back to article Space dogs and Dragons: A brief history of reentry tech

In August 1960, Soviet dogs Belka and Strelka1 - accompanied by several mice - became the first animals to travel into space and return alive. Belka and Strelka seen inside the Vostok capsule Belka and Strelka seen inside the Vostok capsule Packed into their Vostok spacecraft, the space canines relied on some venerable …

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Capsule parachutes

As I recall, one chute failed to deploy on Apollo 15 resulting in a bumpier splashdown.

Also, Mercury had an additional egress point in which the astronaut had to climb-out the top of the capsule.

http://spacemedicineassociation.org/timeline/1960/1960%20Jan-June/Glenn%20Langley%20Egress%20Training%201960.jpg

I strongly recommend watching the Discovery channel documentaries MoonMachines and especially the ones about the Apollo capsule parachutes. According to the guy who designed the parachutes, they were so tightly packed that they had the density of maple wood! Another section that I really liked was about the Launch Escape System (LES) which is designed to pull the capsule in case the Saturn rocket goes kaput. This actually failed during testing (the rocket came apart) and caused LES to fire which was a verification of an actual failure.

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Paraglider and helicopters

At one point the Gemini capsule was going to return to Earth under a paraglider:

http://www.youtube.com/watch?v=jub8y6WSI8M

and very early on, Apollo looked at using rotor blades to perform a landing rather than a splashdown.

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Re: Paraglider and helicopters @<ike Richards

Rotary Rocket used a helicopter approach, and Armadillo Aerospace are using paragliders to return the STIG to the launch site.

What goes around comes around.

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Re: Paraglider and helicopters @<ike Richards

Rotary Rocket's Roton ruled! Here's the YouTube: http://www.youtube.com/watch?v=X--EDUqP9wI

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Black Helicopters

Re: Paraglider and helicopters

Korolev (the daddy of the USSR space program) also fancied the idea of a rotor based landing system for Vostok. Despite being in charge, he was over-ruled and they ended up with the relatively well tested parachute and rocket system.

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Alien

splashdown at 35km/h...

Ouch.

My *reserve* chute drops me at 4.5m/s (16kph) and with that I want a rolling fall in the approved manner; my paraglider drops me at around a meter a second and even then you can get bruised if you don't do it properly - say, trip on landing.

35kph is slowish car crash without benefit of crumple zones...

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Pint

Wow

This makes my distressing return home using Greater Anglia a positively fluffy kitten.

<----A beer for the brave Men and Women that do this

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"Rocket science"

A strange mix of extraordinarily advanced things (e.g. MSL/curiosity), implemented on much less advanced hardware (for reliability/radiation resiliance/etc.) and carried aloft (or returned to the ground) by some very primitive techniques indeed (set fire to this bit, add more heat shield to this bit).

Reminds me of a description in a very early non-discworld Terry Pratchett book where there is a description of what a valve would look like if technology had advanced but the transistor had never been developed. Bit like modern cars too - still basically propelled by burning dinosaur and rolling along on rubber sausages ...

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First Fatality

Wouldn't the alleged lost cosmonauts be the first fatalities, pre-Gagarin http://en.wikipedia.org/wiki/Lost_Cosmonauts

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>It wasn't until 1783 that Frenchman Louis-Sébastien Lenormand jumped from the tower of Montpellier observatory and lived both to tell the tale and invent the word "parachute".

Fair dooes! Personally, I would have placed my body-weight in courgettes in a bag, and tied the bag to my new parachute invention - before dropping that off the roof. Still, you can't knock showmanship!

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FAIL

"hammered the thing in with wooden mallets"

Good, that'll stay put...

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Downside of retro-rockets

Just an observation: It seems so obvious to use rockets here that one might wonder why they aren't used more extensively.

Well, besides additional complexity and risk (over-and-above the already complex and risky 'chutes) is weight: Using parachutes gives you a "free" slow-down by using the atmosphere, whereas the additional rocket-fuel is extra weight you have to take up with you in the first place, and thus reducing your useful payload.

Of course, on the Moon you have no significant atmosphere, but the reduced gravity-well allows you to use smaller retro-rockets. Mars is a problem: There's a bit of atmosphere, but much less than Earth's, but a much higher gravity than the Moon.

Which just makes the whole NUCLEAR-POWERED, LASER-ARMED TANK ON MARS project so much more awesome. That landing system used a complex arrangement of both rockets and parachutes, and it worked flawlessly.

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Go

Re: Downside of retro-rockets

Yup. Of course, there's another side to it as well: one reason why SpaceX are so keen on landing the Dragon and the first stage on rockets, is that they're *already* carrying engines and tankage. Adding the extra capacity to land on those same rockets adds very little extra mass and improves flexibility no end --- and at the same time allows them to omit the bulky and unreliable parachute system.

Incidentally, I'd strongly recommend anyone with a passing interest in this sort of thing to go get the Kerbal Space Program demo and actually try it. Their physics engine is pretty crude but a good enough approximation to the real thing to give you a feel for how rockets really work. It's surprising quite how little fuel you need to land, for example. Even without a parachute you get a huge amount of free braking from the atmosphere.

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Mushroom

Re: Downside of retro-rockets

I'll second that..... you also do a fair re-creation of the heady days of early rocket attempts by building something that barely flies , then explodes.

But when you finally achieve your first orbit, after all the crashes and failures, you sit back and bask in the glory of a job well done........ until you notice the moon.... and all the other worlds to visit/explore/crash into

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Re: Downside of retro-rockets

The problem is that you need much more powerful engines and much more fuel for a powered landing (compared to engines you only need for orbital maneuvering and reentry). You'll also have to brake speed within seconds (since doing it more slowly would need even more fuel) before hitting the ground. And you need to do all this while having a ton or so of highly explosive and highly toxic hypergolic fuels (which need no ignition but will happily jump into fiery action as soon as they see each other) on board right beneath your seats, along with all the plumbing and valves and tanks and whatnot.

What SpaceX is trying to do here is really ambitious. Their powered landing scheme is very much a planned spectacular suicide that goes very subtly wrong if everything works right. Love it!

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Re: Kerbal Space program

Oh my yes. I already have a crew of three stranded on Laythe without QUITE enough delta vee to get back into orbit to meet their ride home. I am designing a rescue mission with a much beefier lander to go get them.

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Flame

Re: Downside of retro-rockets

As far as I know, the retro rockets on Dragon are also used as an emergency abort system if there's a problem during lift-off.

Assuming there's no problem, then you might as well use them on landing right?

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Anonymous Coward

Didnt they already land vertically ?

Yes, Im sure I saw something come down and land vertically, just like you say will be possible in the future.....but that was in the 60s and on the moon, or maybe wasnt......

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Missing

Shame the VentureStar SSTO project has been forgotten in the lineup of "things tried"

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FAIL

Re: Missing

Things tried? V* didn't even get a finished vehicle. They used the tank problems as an excuse to cancel it.

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Re: Missing

Ironically the stubborn engineers successfully solved (and even tested) the tank problems right while the funding was cut and the thing was being cancelled.

X33/Venture Star was a really ambitious project but it could have worked out. And a fully reusable Single Stage to Orbit craft is nothing to sneer at.

By the way, you need an empty/fueled mass ratio of about 1:10 to make this work (meaning that at launch 90% of the mass is fuel). SpaceX's Falcon 9 first stage has a mass ratio of 1:30, it could propel itself and quite a bit of payload into orbit all by itself (but of course adding a second stage gives you much more payload for not much money).

This is not the last word on SSTO.

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Pint

Thumbs up for accurate reporting

I have to send a virtual beer to Lester, since it's well done and balls-on accurate. I can't even nitpick it. That's really rare for anything space-related.

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(Written by Reg staff) Silver badge

Re: Thumbs up for accurate reporting

Thanks - I accept your kind offer of a pint. We do try and check stuff, then check it again. And if an error does slip through the net, you lot let us know quickly enough ;-)

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Headmaster

Re: Thumbs up for accurate reporting

Apart from the little bit of futurology on one of the photo captions:

"... Chris Hadfield (R) squeeze into a Russian Soyuz-TMA capsule shortly before their return to Earth in May 2103"

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(Written by Reg staff) Silver badge

Re: Re: Thumbs up for accurate reporting

Indeed. Next week, I'll be bringing you the winning Euromillions lottery numbers for the next five years.

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Boffin

A note on rockets and parachutes.

Soyuz is split into 3 segments and the landing compartment is the smallest. The Russians worked out you could optimize the weight of the whole system by basically dedicating a small part of it for this one function. Minimal volume -> minimal surface area to protect with (heavy) ablative and you can afford some retro rockets (triggered by a gamma ray altimeter).*

The US decided to go with a mult-function capsule with a proportionately bigger (much bigger) heat shield.

*A design which GE had proposed to NASA in one of the first govt/industry conferences on what would be Apollo. Before NASA announced that as the design had to fit the Saturn 1 they had essentially already decided what the design was and GE (and the other 22 companies who turned up) might as well not have bothered. GE was the #1 designer of re-entry vehicles on the planet at that time (they did the designs for ICBM's and knew a lot about real world re-entry heating.

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Re: A note on rockets and parachutes.

"GE was the #1 designer of re-entry vehicles on the planet at that time (they did the designs for ICBM's and knew a lot about real world re-entry heating."

Just that ICBMs have totally different requirements than landing capsules, they hit the ground (well, ignition height) with still several km/s, something you don't want to have with something that you actually want to recover.

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Oak

I'm sure I read that one of the Chinese capsules had a heat-shield made of oak. Maybe that was just Yankee devil propaganda.

I don't know why an oak heat-shield should be funny. If it's a suitable material it makes sense to use it. But I can't get rid of the image of astronauts re-entering the atmosphere on a dining table.

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Re: Oak

Oak or cork seems to work fine for that, it's not much different from epoxy ablative heat-shields at all. Quality control is hard though. But there are much better materials available now.

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What keeps the parachutes apart?

Title says it all? When you have more than one parachute, what force separates them? They are all tethered close together on the capsule. Why doesn't aerodynamic drag make them move together until they form a single, segmented, hemisphere? I could see how this could work if the parachutes or their vents were asymmetric, but then they'd need divergent tethers to stop them rotating.

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Go

It comes down to which way you want to do things...

With parachutes, you slow down, land and then stop (quickly).

With rockets (can't wait for Dragon Mk II), you slow down, stop and then land. Much less bumpy.

One system is somewhat simple - It REALLY needs to be properly set up though. Pay those parachute packers a fortune, guys!

The other is somewhat complicated but that's the way things'll go in the future. A modern sedan car is fiendishly complicated compared to a Ford Model T but as long as the technology is reliable (enough), I'll take the modern car any day...

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Re: It comes down to which way you want to do things...

"A modern sedan car is fiendishly complicated compared to a Ford Model T but as long as the technology is reliable (enough), I'll take the modern car any day..."

That's fine if you're commuting in the city, or country driving in English farmland, because you can just call the RAA or AA or whoever handles emergency vehicle callouts in your country.

However, I live in Australia, where distances between major cities run into four digits. And those four-digit distances encompass some of the nastiest areas on the planet - searing temperatures, baking sun, no shelter, no water (or in flood season far too much of it), poisonous beasties, and so on.

In such circumstances I'd personally prefer the Model T (or simple equivalent) because if it breaks down you can get it going again - at least to the next town - with the elastic from your undies and a bit of fencing wire. As opposed to your you-beaut modern sedan, which will simply sit there and refuse to go the moment its computer gets upset about a scratched EFI cowling or something, and which will require some hideously expensive and needlessly complicated part imported from the other side of the planet to fix. Which in this country makes that sedan a potential deathtrap on wheels.

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Re: It comes down to which way you want to do things...

Well for things like the Australian outback, I'd say that Steven Roper is right, but we are, I thought, discussing ways of getting down to the ground from orbit (or at least down from a very high place).

To apply the situation though, I'd still favour rockets (complex) over parachutes (simple) because each capsule is checked prior (and once reusability comes into play, afterwards) to each use by a specialist team. Think of that complex sedan getting a full checkup at a maker-approved service facility prior to (and again, once reusability comes into play, afterwards) each outing.

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Coat

What about Mjolnir armour?

I saw a war documentary once where a guy jumped out of a space ship in orbit and landed on earth with no ill effects!

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