ISEE / ICE program

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ISEE C (ISEE 3) before the start in a test chamber

ISEE ( I nternational S un E arth E xplorer) was a space project of NASA and ESA (originally ESRO ) to research the solar wind and its interaction with the outer magnetosphere of the earth. It consisted of two satellites launched in 1977 (ISEE 1, 2) in very elliptical orbits and a space probe launched in 1978 ( ISEE 3 ) that orbited Lagrange point L1. In 1982, after the end of the planned mission life of 3 years, ISEE was 3 under the name ICE ( I nternational C ometary E xplorer ) to the comet Giacobini-Zinner and Halley sent. ISEE 1 and 2, however, continued their measurements in Earth orbit until they burned up in 1987. Although ISEE 1 and 3 were built in the USA and ISEE 2 on behalf of ESA, all three spacecraft had scientific experiments from the USA and the then ESA member states on board.

ISEE 1

ISEE 1 in space

ISEE 1 was built under the project name ISEE A by NASA's Goddard Space Flight Center. ISEE 1 was based (like ISEE 3) on the Explorer 43 , 47 and 50 satellites. ISEE 1 was a 16-sided prism- shaped satellite . The satellite body was 1.73 m in diameter and 1.61 m high. The upper and lower part of the jacket of ISEE 1 was covered with solar cells . Four fold-out booms were attached to the middle area, which, when folded, pointed upwards when the aircraft took off. The arms were offset by 90 ° to each other and unfolded into the equatorial plane of ISEE 1 so that they were perpendicular to the spin axis. Two brackets of equal length attached to opposite sides each supported a flat, rectangular box at each end. A boom offset by 90 ° carried a particularly interesting point, which consisted of a dumbbell lying in the equatorial plane of ISEE 1 with ends made of spherically bent, gold-colored wires . This was followed by an antenna whose cross-shaped rods were parallel to the spin axis. One rod lay in the equatorial plane of ISEE 1, the other pointed in the direction of the spin axis, another rod protruded away from ISEE 1 as an extension of the cantilever. The opposite boom, on the other hand, only supported a cube-shaped object at the end. In addition, ISEE 1 had four rod-shaped antennas that were extended out of the satellite body and pointed radially away from ISEE 1 in the equatorial plane. They were each offset by 45 ° to the arms. Two short, opposing antennas had spherical objects just before their end. In addition, two further long rod antennas from ISEE 1, offset by 90 ° to the short rod antennas, protruded from ISEE 1. The solar cell surface protruded beyond the top of ISEE 1. The top of ISEE 1 had a ring-shaped adapter around its center, on which the ISEE 2 satellite (still called ISEE B during take-off) was seated. The inside of the adapter had a hole through which, after the separation of ISEE 2, a mast with a discone antenna ran out at the top. The spin axis around which ISEE 1 rotated at 19.75 revolutions per minute for spin stabilization ran through this . This was perpendicular to the ecliptic . ISEE 1 had two transmitters with 2.5 watts each on board. Both broadcast in the S-band. Sender A sent scientific data in analogue and sender B digitally with PCM , but sender A could also send in PCM. The data rate was normally 4086 bit / s, but was normally increased to 16,384 bit / s every 5th cycle. ISEE 1 weighed 340 kg at launch, had 13 scientific instruments on board and its solar cells generated 175 watts at the start of operation and 131 watts after the completion of the primary mission of 3 years.

ISEE 2

ISEE 2 was approved by ESRO under the project name ISEE B in 1973 and built by the STAR consortium under the leadership of Dornier on behalf of ESRO, later ESA. ISEE 2 was a cylindrical satellite. The satellite body was 1.27 m in diameter and 1.20 m high. On top of it was a three foot mast with a discone antenna at the top. The spin axis ran through this, around which ISEE 2 rotated at 19.8 revolutions per minute for spin stabilization (and thus somewhat faster than ISEE 1). As with ISEE 1, the spin axis was perpendicular to the ecliptic . The upper 2/3 of the jacket of ISEE 2 was formed by 6480 2 × 2 cm silicon solar cells. These emitted 112 watts at the beginning in space and 65 watts at the end of their life (shortly before they burned up). Before the start, it was calculated that they would still deliver 72 watts at the end of the mission after three years. When ISEE 2 ran through the earth's shadow for 1 hour in perigee, it was supplied with 10 Ah in the first two years by a nickel-cadmium accumulator. After that, the accumulator failed as expected. The lower third of the coat was wrapped in black thermal insulation. Three 2.16 m long booms were attached to them, each offset by 120 °. These were folded up at takeoff and protruded over the satellite body. However, at the point where they passed the upper edge of the satellite body when folded up, all three had a kink from which they approached each other and almost met at the tips. This was necessary because the booms reached under the conical tip of the rocket's payload fairing . Spacers prevented this from touching the tips of the instruments. In the unfolded state, the booms stood on the spin axis of ISEE 2, whereby the kinks in the booms meant that they first led downwards at an angle and only then in one plane away from the satellite body. A dumbbell-shaped measuring device with ends made of spherically bent, gold-colored wires was attached to the end of a boom . The measuring device was parallel to the satellite surface. Another boom carried a measuring device at its tip, with short rods protruding on either side with tips at their ends. This measuring device was aligned parallel to the spin axis of ISEE 2. The top of the third mast carried a cylindrical object (approx. Twice as long as the diameter wide) as an extension that protruded from ISEE 2. There were also two roll-out wire antennas with a length of 15 m and two antennas for the electric field with a length of 31 m and 0.7 m. An intermediate floor was attached in the satellite body at the height of the dividing line between the jacket part covered with solar cells and the unoccupied jacket part. The satellite systems were housed on the intermediate floor and the scientific instruments on the underside. For position control and course corrections, ISEE 2 had two precision nozzles and four spindle nozzles. They used 10.7 kg of the unusual compressed gas Freon 14 ( tetrafluoromethane ). So that ISEE 2 itself did not influence the highly sensitive measuring instruments, the electromagnetic radiation from ISEE 2 was reduced to a minimum. In addition, the entire exterior of the satellite was electrically conductive, which kept potential differences below 1 volt, and the use of non-magnetic material meant that the direct current field on the magnetometer was weaker than 0.25 gamma . For measurement purposes, the distance in the apogee , where the magnetosphere is located, was changed between ISEE 1 and 2 between 10 and 5000 km. For this purpose, ISEE 2 was slightly accelerated or braked with its thrusters in or near the perigee . ISEE 2 had an adapter on the ground with which it was attached to ISEE 1 during takeoff. As a result, about 2/5 of the total height of ISEE 2 was covered by the protruding solar cells of ISEE 1 during take-off. ISEE 2 weighed 166 kg at launch and had eight scientific instruments on board.

ISEE 3

ISEE 3, after being renamed ICE, approaching the comet Giacobini-Zinner

ISEE 3 was built by the company Fairchild under the project name ISEE C on behalf of the Goddard Space Flight Center of NASA. ISEE 3 was based (like ISEE 1) on the Explorer 43 , 47 and 50 satellites. ISEE 3 was a probe in the form of a 16-sided prism . The probe body was 1.73 m in diameter and 1.61 m high. The upper and lower part of the jacket of ISEE 3 was covered with solar cells . Four fold-out booms were attached to the middle area, which, when folded up, pointed upwards in the starting configuration. The arms were offset by 90 ° to each other and unfolded into the equatorial plane of ISEE 3 so that they were perpendicular to the spin axis. Two cantilevers of equal length, attached on opposite sides, each had a rhombus parallel to the spin axis at their ends. A boom offset by 90 ° carried a particularly interesting tip, which consisted of a dumbbell lying in the equatorial plane of ISEE 3 with ends made of spherically bent gold-colored wires . This was followed by a measuring device parallel to the spin axis, from which short rods with tips at their ends protruded on both sides. The opposite boom, on the other hand, only supported a cube-shaped object at the end. In addition, ISEE 3 had four long rod-shaped antennas, which were extended from the satellite body and pointed radially away from ISEE 3 in the equatorial plane. They were each offset by 45 ° to the arms. They give ISEE 3 a diameter of 91 m. The solar cell surface protruded beyond the top of ISEE 3. A lattice mast is attached to the top of ISEE 3, which carries a rod antenna. An extendable rod antenna also protrudes from ISEE 3 at the bottom. The spin axis around which ISEE 3 rotates at 19.75 revolutions per minute for spin stabilization runs through these two antennas . The spin axis is perpendicular to the ecliptic . ISEE 3 had two transmitters with 5 watts each on board. Both broadcast in the S-band. The first transmitter sent scientific data with PCM , but the other transmitter could also send scientific data in PCM instead of ranging. Both transmitters could transmit through the same antenna at the same time, but using oppositely rotating polarizations. The data rate was changeable. At ISEE 3 in orbit around L1 and at the beginning of the ICE mission it was 2048 bit / s. At Giacobini-Zinner it was 1024 bit / s. After that, it dropped over 512 bps (September 12, 1985), 256 bps (May 1, 1987), 128 bps (January 24, 1989), to 64 bps (December 27, 1991). Scientific data could also be temporarily stored if it was collected faster than it could be transmitted. ISEE 3 weighed 469 kg at launch and had 12 scientific instruments on board and its solar cells generated 173 watts at the start of operation.

Missions

The ISSE spacecraft and their orbits

ISEE 1 and 2

ISEE A and ISEE B launched together under their project names on October 22, 1977 at 13:53 UTC from Launch Complex 17B of Cape Canaveral Air Force Station on board a Delta 2914 missile built by McDonnell Douglas into a highly elliptical orbit. It was the 135th launch of a Delta missile. Both the second stage and the third stage of the Delta rocket remained in various orbits of the earth as space debris . After separating, ISEE A and ISEE B took almost identical orbits and were renamed ISEE 1 and ISEE 2. ISEE 1, or Explorer 56, orbited the earth in a 337 to 137,904 km high orbit with an equatorial inclination of 28.95 °, and ISEE 2 orbited the earth in a 341 to 137,847 km high orbit with a 28.96 ° equatorial inclination. However, the gravity of the sun and moon led to periodic changes in the very eccentric orbits. In addition (as mentioned) the orbit of ISEE 2 was changed to change the distance between the satellites for different measurements. ISEE 1, 2 exceeded their planned lifespan of 3 years considerably and were still working when they entered the earth's atmosphere and burned up after almost 10 years on September 26, 1987 during the 1518th orbit. At ISEE 2, not a single scientific instrument had failed until then. The two satellites were controlled by the GSFC in orbit.

ISEE 3 / ICE

ISEE 3 orbit around L1 and its orbits with swing-bys on the moon and visits to comets at L2 as ICE

ISEE C launched under its project name on August 12, 1978 at 3:12 p.m. UTC from Launch Complex 17B of Cape Canaveral Air Force Station on board a Delta 2914 missile built by McDonnell Douglas in a path towards Lagrange point L1. It was the 144th launch of a Delta missile. After the start it was renamed ISEE 3 or Explorer 59. On November 20, 1978, it reached its planned Halo orbit around L1, becoming the first spacecraft to orbit a Lagrange point. Seen from the earth, this orbit was roughly in the shape of a 655,000 by 110,000 km ellipse, which ISEE 3 flew through in 177.86 days. The third stage of the delta rocket also followed ISEE 3 in the direction of L1 as space debris, and the second stage of the delta rocket also remained in an earth orbit as space debris. After ISEE 3 had reached its planned mission duration, the withdrawal of L1 began on June 10, 1982 with the ignition of the correction engines. She left L1 for the moon on September 1, 1982 and carried out a fly-by on him on October 16, 1982. After a thrust maneuver on November 21, 1982, and the subsequent deflection through the earth, ISEE 3 flew a loop orbit, reached the area of ​​L2 on February 8, 1983 and fell back towards the earth and moon. When passing the moon, on March 30, 1983, another fly-by took place, after which ISEE 3 orbited the earth several times in low orbits before it flew back towards the moon, where it did another swing-by on April 24, 1983 carried out and was thrown towards L2 again. This time she turned a loop further away from him and returned to the moon, where another swing-by took place on September 27, 1983. After another, relatively close loop around the earth, ISEE 3 entered another, elongated loop, the highest point of which it reached on November 23, 1983. Then she set course for the moon again, where she carried out the final fly-by on December 22, 1983. In doing so, it exceeded the escape speed of the earth-moon system and became an interplanetary probe. ISEE 3 was then renamed ICE and was on a trajectory to the comets Giacobini-Zinner and Halley . ICE reached Giacobini-Zinner on September 11, 1985 and passed its tail undamaged 7800 km behind its core, successfully taking measurements. Then it passed Halley's Comet on March 28, 1986 at a distance of 28 million km. From 1991 ICE was used to research the sun, together with ground-based observatories and sometimes together with the Ulysses solar probe . The ICE mission was ended on May 5, 1997, but the on-board transmitters were not switched off. In 2014 ICE came close to earth again. Space College employees had taken over control of ICE at the end of May 2014 with the approval of NASA and were planning to put it into earth orbit in order to continue using it there. When the course was to be corrected on July 8, 2014, the engines did not fire. It is believed that the pressurized nitrogen gas, which is necessary to press fuel into the engines, has been used up. As a result, ISEE-3 was unable to swing-by the moon on August 10, 2014, which would have re-entered Earth orbit. However, the instruments are still functional, so their data will continue to be received as long as possible while it moves away from Earth. In 2031 Template: future / in 5 yearsit will come close to Earth again.

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  1. ^ A History of the European Space Agency 1958 - 1987 Volume II
  2. ↑ a b satlist.nl: RAE Table of Earth Satellites 1977
  3. ↑ a b uiowa.edu: International Sun-Earth Explorer (ISEE) 1 and 2
  4. ↑ nasa.gov: ISEE 1NSSDC ID: 1977-102A
  5. ^ Esa.int: A History of the European Space Agency 1958-1987
  6. ↑ a b c d e Horst W. Köhler: Klipp und Klar: 100x Raumfahrt , Bibliographisches Institut, Mannheim, Vienna, Zurich 1977, ISBN 3-411-01707-4 , pp. 116/117
  7. ↑ a b nasa.gov: ISEE 2NSSDC / COSPAR ID: 1977-102B
  8. ↑ a b c d ISEE-2 ( Memento from October 16, 2006 in the Internet Archive )
  9. ^ Image from ISEE 2 at ESA
  10. ↑ a b satlist.nl: RAE Table of Earth Satellites 1978
  11. ↑ Keith Cowing: What ISEE-3 Really Looks Like Date: June 7, 2014; accessed on June 16, 2016
  12. ↑ a b c d nasa.gov: ISEE 3NSSDC ID: 1978-079A
  13. ↑ a b boeing.com: Boeing Launch Services - Mission Record ( Memento of October 29, 2012 in the Internet Archive )
  14. ^ Nasa.gov: ISEE 3 Maneuvers from Launch to Halo Orbit to Comet Exploration
  15. ↑ Nigel Calder : Beyond Halley. The exploration of tail stars by the space probes Giotto and Rosetta (original title: Giotto to the Comets ). Springer, Berlin, Heidelberg and New York 1994, ISBN 3-540-57585-5 , p. 119.
  16. ↑ Bernd Leitenberger: International Comet Explorer (ICE) , accessed on June 26, 2013
  17. ↑ Roman van Genabith: Is the ICE returning to earth to stay? , in raumfahrer.net, date: June 13, 2014, accessed June 16, 2014
  18. ↑ Failed engines: The sad flyby of the "Ice" probe. In: Spiegel Online . August 9, 2014, accessed June 9, 2018 .

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