans into orbit. And that's excluding all the mechanical/technical problem that could occur onboard.

But, like I said in the OP, I'm no expert on this stuff, so if I'm rambling nonsense just kindly let me know.

- - - Updated - - -

True, it would be cheaper. However, we'd also need to consider a disposable heat shield that would more than likely crash to the surface after the said astronaut was done using it. Also, the shear forces an astronaut would experience during such a ballistic entry backed by what would probably be an extremely stiff space suit...he would most likely be unable to even deploy his parachute. Next, some planets, such as Venus, though it does have an atmosphere, the pressure would be too great for an astronaut to survive long enough to even make it to the surface, let alone to a spacecraft.

True, true.

[Bill Phil]

It just seems like a waste of resources at best unless there was no return plan. You need another system, capable of keeping an astronaut alive through reentry and until he/she gets to the ship. Would it kill you to just land a base with the astronauts and a separate lander? And if you already have a lander, why not use it?

[meve12]

Remember that you have to bring the return stage down anyway, which is also going to require a heat-shield, aeroshell and some sort of braking device.

SO you might as well use it for the leg down.

[Greenfire32]

The biggest hurdle is re-entry effects. Do you know how hot it gets when a spacecraft slams into the atmosphere at stupid-fast speeds?

People would fair much worse.

And then there's the shear force of "wind" you'd experience. Ever stick your hand out the window while driving down the highway? Imagine that. But your whole body. And going miles per second instead of miles per hour. And don't forget you're basically on fire the whole time too.

[BagelRabbit]

As a little forenote, I just want you guys to understand that this isn't idea I haven't put much serious thought into, mainly because I don't know that much about physics and whatnot. Really, what I'm trying to say that don't expect this to be the most sophisticated idea you all will ever read.

So, after a moment of randomly thinking about hum spaceflight, I realized something that could make landing on other celestial bodies with atmospheres conceivably cheaper and perhaps more feasible: why not parachute astronauts down to the surface and have them rendezvous with a pre-landed spacecraft that could bring them back into orbit? The only problem I can see at the moment is the large probability that our astronaut(s) would land too far away from the landed spacecraft, but, given that this wouldn't happen, what else could go wrong?

Let's discuss!

If you're talking about having the return vehicle already landed when the astronauts arrive: yes, this is a feasible thought that has seriously been considered by NASA for their Mars program.

If you're talking about having astronauts "parachute" down to the lander in their space-suits:

There are only really three places in the solar system besides Earth that have an atmosphere with a solid and explorable surface below: Venus, Mars, and Saturn's moon Titan.

On Venus, there are a number of very good reasons why not to go there. To briefly recap: It's really hot, it's got an absurdly thick atmosphere, it rains sulfuric acid in the upper atmosphere and "snows" metal on the surface, etc., etc., etc. In addition, the atmosphere would quickly thicken, subjecting any paratrooper to enormous G-loads and temperatures of thousands of degrees. You would probably die long before you reached the ground.

On Mars, the atmosphere is far too thin to rely solely on parachutes to reach the surface. If you were to pull a conventional human-rated Earth parachute in the lower layers of the atmosphere, you would hit the ground at over two hundred miles per hour. If you had some sort of retro-rocket belt, then the scheme could work... although with all of the variables involved in landing on a planet, it likely wouldn't. A human can only carry so much fuel and guidance sensors around his or her waist.

On Titan, the atmosphere would be rather thick, enough to allow a parachute. However, entering the atmosphere would provide massive G-loads and high temperatures, both of which would make it quite difficult to survive.

Keep in mind, the fastest that any human being has ever been while travelling in free-fall is a "paltry" 800-ish miles per hour. The slowest possible entry speed from orbit would be almost ten times that fast.

In other words: it's possible, but highly unsafe and highly unlikely.

[EDIT: Ninja'd and Ninja'd and Ninja'd. I need to learn to type faster.]

[Fingal]

Jeb says he's up for it.

[Thomas988]

It just seems like a waste of resources at best unless there was no return plan. You need another system, capable of keeping an astronaut alive through reentry and until he/she gets to the ship. Would it kill you to just land a base with the astronauts and a separate lander? And if you already have a lander, why not use it?

Thanks for the info, guys. Primarily I made this thread so I so some much more intelligent people could look this over and let me know if this is feasible or not. The verdict is: not really, and not that cost-effective.

I'm going to call this discussion over.

EDIT: And just so make myself not look like an idiot, I did realize the re-entry problem a millisecond after I published the thread. I play KSP, dangit, why aren't I remembering these things?!

Edited January 12, 2015 by Thomas988

[PlonioFludrasco]

Forgot about re-entry heat?

Seriously, that astronaut must be equipped with an heat-shielded EVA suit, if you want him to reach the surface. Also, the human body is far from having a good shape for the task. You can think about a suit that overcome that problem by having a very different shape than the astronaut inside, but what you have now is more a one-seat capsule, maybe an inflatable one that doesn't need much space to be stored. Even if it's not properly a suit, it's not a bad idea.

Once subsonic, the astronaut can leave the capsule and landing on it's own, if the pod has not it's own chute.

[Bill Phil]

Maybe for an ISS escape pod or something like that.

[PakledHostage]

EDIT: And just so make myself not look like an idiot, I did realize the re-entry problem a millisecond after I published the thread. I play KSP, dangit, why aren't I remembering these things?!

Maybe BECAUSE you play KSP with its conspicuous lack of re-entry heat?

[Louella]

what about Zorbing ?

wasn't there one of the Mars rover missions that was intended to land, or did land, by being inside a giant balloon/airbag that deflates on impact ?

I can see a possible advantage to having an ascension craft land by airbag/balloon/zorb, and the astronauts descend seperately, then assemble it properly for takeoff, but again, it does seem a bit out there to parachute from orbit.

Could see zorbing as being a thing for landing large numbers of equipment canisters, or other unmanned stuff, if there's a limitation on being able to control stuff from Mission Control in orbit/on Earth, because of time delay/bandwidth/power issues.

[Armchair Rocket Scientist]

what about Zorbing ?

wasn't there one of the Mars rover missions that was intended to land, or did land, by being inside a giant balloon/airbag that deflates on impact ?

I can see a possible advantage to having an ascension craft land by airbag/balloon/zorb, and the astronauts descend seperately, then assemble it properly for takeoff, but again, it does seem a bit out there to parachute from orbit.

Could see zorbing as being a thing for landing large numbers of equipment canisters, or other unmanned stuff, if there's a limitation on being able to control stuff from Mission Control in orbit/on Earth, because of time delay/bandwidth/power issues.

Airbags can and have been used on manned spacecraft landing on Earth, with descent velocities of a few feet per second, but for a Mars landing you're going much faster, and when you bounce you may land in a bad orientation. The human body tolerates high accelerations best "back-to-front," followed by "feet-to-head." Our G-tolerance is much lower if we land upside-down or sideways.

The type of lithobraking Spirit and Opportunity did is equivalent to subjecting astronauts to a rollover car crash at highway speeds.

However, airbags would be an excellent landing method for bulk cargo such as food or water, provided you had a way of retrieving it since it will probably bounce several hundred meters in a random direction from where it lands.

[Impaler]

Starship Troopers by Heinlein has something like this, they use a ablative heat-shield-shell and some kind of jet-pack for touch-down.

[Scotius]

Parachuting isn't 100% safe even on Earth. No space agency will pour hundreds of millions of dollars into sending their highly trained, indispensable astronaut to another planet and have him parachute to the surface, where he\she can break a leg (or neck) immediately on touch-down.

[Nibb31]

Surely a spacecraft capable of deorbiting, landing, and returning to orbit would require more fuel than a spacecraft that would only have to carry humans into orbit.

And how do you get that spacecraft onto the surface of the planet without deorbiting and landing it first?

[KerikBalm]

Surely a spacecraft capable of deorbiting, landing, and returning to orbit would require more fuel than a spacecraft that would only have to carry humans into orbit. And that's excluding all the mechanical/technical problem that could occur onboard.

There's a massive problem here... unless you have offworld manufacturing... you have no way of getting your spacecraft that would "only have to carry humans into orbit" - to the surface in the first place, you need to deorbit and land it there. Thus, in both cases, you need to deorbit and land a spacecraft, and then have it ascend again.

Obviously, you could stage it, like Apollo did, so that the ascent stage is lighter, and a fully fuelled ascent stage is not capable of de-orbit+ land+ ascent again.

The propsals to pre-land spacecraft on mars are tied with ISRU, where the craft lands, and then begins producing rocket fuel from the atmosphere + stored hydrogen + power from a nuclear reactor. Also in these cases, you not only need to land a return vehicle, but rovers, habs, etc - and the astronauts can come down with one of those.

No space agency will pour hundreds of millions of dollars into sending their highly trained, indispensable astronaut

Lets cut down on the hero worship... astronauts are not indispensable, and the required training is miniscule compared to the cost of the rocket, when you consider much of it would be handled by a computer.

Edited January 13, 2015 by KerikBalm

[Meithan]

Starship Troopers by Heinlein has something like this, they use a ablative heat-shield-shell and some kind of jet-pack for touch-down.

Something like the MOOSE system, perhaps?

[Sampa]

Parachuting isn't 100% safe even on Earth. No space agency will pour hundreds of millions of dollars into sending their highly trained, indispensable astronaut to another planet and have him parachute to the surface, where he\she can break a leg (or neck) immediately on touch-down.

Actually, you are not entirely correct...

The early Soviet Vostok missions actually intended for Cosmonauts to parachute to the ground OUTSIDE their capsules (which ended up crashing into the ground below). Yuri Gagarin was one of those few.

[GreeningGalaxy]

Having a pre-landed return vehicle on the surface before you descend makes all kinds of logistic sense - once the lander descends intact, it's there, and it then doesn't matter how well you land the descent vehicle as long as you don't kill yourself in the process. With single-lander missions, you have to be careful not to damage the engine on landing or you might never be able to go home, but with separate vehicles, you'll know before you even launch the humans whether or not the uncrewed ascent vehicle landed safely. If it made it, you're good to go; if it didn't, nobody was relying on it to get home because they haven't even left Earth yet. That also opens up some nice ISRU possibilities - the lander could make methane/LOX fuel from stored hydrogen (or found water ice) and CO2 from Mars's atmosphere while it waits, for instance.

As for parachuting to the ground, it's technically possible (albeit very kerbal), but for reasons of safety and also being able to carry a lot of scientific equipment down too, it's probably better to land a full habitat with just enough fuel for touchdown. Such a thing wouldn't weigh very much, and you could use it as a base of operations prior to leaving on the ascent vehicle.

Interesting idea, but I think the MOOSE system and its kin are not really the kind of thing you want to be using regularly.

[Tech Support]

This reminds me of the drop pods used by the ODST Hell Jumpers in Halo, then again, that is pure fantasy and with a different purpose ( Rapidly inserting soldiers into combat zones ).