An analysis of the flight of Vostok
of the article
The purpose of this
is to summarize new facts about the flight of Vostok to see if this new
information gives a new perspective on the flight. The location of both
the VHF and HF ground stations are now known. They can be compared with
in-flight voice contact transcripts. The text of the de-briefing of
after the flight is also available and provides interesting
I have tried to give a synoptic view of how the flight proceeded by
an annotated map of the ground track. An attempt to understand the
control system of Vostok is also made.
stations used for the flight
We now know the
locations of tracking stations and ground communications stations for the Vostok
flights and the Sputnik test flights proceeding them. The communications system with Vostok was based
VHF communications (143.625 MHz) but also on short-wave communications
strong transmitters belonging to the USSR Ministry of Communications. The
dependence on HF was necessary, because the Soviet Union did not yet
an ocean-going fleet of tracking ships. In particular for
the Vostok flight, the spacecraft flew over water from the
it left Soviet territory until retro-fire, so even if there had been
ground stations on foreign soil, they would not have helped, and the
of tracking ships therefore forced the use of HF. As we shall
below, the HF system worked, but perhaps not brilliantly. The HF frequencies used
the flight were 9.019 MHz and 20.006 MHz for AM voice and 19.995 MHz
the simple on-off keyed telemetry.
Part of our knowledge
the location of ground stations for the Vostok series is based on
Kamanin's diary (1) in which we can read
for 6 March 1961:
commission accepted my proposal about the organization of control
for the flight in Moscow (TsPUP), Tyura-Tam, Novosibirsk, Kolpashevo,
and Yelizovo (Kamchatka). Moscow will have shortwaves and VHF
with the spacecraft (if it makes more than one orbit), Tyura-Tam,
and Yelizovo will have VHF only, but Novosibirsk and Khabarovsk only
Radius of contact for shortwaves is 5000 km and 1500 km for VHF. These
radii thus far have not been practically checked and it is not yet
that communications will be reliable, especially during the phase
launch and orbital insertion. At every KP (Command Point) there will be
a KP chief, a communications officer, a cosmonaut, a doctor and a
of the Ministry of Communications. ..."
the table on the right the Sputnik-9 ground stations and the ground
for Vostok from (2) are shown:
The Vesna station in
has been added to the station network of Sputnik-9. The reason that we
know that the designation Vesna-2 stands for Khabarovsk is the
entry for the 16 August 1962 in the diary of N.P. Kamanin's (1):
his flight Nikolayev reported about the radio communications: The
worked well and was stable all the time. The best of all worked Vesna-2
(Khabarovsk), Vesna-1 and Vesna-6....."
map of the flight
In the figure below the
mentioned in (2) used during the Vostok
are shown. The coverage circle around Vesna-2 (Khabarovsk) corresponds
to the radius of contact (5000 km) that Soviet experts predicted before
the flight (See Kamanin's diary entry for 6 March
above). Of course short-waves was expected to work during most of
flight and four HF stations were transmitting to and listening for
To attract the attention of the cosmonaut the HF ground stations
various musical themes interrupted every 30 seconds by the call sign "VSN"
transmitted in Morse-code against the backdrop of the music. The
took turns in transmitting to the spacecraft as can be seen from the
||Kedr received by
||"Waves of the
signals heard from 0621
||Yes, at 0713
Since the music was
to give Gagarin a chance to judge the chances of communicating with a
ground station it seems that duplex was used.
below gives the landing time as officially announced in 1961. We now know that
touchdown of the descent module occurred at: 0748 UT and the touchdown of the
pilot occurred at 0753 UT (7)..
of events during orbital flight
with the launch site (Zarya-1)
During the launch phase
(Kedr) talks to Korolev and Kamanin up until 0615 UT. A Soviet
company released a record with about one
of noisy voice from Gagarin. It is possible to deduce that it is from
launch phase since Gagarin calls Zarya-1. Since the original recording
was "propaganda" meant to be published and since the record has no
notice, I take the liberty of reproducing the recording here
(168 kB mp3) (I have edited out the silent portions and filtered the
recording for better audibility).
Chris van den Berg has
a translation and I have tried to correlate his translation to the
in (2) and (3).
understood that. I heard in the .......(unclear) ... worked
very well. My general state is excellent. All is working well. I hear
loud and clear."
.. the flight is continuing well. I can see the earth. The visibility
good. ... I almost see everything. There's a certain amount of
under cumulus cloud cover. I continue the flight, everything is
is working very well. All systems are working. Let's keep going!"
Zarya-1, I can't hear you very well. I fel fine. I'm in good spirits.
continuing the flight....."
with Kolpashevo (Zarya-2)
At 0617, Zarya-2
calls Kedr. Gagarin gives a routine report:"
The craft is operating normally. I can see Earth in the view port of
Vzor. Everything is proceeding as planned". Four minutes
later he essentially repeats the report and then contact with Zarya-2
lost shortly after 0621 UT. Then followed a three minute gap in VHF
picks up message
At 0621 UT, shortly after
of VHF contact, the Vesna station at Khabarovsk picks up a rather
report from Gagarin:
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
155; pressure in the retro-rocket system 320 atmospheres...."
with Yelizovo (Zarya-3)
VHF contact was restored
Zarya-3 (Yelizovo) at 0625 UT. Gagarin asks for information about the
can you tell me about the flight? What can you tell me?"Obviously
he is interested in what the telemetry shows about the status of the
and probably also about the orbit. The radio operator at Zarya-3 has
much to tell Gagarin:
"There are no instructions
from No. 20 (Korolev), and the flight is proceeding normally".Gagarin
then says "Tell me your data on the
still worrying about his craft, but interjects a greeting to fellow
Leonov, who was at Yelizovo:
"My regards to Blondin
is interesting that in the middle of this contact, at 0626 UT, Vostok
above the horizon at the U.S. ELINT station on Shemya where a readout
the TV images of Gagarin took place (see article "TV
from Vostok") (5). TV transmissions
Vostok are not mentioned in (2), (3),
or (4), except that in (3)
Gagarin mentions that he has switched on the TV lights. However, in (6)
it is mentioned that "in additon, a television camera has been
in the cockpit of the satellite craft so taht the cosmonaut can be
when the craft is within line-of-sight from the Soviet Union....". (The
picture on the right is a heavily retouched TV picture of Gherman Titov
from onboard Vostok-2.)
Gagarin keeps asking
data on the flight as his craft approaches the horizon at Zarya-3, but
the ground has difficulty hearing him: "I
splendid, very well, very well, very well. Give me some results on the
flight!" Zarya-3 replies: "Repeat.
I can't hear you very well". Gagarin comes back to say: "I
feel very good. Give me your data on the flight!" After
that VHF contact is lost with Vostok.
communications beyond line-of-sight
With the spacecraft out of
of VHF stations Nikolai Kamanin ordered the Khabarovsk Vesna short-wave
station to send the telegraph message "KK"
which meant "Report the monitoring of
This order to Gagarin was broadcast at 0646 UT. The commands referred
were probably the descent system commands. Gagarin did not reply
but at 0647-0648 UT he read this report, which was picked up in
am transmitting the regular report message: 9 hours 48 minutes (Moscow
Time), the flight is proceeding successfully. Spusk-1 is operating
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
system tanks 320 atmospheres. I feel fine...".
Shortly after he
entering eclipse (0649 UT) and not hearing the ground, but Vesna heard
him. At 0651 UT Gagarin reported that the sun-seeking attitude control
system had been switched on and Vesna picked up that message also.
Finally, at 0653 UT
transmits the message that Gagarin has been waiting for:
order of No.33 (Kamanin) the transmitters have been switched on, and we
are transmitting this: the flight is proceeding as planned and the
is as calculated." This
message is repeated a minute later and Gagarin acknowledges the message.
The final message
up by Khabarovsk at 0657 UT is slightly erroneous as to the whereabouts
of the spacecraft:
continuing the flight, and I'm over America. I transmitted the
signal "ON" (The
equipment is operating normally)
Actually Vostok was
the South Pacific approaching the southern tip of South America.....
his reports at 0704 UT, 0709:15 UT, 0718 UT, and 0723 UT, but they were
not picked up by ground stations. Only a brief transmission was picked
up in Moscow at 0713 UT: "I
read you well. The flight is going...".
operation of the attitude control system
tried to find description of how the Vostok attitude control system and
how the orientation for retrofire was performed. The accounts in (3)
and (4) often refer to the
attitude control system. Interestingly, it was switched on at 0651 UT,
16 minutes before exit into sunlight. To me this seems to indicate that
the spacecraft first found the local vertical and then found the sun
exit into sunlight. Exactly how the earth-sun acquisition was made is
However, the sun sensor must have had the capability to be
with an offset angle depending on the position of the sun in relation
the orbital plane and the desired retrorocket thrust vector direction.
The figure below shows that the sun vector was quite far from the
possibility would have been to use ionic
sensors to provide a yaw reference. In such a case the sun would
have been needed as an attitude reference. However, I think that the
sensors were first flown on Voskhod-1 and its test flights. Therefore,
Vostok was forced to rely on an an earth-sun attitude reference system.
N.P., Diaries, entries for 6, 9, 23 March 1961 and 16 August 1962.
Translated by Chris van den Berg.
of Communications between Gagarin and Flight Control, Izvestiya TsK
No. 5, 1991, pp 105-114
of Gagarin's In-Flight Tape Recording, Izvestiya TsK KPSS, No. 5, 1991,
Report of Gagarin to State Commission, Izvestiya TsK KPSS, No. 5, 1991,
Henry G. "Snooping on Space Pictures", Studies in Intelligence, RG
263, Entry 400, "Articles From Studies in Intelligence,
Archives and Records Administration.
of D.F. Ustinov, K.N. Rudnev, V.D. Kalmykov, and other to the CPSU
Committee on the status of the first manned spaceflight, dated 30 March
1961, published in Izvestiya TsK KPSS, No. 5, 1991, pp 101-105.
- According to
information relayed by Igor Lissov in April 2011.
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