How did people know how to build the first space ship?



How did the early designers of spacecrafts have any idea what space was actually like?

How was a vessel ever constructed that actually flew through Earth's atmosphere without burning up, and then was able to travel around once it reached space without just freezing up?

How did they ever speculate no gravity and train astronauts according?


Posted 2017-08-09T18:33:47.233

Reputation: 395

3People knew what was in "space" from observations from weather balloons. Also the first satellites didn't have do anything except broadcast a radio signal. – None – 2017-08-09T18:46:45.753

42The answer is: science. Science as a process of discovery, experimentation, and most importantly, progressively building on what you know to learn something you don't. "What to expect in space" comes from the accumulation of a lot of knowledge, experimentation and discovery stretching back to the ancient Greeks progressing through Kepler and Newton (among many others), the development of aviation and rocketry, all revealing new information about what's up there or confirming theories. Insight may be gained from studying the history of science.Anthony X 2017-08-10T00:24:18.137

8Thousands of experiments spanning the course of centuries and millions of trial and error...dalearn 2017-08-10T01:01:22.583

5Quite a few of the early rockets did blow up, often quite spectacularly. For knowing about space, Newton's Laws of motion & gravity tell us about orbits and zero-g. while we know it must be a (near) vacuum because otherwise the moon's orbit would decay because of air friction.jamesqf 2017-08-10T04:43:29.890

2@jamesqf But the blow-ups were either engine failure or deliberate scuttling when guidance systems went wrong. Nothing to do with gravity, atmosphere, or space aliens :-)Carl Witthoft 2017-08-10T13:30:46.797

3Could you apply this question to any new invention or experiment? The first aeroplane, the first SCUBA, the first nuclear bomb etc..Steve Smith 2017-08-10T15:27:15.900

@Carl Witthof: Gravity wasn't a problem. Apollo I was lost due in part to atmosphere problems. And we haven't run into aliens yet :-)jamesqf 2017-08-10T17:48:34.680

Because Aliens. It's the only way, right?Ellesedil 2017-08-11T06:34:47.260

Btw, there's no freezing up in space. It's possible to boil to death tough. vacuum is an insulator (there's literally nothing in a vacuum that could transfer heat), so any energy you produce in your spaceship stays there and accumulates. Pretty much all you have for cooling is black body radiation and the ability to jettison anything that's hot.Peter 2017-08-11T08:49:30.920

2Obviously they used Kerbal Space Program ;)DeepSpace 2017-08-12T11:19:12.013

@A.C.A.C. Actually, Sputnik 1 had temperature and pressure sensors. The data was encoded into the radio beeps. And electron density of the upper atmosphere was deciphered by analyzing the radio signals. In fact, the Soviets originally intended to launch "Object D", which was a much more complex sputnik with many more sensors and even a magnetic tape recorder. Delays with Object D caused the authorities to switch to the simpler Object PS, which became Sputnik 1. Object D finally launched as Sputnik 3, tho the tape recorder failed soon.DrZ214 2017-08-12T21:15:14.610

1How did people know how to build the first computer, the first audio-tape recorder, the first television, the first pencil, the first wallet, the first glass of orange juice, the first magnet?immibis 2017-08-12T23:46:36.847

Trial and error, and the demise of many, many small animals.Strawberry 2017-08-14T11:45:53.707



This is a very broad question, but I'll take a stab at it.

It was understood that gravity pulled the Earth into a spherical shape, with dense solids and liquids below less-dense gases, and it was expected as early as the 17th century that the atmosphere would get steadily thinner with increasing altitude, giving way to vacuum. These expectations were confirmed with e.g. balloon observations as @ACAC notes.

Vacuum chambers on the ground were straightforward to make, so predictions about heating and cooling of a vehicle in the vacuum of space could be confirmed.

Heating due to high speeds in air was also understood from the 1920s, and the extremely high temperatures encountered during reentry into the atmosphere from near-orbital speeds were studied with ballistic missiles through the 1950s.

Flying ballistic trajectories in aircraft simulated weightlessness for short periods, allowing astronauts to prepare somewhat for the experience.

Russell Borogove

Posted 2017-08-09T18:33:47.233

Reputation: 57 784

4Thank you so much! I really appreciate you taking the time to answer and help clear some of this up!korrinab 2017-08-09T19:51:48.023

2...and effects of prolonged exposure to microgravity were entirely unknown, so all early cosmonauts were equipped with cyanide capsules...SF. 2017-08-10T11:56:38.637

7@SF Citation needed. If microgravity makes you long for death, you re-enter early. If you need to kill yourself in a spacecraft, you depressurize the cabin.Russell Borogove 2017-08-10T12:10:27.170

@RussellBorogove: Here's one for Voskhod 2, in case Leonov was unable to reenter the craft (and depressurizing a space suit is way easier than depressurizing a spacecraft). I'd have to hunt down the rest.

SF. 2017-08-10T12:17:13.860

2@SF I'm contesting your suggestion that there was a connection between the unknown effects of exposure to microgravity and cyanide capsules. Voskhod 1 had already flown a day-long mission at that point. (The cyanide pill story is dubious to begin with -- see Mary Roach in "Packing For Mars" -- but that's not what I'm arguing right here.)Russell Borogove 2017-08-10T13:01:10.633

@RussellBorogove: I'm quite sure the primary reason for the pill was that in case the craft was unable to deorbit before it ran out of life support supplies, but at least in case of first Vostoks the effects of prolonged microgravity exposure were one of most important scientific goals, a major unknown. The cosmonauts were to use the pills if they were unable to return to Earth for whatever reason; if automatic reentry sequence failed and the astronaut was incapable of performing manual sequence e.g. due to being incapacitated through microgravity, that would be one possible scenario.SF. 2017-08-10T18:12:57.217

(so my suggestion is a stretch, but not a fabrication. Kinda like I'd say they had a gun on board to defend from wolves; the gun was widely multi-purpose, and with general "survival" focus, but wolves were among specific concerns why it was there.)SF. 2017-08-10T18:18:12.917

More like saying there was a gun on board to deal with angry carp, but okay.Russell Borogove 2017-08-10T22:00:09.593

3@SF: gun to defend from wolves - yes. Not in orbit, but after landing. Concern was that if they land far from expected landing site in Siberian taiga, it might take few days for rescue party to reach them, and they might need to defend themselves from predators like wolves.Peter Masiar 2017-08-10T22:46:45.337

@RussellBorogove Russia brings it's space capsules down on land. Normally the rescue crews would be there promptly but if they weren't for some reason there might actually be a need to defend against local wildlife. Given their mission profile a gun is sensible. My understanding is that some early US spacewalk missions carried a gun in case something went horribly wrong at the hatch. If the spacewalking astronaut became stuck in the hatch the one on board might have to shoot them and shove the body out so they could survive re-entry.Loren Pechtel 2017-08-11T05:18:00.427

@LorenPechtel I believe inability to reenter the spacecraft after EVA was a significant concern on Gemini 9A, to the point that they actually discussed before launch dragging a dead astronaut behind the spacecraft during atmospheric reentry, by way of an open hatch. I haven't looked in details, but Wikipedia puts the first US EVA at Gemini 4, making that the sixth US space flight that can possibly have included an EVA.Michael Kjörling 2017-08-11T09:05:59.567

@LorenPechtel The only gun carried on Gemini flights was a gas gun for maneuvering. You also completely missed the context of my remark.Russell Borogove 2017-08-11T15:34:33.507

@SF. and effects of prolonged exposure to microgravity were entirely unknown Simply not true. The Russians sent dogs on suborbital hops in early 50's, and later dogs on the early Sputniks. The Americans sent monkeys, fruit flies, etc. on suborbital and orbital flights before Alan Shepard. They monitored the dogs and monkeys in-flight. They ate food and survived for days. In Asif Siddiqi's books, the Soviets originally wanted the 1st spaceflight to last 1 day, then 1 of their dogs threw up in space, so changed it to 3 or 4 orbits, then just 1 orbit. Yuri Gagarin orbited 1x then came home.DrZ214 2017-08-12T21:25:02.500

So this is a good answer, but it really needs to add the bio-payloads of early spaceflight. That's how we got a good idea that prolonged exposure to mircrogravity is survivable.DrZ214 2017-08-12T21:25:44.463


One important note is that rocketry predates space travel - by a lot. MW 18014, the very first suborbital flight, (meaning the rocket flew to space, but didn't go fast enough to orbit the earth, so came back down) was in 1944. This rocket was designed to launch, fly in a specific trajectory, and land in a (relatively) specific location - and it worked. It didn't "do" anything, it had no practical payload. But it worked.

By 1944 our knowledge of physics/astrophysics was fairly advanced - we understood quite well that orbits are just a matter of going really fast around a celestial body. So, armed with a rocket that can fly into space, and knowledge of how orbits are made, spaceflight was a very natural next step.

It took quite a few tests like the one linked above to understand the engineering behind the first rockets, but for the most part rockets' trajectories, the physics of space, and the nature of vacuums were already known. It was just that these things were mostly known by theoretical scientists - not by engineers. So the first spaceflights were mostly just applying the theoretical understanding we already had of how an object might go from the ground to an orbit around earth.

It should be noted that while I make it sound simple, the actual engineering that went into making real spacecraft was very, very hard. To more directly answer your question about how humans found out how to deal with the unique challenges of space travel; we iterated for a long time. It took 13 years between MW 18014 and the successful flight of Sputnik 1, which was the first manmade object to orbit the Earth. 13 years is a long time to iterate on a design - even accounting for the chaotic political effects of the end of WW2 and the diffusion of German knowledge after it.

The way we learned about how to make a craft that could take a person into orbit was by actually sending objects up to space; rocket scientists were simply launching more and more satellites into the atmosphere to study the environment. By the time Yuri Gagarin became the first man in space in 1961 - a good four years after Sputnik - scientists already had a lot of experience sending rockets into orbit and dealing with the crazy effects of space travel.

tl;dr the way people learned how to deal with space was by shooting rockets into it until they figured out how it worked. Then they shot people into it.


Posted 2017-08-09T18:33:47.233

Reputation: 501

12+1 just for the last sentenceRedSonja 2017-08-10T10:28:00.057

9+1. I would just mention that they sent animals before they sent people.Martin Argerami 2017-08-10T13:30:20.313

3They actually launched beeping radios first. Then things with sensors. Then fruit flies, mice, dogs, monkeys and then humansInnovine 2017-08-11T09:45:38.387

1@Innovine Sputnik 1 had sensors. Pressure and temperature data was encoded into the signal.DrZ214 2017-08-12T21:27:57.203

@DrZ214 Sputnik was the first thing to achieve orbit. Rockets like the A4 - V-2 and R-1 went to space before thatInnovine 2017-08-13T07:35:26.493


I think this part of your question wasn't addressed very well so far:

How did they ever speculate no gravity and train astronauts according?

Russell Borogove already said a word on the second part so I'm gonna add something to the first part.

Actually there is quite a lot of gravity near Earth. For example gravity on the ISS is still around 0.89g meaning that it accelerates towards earth at 89% of the rate we have down on earth's surface.

The laws of gravity were known as early as 1687 from Newton's law of universal gravitation and Einstein's famous general theory of relativity gave additional insight in 1915 (See @vsz comment). So we knew that as soon as we shoot a rocket to ~400km above ground it would still accelerate downward at ~8.7 m/s^2 (increasing with reduced altitude). So in order to stay at constant height (=orbit) we need to account for that somehow. This means we knew it would be zero acceleration towards earth because that is exactly how we need to design the orbit in order to stay in space and not crash into the earth.

The problem now is: how to cancel out gravity. One explanation is that on observer on earth would see the space ship moving side ways so fast that it literally falls around earth (and this observer wouldn't say there's no acceleration on the space ship !). For an observer in the space ship we could calculate that (for a circular orbit) a centrifugal force is accelerating us away from earth at the same rate gravity attracts us which means there is an effective 0g acting on us but only in this rotating reference system.

TL;DR: Gravity still pulls us towards earth but we must counteract it in order to not fall down. On a space ship that would not rotate around earth but fire its engine to keep a constant low altitude we would feel almost as heavy as on earth.


Posted 2017-08-09T18:33:47.233

Reputation: 429

1The trick could be (and was) practically tested since 1930s with aircraft. The elliptical trajectory has the same Newton's physics; that it intersects the Earth is the only difference from the proper orbit. Hence aircraft shouldn't really follow it for too long.kubanczyk 2017-08-10T07:12:01.520

10"The laws of gravity were known due to Einstein's famous general theory of relativity starting 1915" - actually, the laws of gravity were known since the 1680s due to Newton, even if the underlying causes were not understood. You can get to orbit and even to the Moon without knowing about relativity.vsz 2017-08-10T09:38:20.543

@vsz Of course that's right. Einstein gave us better insight into what gravity is but that's at least not neccessary to calculate the speed at orbit. I will edit that in. Thanks for the heads up.Christoph 2017-08-10T10:01:24.127

4Thanks for this -- I didn't have the fortitude to tackle the "zero gravity"/"microgravity" bugaboo in my brief answer.Russell Borogove 2017-08-10T12:12:03.893

1Adding to what @vsz wrote, I recall reading somewhere (though I don't recall where off the top of my head) that when NASA ran the Earth-Moon transit using Newton's equations and using Einstein's equations, the difference was on the order of centimeters. Which of course is totally negligble over a 400 Mm distance.Michael Kjörling 2017-08-11T09:12:29.753

"Gravity still pulls us towards earth but we must counteract it in order to not fall down. "... just to be pedantic, there is no counteracting it, and anything in orbit is ALWAYS falling down. Since we're on a sphere, if you move horizontally the ground falls away from you. The trick is that in a circular orbit the spaceship is moving so fast horizontally that as it falls towards the center of the earth, the ground curves away from it at the same rate.Innovine 2017-08-11T09:39:51.220

@Innovine just to be pedantic: It depends on your reference frame. In a rotating reference frame we are not actually falling towards earth because of the centrifugal force which actually exists in this kind of reference frame. In this rotating reference frame the nearest point on ground always stays at the same spot and your velocity towards it is constant zero. The space ship doesn't move at all. The space ship is not moving on a circular trajectory it's moving in a straight line. In a plot you wouldn't have x/y axis you'd have distance+time axis.Christoph 2017-08-11T12:07:33.977

1You are not counteracting gravity in any reference frameInnovine 2017-08-11T12:23:30.780

1@Innovine call it however you want: there is a force acting in opposite direction of gravity with the same magnitude otherwise we would have movement on this axis in this reference frame. I know it doesn't fit how we usally observe space itself because we usally don't rotate but its absolutely correct. We don't have kartesian koordinates anymore but polar ones. This is getting a bit of topic so I suggest moving to the chat or making it a different question if your interested in my point of view on this :)Christoph 2017-08-11T12:41:15.463


By using science to make educated guesses, by performing tests on the ground as much as possible, then by attempting actual flights and learning what works and what doesn't, and then improving and taking on more ambitious goals. The other answers have gone into more detail but I want to share the following link which I think is extremely illustrative of the incremental nature of space flight and engineering.

It covers the many Soviet missions to Venus, starting with missions that went as far as the moon, then some more missions getting into interplanetary space, then ones that actually make it near to Venus, then ones that actually hit Venus, then missions which try to make it through the atmosphere, finally cumulating in a landing and a photo from the surface. It is long but an excellent read, and shows how each mission builds on the last, and become increasingly more complicated and ambitious.


Posted 2017-08-09T18:33:47.233

Reputation: 981