Vostok 1

Vostok 1 (russian: link=no, Восток, ''East'' or '' Orient'' 1) was the first spaceflight of the Vostok programme and the first human orbital spaceflight in history. The Vostok 3KA space capsule was launched from Baikonur Cosmodrome on April 12, 1961, with Soviet cosmonaut Yuri Gagarin aboard, making him the first human to reach orbital velocity around the Earth and to complete a full orbit around the Earth.

The orbital spaceflight consisted of a single orbit around Earth which skimmed the upper atmosphere at at its lowest point. The flight took 108 minutes from launch to landing. Gagarin parachuted to the ground separately from his capsule after ejecting at altitude.

Background

The Space Race between the Soviet Union and the United States, the two Cold War superpowers, began just before the Soviet Union launched the world's first artificial satellite, Sputnik 1, in 1957. Both countries wanted to develop spaceflight technology quickly, particularly by launching the first successful human spaceflight. The Soviet Union secretly pursued the Vostok programme in competition with the United States' Project Mercury. Vostok launched several precursor uncrewed missions between May 1960 and March 1961, to test and develop the Vostok rocket family and space capsule. These missions had varied degrees of success, but the final two—Korabl-Sputnik 4 and Korabl-Sputnik 5—were complete successes, allowing the first crewed flight.

Pilot

:''See also Selection and training of the Vostok programme''
The Vostok 1 capsule was designed to carry a single cosmonaut. Yuri Gagarin, 27, was chosen as the prime pilot of Vostok 1, with Gherman Titov and Grigori Nelyubov as backups. These assignments were formally made on April 8, four days before the mission, but Gagarin had been a favourite among the cosmonaut candidates for at least several months.

The final decision of who would fly the mission relied heavily on the opinion of the head of cosmonaut training, Nikolai Kamanin. In an April 5 diary entry, Kamanin wrote that he was still undecided between Gagarin and Titov. "The only thing that keeps me from picking itovis the need to have the stronger person for the one day flight." Kamanin was referring to the second mission, Vostok 2, compared to the relatively short single-orbit mission of Vostok 1. When Gagarin and Titov were informed of the decision during a meeting on April 9, Gagarin was very happy, and Titov was disappointed. On April 10, this meeting was reenacted in front of television cameras, so there would be official footage of the event. This included an acceptance speech by Gagarin. As an indication of the level of secrecy involved, one of the other cosmonaut candidates, Alexei Leonov, later recalled that he did not know who was chosen for the mission until after the spaceflight had begun.Burgess and Hall, p.151

Preparations

Unlike later Vostok missions, there were no dedicated tracking ships available to receive signals from the spacecraft. Instead they relied on the network of ground stations, also called Command Points, to communicate with the spacecraft; all of these Command Points were located within the Soviet Union.

Because of weight constraints, there was no backup retrorocket engine. The spacecraft carried 13 days of provisions to allow for survival and natural orbital decay in the event the retrorockets failed.

The letters "СССР" were hand-painted onto Gagarin's helmet by engineer Gherman Lebedev during transfer to the launch site. As it had been less than a year since U2 pilot Gary Powers was shot down, Lebedev reasoned that without some country identification, there was a small chance the cosmonaut might be mistaken for a spy on landing.

Automatic control

The entire mission would be controlled by either automatic systems or by ground control. This was because medical staff and spacecraft engineers were unsure how a human might react to weightlessness, and therefore it was decided to lock the pilot's manual controls. In an unusual move, a code to unlock the controls was placed in an onboard envelope, for Gagarin's use in case of emergency. Prior to the flight, Kamanin and others told Gagarin the code (1-2-5) anyway.

April 11, 1961

At Baikonur Cosmodrome on the morning of April 11, 1961, the Vostok-K rocket, together with the attached ''Vostok 3KA'' space capsule, were transported several kilometers to the launch pad, in a horizontal position. Once they arrived at the launch pad, a quick examination of the booster was conducted by technicians to make sure everything was in order. When no visible problems were found, the booster was erected on LC-1.Burgess and Hall, p.150 At 10:00 (Moscow Time), Gagarin and Titov were given a final review of the flight plan. They were informed that launch was scheduled to occur the following day, at 09:07 Moscow Time. This time was chosen so that when the capsule started to fly over Africa, which was when the retrorockets would need to fire for reentry, the solar illumination would be ideal for the orientation system's sensors.Siddiqi, p.273

At 18:00, once various physiological readings had been taken, the doctors instructed the cosmonauts not to discuss the upcoming missions. That evening Gagarin and Titov relaxed by listening to music, playing pool, and chatting about their childhoods. At 21:50, both men were offered sleeping pills, to ensure a good night's sleep, but they both declined. Physicians had attached sensors to the cosmonauts, to monitor their condition throughout the night, and they believed that both had slept well. Gagarin's biographers Doran and Bizony say that neither Gagarin nor Titov slept that night. Chief Designer Sergei Korolev did not sleep that night, due to anxiety caused by the imminent spaceflight.

Gagarin statement before the mission

Before the mission, Gagarin made a statement to the press, addressed to the Soviet Union and to the whole world:

Flight

At 05:30 Moscow time, on the morning of April 12, 1961, both Gagarin and his backup Titov were woken. They were given breakfast, assisted into their spacesuits, and then were transported to the launch pad.Siddiqi, p.274 Gagarin entered the ''Vostok 1'' spacecraft, and at 07:10 local time (04:10 UTC), the radio communication system was turned on. Once Gagarin was in the spacecraft, his picture appeared on television screens in the launch control room from an onboard camera. Launch would not occur for another two hours, and during the time Gagarin chatted with the mission's main CapCom, as well as Chief Designer Sergei Korolev, Nikolai Kamanin, and a few others. Following a series of tests and checks, about forty minutes after Gagarin entered the spacecraft, its hatch was closed. Gagarin, however, reported that the hatch was not sealed properly, and technicians spent nearly an hour removing all the screws and sealing the hatch again.Siddiqi, p.275 According to a 2014 obituary, Vostok's chief designer, Oleg Ivanovsky, personally helped rebolt the hatch. There is some disagreement over whether the hatch was in fact not sealed correctly, as a more recent account stated the indication was false.

During this time Gagarin requested some music to be played over the radio. Korolev was reportedly suffering from chest pains and anxiety, as up to this point the Soviet space launch rate was 50% (12 out of 24 launches had failed). Two Vostoks had failed to reach orbit due to launch vehicle malfunctions and another two malfunctioned in orbit. Korolev was given a pill to calm him down. Gagarin, on the other hand, was described as calm; about half an hour before launch his pulse was recorded at 64 beats per minute.

Launch

* 06:07 UTC Launch occurred from the Baikonur Cosmodrome Site No.1. Korolev radioed, "Preliminary stage..... intermediate..... main..... lift off! We wish you a good flight. Everything is all right." Gagarin replied, "Let's go! (''Poyekhali!'')."
* 06:09 (T+ 119 s) The four strap-on boosters of the Vostok rocket used up the last of their propellant and dropped away from the core vehicle.
* 06:10 (T+ 156 s) The payload shroud covering Vostok 1 was released, uncovering a window at Gagarin's feet, with an optical orientation device (lit. "look" or "glance").
* 06:12 (T+ 300 s) The rocket core stage used up its propellant and fell away from the capsule and final rocket stage. The final rocket stage ignited.
* 06:13 Gagarin reported, "...the flight is continuing well. I can see the Earth. The visibility is good.... I almost see everything. There's a certain amount of space under cumulus cloud cover. I continue the flight, everything is good."
* 06:14 Vostok 1 passed over central Russia. Gagarin reported, "Everything is working very well. All systems are working. Let's keep going!"
* 06:15 Three minutes into the burn of the final rocket stage, Gagarin radioed, ", I can't hear you very well. I feel fine. I'm in good spirits. I'm continuing the flight..." Vostok 1 started to move out of radio range of the Baikonur ground station.
* 06:17 The rocket final stage shut down and Vostok 1 reached orbit. Ten seconds later the rocket separated from the capsule.

Time in orbit

* 06:18 UTC (T+ 676 s) Gagarin reported, "The craft is operating normally. I can see Earth in the view port of the . Everything is proceeding as planned". Vostok 1 moved on over Siberia as it passed over the Soviet Union.
* 06:21 Vostok 1 passed over the Kamchatka peninsula and out over the North Pacific Ocean. Gagarin radioed, "...the lights are on on the descent mode monitor. I'm feeling fine, and I'm in good spirits. Cockpit parameters: pressure 1; humidity 65; temperature 20; pressure in the compartment 1; first automatic 155; second automatic 155; pressure in the retro-rocket system 320 atmospheres...."
* 06:25 As Vostok 1 began its diagonal crossing of the Pacific Ocean from Kamchatka peninsula to the southern tip of South America, Gagarin requested information about his orbital parameters: "What can you tell me about the flight? What can you tell me?". The ground station at Khabarovsk didn't have his orbital parameters yet, and reported back, "There are no instructions from No. 20 ode name for Korolyov and the flight is proceeding normally." (Ground control did not know until 25 minutes after launch that a stable orbit had been achieved.)
* 06:31 Gagarin transmitted to the Khabarovsk ground station, "I feel splendid, very well, very well, very well. Give me some results on the flight!". At this time, Vostok 1 was nearing the VHF radio horizon for Khabarovsk, and they responded, "Repeat. I can't hear you very well". Gagarin transmitted again, "I feel very good. Give me your data on the flight!" Vostok 1 then passed out of VHF range of the Khabarovsk ground station.
* 06:37 Vostok 1 continued on its journey as the sun set over the North Pacific. Gagarin crossed into night, northwest of the Hawaiian Islands. Out of VHF range with ground stations, communications continued via HF radio.
* 06:46 Khabarovsk ground station sent the message "KK" via telegraph (on HF radio to Vostok 1). This was a code meaning, "Report the monitoring of commands," a request for Gagarin to report when the spacecraft automated descent system had received its instructions from ground control.
* 06:48 Vostok 1 crossed the equator at about 170° West in a southeast direction, and began crossing the South Pacific. Gagarin transmitted over HF radio, "I am transmitting the regular report message: 9 hours 48 minutes (Moscow Time), the flight is proceeding successfully. Spusk-1 is operating normally. The mobile index of the descent mode monitor is moving. Pressure in the cockpit is 1; humidity 65; temperature 20; pressure in the compartment 1.2 ... Manual 150; First automatic 155; second automatic 155; retro rocket system tanks 320 atmospheres. I feel fine...."
* 06:49 Gagarin reported he was on the night side of the Earth.
* 06:51 Gagarin reported the sun-seeking attitude control system was switched on; this oriented Vostok 1 for retrofire. The automatic/solar system was backed up by a manual/visual system; either one could operate the two redundant cold nitrogen gas thruster systems, each with of gas.
* 06:53 The Khabarovsk ground station sent Gagarin via HF radio, "By order of No. 33 (General Nikolai Kamanin), the transmitters have been switched on, and we are transmitting this: the flight is proceeding as planned and the orbit is as calculated." Vostok 1 was now known to be in a stable orbit; Gagarin acknowledged.
* 06:57 Vostok 1 was over the South Pacific between New Zealand and Chile as Gagarin radioed, "...I'm continuing the flight, and I'm over America. I transmitted the telegraph signal "ON".
* 07:00 Vostok 1 crossed the Strait of Magellan at the tip of South America. News of the Vostok 1 mission was broadcast on Radio Moscow.
* 07:04 Gagarin sent another spacecraft status message, similar to the one at 06:48. This was not received by ground stations.
* 07:09 Gagarin sent another spacecraft status message, also not received by ground stations.
* 07:10 Vostok 1 passed over the South Atlantic, into daylight again. At this point, retrofire is 15 minutes away.
* 07:13 Gagarin sent a fourth spacecraft status message; Moscow received this partial message: "I read you well. The flight is going...."
* 07:18 Gagarin sent another spacecraft status message, not received by ground stations.
* 07:23 Gagarin sent another spacecraft status message, not received by ground stations.

The automatic orientation system brought Vostok 1 into alignment for retrofire about 1 hour into the flight.

Reentry and landing

At 07:25 UTC, the spacecraft's automatic systems brought it into the required attitude (orientation) for the retrorocket firing, and shortly afterwards, the liquid-fueled engine fired for about 42 seconds over the west coast of Africa, near Angola, about uprange of the landing point. The orbit's perigee and apogee had been selected to cause reentry due to orbital decay within 13 days (the limit of the life support system function) in the event of retrorocket malfunction. However, the actual orbit differed from the planned and would not have allowed descent until 20 days.

Ten seconds after retrofire, commands were sent to separate the Vostok service module from the reentry module (code name "little ball" ()), but the equipment module unexpectedly remained attached to the reentry module by a bundle of wires. At around 07:35 UTC, the two parts of the spacecraft began reentry and went through strong gyrations as Vostok 1 neared Egypt. At this point the wires broke, the two modules separated, and the descent module settled into the proper reentry attitude. Gagarin telegraphed "Everything is OK" despite continuing gyrations; he later reported that he did not want to "make noise" as he had (correctly) reasoned that the gyrations did not endanger the mission (and were apparently caused by the spherical shape of the reentry module). As Gagarin continued his descent, he remained conscious as he experienced about 8 g during reentry. (Gagarin's own report states "over 10 g".)

At 07:55 UTC, when Vostok 1 was still from the ground, the hatch of the spacecraft was released, and two seconds later Gagarin was ejected. At altitude, the main parachute was deployed from the Vostok spacecraft.

Gagarin's parachute opened almost immediately, and about ten minutes later, at 08:05 UTC, Gagarin landed. Both he and the spacecraft landed via parachute south west of Engels