How can Yuri Gagarin's Vostok 1 flight be considered to have been orbital, since he did not go all the way around Earth?

According to the Wikipedia article about Vostok 1, the launch site was near Tyuratam at 45°55′12.72″N 63°20′32.32″E, and the landing site was at 51.270682°N 45.99727°E. Other online sites are in general agreement with these locations.

So he landed 17 degrees west of the launch site. Sure sounds like a (long) sub-orbital flight.

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    "Orbital" means that you are at the right altitude and have the correct velocity to remain in orbit. It doesn't mean you physically have to sit there in orbit long enough to circumnavigate the Earth at least once. The place you end up landing isn't particularly relevant, either. – Lightness Races in Orbit Oct 9 '14 at 11:10
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    @LightnessRacesinOrbit The place you land isn't relevant only because "orbital" is not defined by "does at least one orbit". – David Richerby Oct 9 '14 at 12:38
  • @DavidRicherby: The place you land isn't relevant only because "orbital" is not defined by "does precisely an integer number of orbits and has a re-entry flight path precisely mirroring the original escape trajectory". – Lightness Races in Orbit Oct 9 '14 at 12:43
  • You guys are focusing on the wrong thing. David Ratti is mis-using the term "suborbital". So what? You need to read between the lines. What Ratti is questioning here is how Gagarin's flight qualifies him as the first person to orbit the Earth. – David Hammen Oct 9 '14 at 20:33
  • @DavidHammen: It has nothing to do with his misuse of the term "suborbital". It also does not mean that we're "focusing on the wrong thing" (otherwise you'd have seen my comment in answer form). I'm just pointing out a flaw in his expectations: "since he did not go all the way around Earth" is clearly false. – Lightness Races in Orbit Oct 10 '14 at 17:04
up vote 24 down vote accepted

Using the times of injection and retrofire in this diagram:

map of Vostok-1 flight path over Earth, with injection at 0617 UTC, and retrofire at 0725 UTC

and the orbit information from NASA, I get that Yuri did about 272° to 273° of a 360° orbit. So about 3/4ths of an orbit. I am not including the ten minutes it took to get from the launch pad to orbit as being in orbit, nor am I including the 30 minutes it took from the deorbit burn to landing as being in orbit.

Ok, he didn't complete one full orbit. So what? He was in orbit every second of that 3/4ths of an orbit. So, yes, Yuri did indeed go orbital. He didn't need to go 360° to make that claim.

I will posit a definition that you are in orbit, even if only for a portion of an orbit, if your calculated orbital lifetime is at least one orbit. For typical ballistic coefficients, that would be about 150 km. Yuri's orbit was 315 km x 169 km, with a much longer lifetime than one orbit. I calculate about a 19-day lifetime for that orbit and the (relatively high) ballistic coefficient of a Vostok spacecraft pointed into the wind.

It certainly wasn't a sub-orbital flight, as were the flights of Alan Shepard and Gus Grissom which never got close to achieving the speeds required for orbit.

  • Quite. As Mark points out, "it was in orbit". And that's that. "So, yes, Yuri did indeed go orbital. He didn't need to go 360° to make that claim." - it's just that simple. – Fattie Oct 12 '14 at 10:16
  • So he was in orbit even though he didn't complete an orbit. And the calculated 19-day expected orbital decay may explain why they decided to retrofire at the first available opportunity, rather than try for multiple orbits, since his life support was designed for a maximum of 10 days. – David Ratti Oct 21 '14 at 4:39
  • This is daft. A craft launched, encircled the body of the Earth for more than a complete orbit, and landed. Does it matter when rockets were firing? He was both orbital (in an orbit trajectory) and completed an orbit. If you're just struggling with the lines not joining up, consider the line for a GEO satellite; it is stationary above a point, or performs a figure-8 about it over the equator. The Earth turns. As David Hammen pointed out, look at the latitude (N/S), not the longitude; the line overlaps. The flight took nearly 2 hours, during which the Earth rotated 30 degrees under him. – Phil H Oct 21 '14 at 8:56
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    The Voyager aircraft took off, went all the way around the Earth, and landed. Did it orbit the Earth? No. – Mark Adler Oct 21 '14 at 15:17
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    Great diagram @Mark. It is interesting to notice that in the 1 hour 38 minutes of Gagarin's flight, the Earth turned 24.5 degrees. So while not in orbit all the way, he traveled 366.5 degrees around the center of the Earth. – andy256 Feb 5 '15 at 7:14

From Wikipedia's article on Vostok 1:

flightpath of Vostok 1

Path of Gagarin's complete orbit; the landing point is west of the takeoff point because of the eastward rotation of the Earth.

The flight was at least one orbit of the Earth (note the latitude of the landing is higher than the launch, see @DavidHammen's answer), and beyond that the mission involved firing retrorockets to leave orbit, so not only was it an orbit, the craft did attain orbital speed. Without retrorockets firing to reduce its orbital speed, it would complete many orbits around the Earth before its orbit would naturally decay due to atmospheric drag. The accomplishment of getting a human into orbit, round the Earth and back to the ground safely was there.

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    By the ground track, this is over one orbit. – David Hammen Oct 9 '14 at 19:56
  • Except that he didn't qualify under the terms being used to measure "first orbital flight" because he didn't return in his launch capsule. The Soviets had their astronauts bail out of the capsule and not land with it because the early capsules rarely slowed down enough to be human survivable on landing. Later capsules landing speeds were reduced to just causing severe injuries on landing. So the Soviets hid the fact that they didn't return to earth in their capsules so they'd qualify as "first in orbit" despite not following the exact terms to be internationally recognized. – StarPilot Oct 9 '14 at 21:46
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    He most certainly did qualify. People who claim Gagarin's flight didn't qualify don't know what they're talking about. The Fédération Aéronautique Internationale (FAI) is the organization that gets to decide what qualifies, and they decided that Gagarin's flight qualified. They did not retract that award after discovering that Gagarin parachuted to Earth. They instead struck the rule that astronauts/cosmonauts had to land in their vehicle. That rule makes sense for airplanes, but not so much for spacecraft. What makes sense is that the space explorer return to Earth, alive. – David Hammen Oct 10 '14 at 3:25
  • @DavidHammen: Agreed. The 'ground track' mention in the answer at present was a later edit by another user. Have edited it and pointed to your answer. – Phil H Oct 10 '14 at 10:04
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    If it had been known at the TIME, they'd have disqualified him. It was only discovered many years later, and by that time it was "common knowledge" in the world that he was the first man to orbit. The FAI did not want to look foolish by applying the rules for qualification and "changing history", so they changed the qualifications to match what the world knew. It was a political move on their part, just as it was a political move on the Soviets part to hide that he ejected from his craft because they couldn't land the capsule safely. – StarPilot Oct 13 '14 at 21:11

So he landed 17 degrees west of the launch site. Sure sounds like a (long) sub-orbital flight.

You are looking at the wrong parameter. The Earth rotated underneath the orbiting spacecraft during the 108 minute flight. A better parameter to look at is latitude. He launched to the northeast and landed 5.35 degrees north of the launch site. He passed the latitude of the launch site and then kept going for a bit. From launch to landing, his flight covered more than one orbit.

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    But orbital isn't defined as "did at least one orbit" so this is kind of moot anyway. – David Richerby Oct 9 '14 at 20:09
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    It's anything but moot. The OP misinterpreted what constitutes an orbit and used "sub-orbital" to mean "not quite an orbit". You will find a lot more historical references that say that Yuri Gagarin was the first person to orbit the Earth as opposed to saying that Yuri Gagarin was the first person to make an orbital flight. The comments and answers focused on the minor issue and missed the major issue, which is that this flight was an orbit. – David Hammen Oct 9 '14 at 20:30
  • So basically, if you looked at the flight path on a globe, instead of a flat map, it would be obvious that the flight is indeed slightly more than one orbit around the earth. – slebetman Oct 10 '14 at 12:42
  • True, but since we're picking nits here, his orbit really ended when he fired his retrorockets to deorbit. How far back was that? Maybe he didn't complete a 360° orbit from the time his launch vehicle finished its job to the time he finished the deorbit burn. I don't know. – Mark Adler Oct 10 '14 at 18:06
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    @MarkAdler - The key label on the ground track is "zážih brzdiaceho motora" which means "ignition of braking engine". The retrorockets fired just off the coast of Africa. Did Gagarin "orbit" the Earth? The Russians would of course say yes, but that might be a biased view. As far as the Fédération Aéronautique Internationale (FAI), the answer is yes. The answer is also "yes" as far as NASA is concerned. – David Hammen Oct 10 '14 at 18:32

Per the rules for the first complete orbit at the time, Gagarin would have to land further east than his launch point, and land inside his launch vehicle.

He didn't. Part of his 'heroism' on the part of the USSR was that he agreed to go along with the lie.

After the lie was revealed, the Federation Aeronautique changed the rules.

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    Do you have any sources for this? – Mark Omo Aug 28 at 1:37
  • Nobody argues that Gagarin completed a full orbit - all of the answers clearly show that he didn't. But this is irrelevant, because the question is whether he was in orbit at all, which he certainly was. – Przemek D Aug 28 at 6:48
  • The question did not ask for a complete orbit, it was about orbital or not. Gagarin was in orbit at a time when the USA were able to do only ballistic suborbital flights. The second human to orbit the Earth, German Titov did 17 orbits. He was the fourth person in space, counting suborbital voyages of US astronauts Alan Shepard and Gus Grissom. Titov was the first man to complete more than one full orbit. – Uwe Aug 28 at 16:54

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