Helios (probe)

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Helios

Helios probe during a test
NSSDC ID A: 1974-097A
B: 1976-003A
Mission goal Sun
Client National Aeronautics and Space AdministrationNASA NASA , DFVLRGermanyGermany
Launcher Titan-IIIE / Centaur
construction
Takeoff mass 370 kg
Course of the mission
Start date A: December 10, 1974 at
7:11 am B: January 15, 1976 at 5:34 am
launch pad CCAFS , LC-41
End date 1992
 
 08/20/1974/76 Start on Cape Canaveral
 
 1977/78 Entry into Venus-like solar orbits
 
 06/16/1986 End of scientific activities
Titan 3E Centaur launcher with the Helios 1 spacecraft (CCAFS, 1974)

The Helios space probes were a joint project of the Federal Republic of Germany and the United States of America to research the sun . Two spacecraft were launched. The first started at the end of 1974 and the second at the beginning of 1976.

mission

In 1966, Federal Chancellor Ludwig Erhard and US President Lyndon B. Johnson reached an agreement on a joint, ambitious planetary mission. What kind of mission this would be should be determined by the space agencies DFVLR and NASA . On June 10, 1969, the Mission Treaty was formally ratified. It was agreed to build a pair of probes that would examine the space between the sun and earth more closely and thereby come closer to the sun than any previous probe.

The two probes Helios 1 and Helios 2 were a joint project of the Federal Republic of Germany (approx. 70%) and the USA (approx. 30%). Germany built the probes and the US provided the launch vehicles and support from the Deep Space Network . The two probes were named after the Greek sun god Helios . The Effelsberg radio telescope and the 30-meter antenna of the Weilheim satellite ground station took part in monitoring the probes.

course

Orbits of Helios 1 and Helios 2
  • Helios 1 launched under its project name Helios A on December 10, 1974 on a Titan IIIE Centaur rocket from Launch Complex 41 on Cape Canaveral . The probe reached a solar orbit with a minimum solar distance of 46.5 million kilometers (0.31 AU), which corresponds to the closest distance of the innermost planet Mercury to the sun. The point of the orbit of Helios 1 furthest from the sun corresponds roughly to the distance between the earth and the sun. Contact with Helios 1 was lost on March 16, 1986.
  • Helios 2 started under its project name Helios B on January 15, 1976, also on a Titan Centaur rocket from the same ramp. It came within 43.5 million kilometers (0.29 AU) of the sun. The Helios 2 mission ended in December 1981.

Structure of the probes

Helios 1 and 2 (also called Helios A and B) were probes with the shape of an oversized spool of thread. The maximum width was 2.77 m, the minimum 1.75 m. The height of the probe body was 2.12 m and with the antenna mast extended 4.23 m. The rectangular reflector of the high gain antenna was located behind the lower part of the mast . Above that there was a low gain antenna on the mast and a dipole antenna on the top of the mast. The takeoff weight was 371 and 374 kg, respectively.

The biggest challenge was regulating the temperature. 50% of the surface was covered with reflective reflectors, which reflected the solar radiation. In addition, powerful radiators were attached to the two front sides. In addition, the shape minimized the radiation and the probes were also very well insulated. Due to the rapid rotation of one revolution per second, the surface was only briefly exposed to the sun and the heat was evenly distributed.

After Helios 1 had lower temperatures on board than planned despite a minimal distance of 46.2 million km from the sun, its sister probe Helios 2 was transported to an orbit even closer to the sun, in which it is up to 43.4 million km to the sun approximated.

Of the ten experiments with a total weight of 73.2 and 76.5 kg respectively, seven came from Germany and three from the USA, depending on the financial contribution of the federal states.

The experiments concerned three questions:

Data and information

  • Helios 1 was the first spacecraft that did not come from the USSR or the USA .
  • With Helios 1, the Titan Centaur rocket was used successfully for the first time.
  • The two Helios probes each weighed around 370 kg and had 10 scientific experiments on board.
  • The two probes were built for a service life of 18 months, but lasted over 11 years (Helios 1) and 6 years (Helios 2).
  • The probes rotated continuously around the cylinder axis so that a temperature of 20 ° C could be maintained inside. The outer shell heated up to 300 ° C.
  • The Helios program cost about 260 million US dollars .
  • A reserve copy is on display in the Deutsches Museum in Munich .
  • The probes held the space probe speed record of 252,792 km / h (70.22 km / s) relative to the Sun until November 6, 2018, when they were surpassed by the Parker Solar Probe .

See also

literature

  • Niklas Reinke: History of the German space policy. Concepts, influencing factors and interdependencies: 1923-2002. Munich 2004, ISBN 3-486-56842-6

Web links

Commons : Helios  - collection of images, videos and audio files

Individual evidence

  1. ↑ Hermann Hagn, Gerhard Metz, Hanspeter Kuhlen, Dominik Kuhlen: The 30-meter deep space antenna at DLR-GESOC in Weilheim / Obb. as a ground station for phase 5 mission Mars . ( amsat-dl.org [PDF]). The 30-meter deep space antenna at DLR-GESOC in Weilheim / Obb. as a ground station for phase 5 mission Mars ( memento from December 26, 2005 in the Internet Archive )