- Email: [email protected]
3.3. Instruments selected by ESA for the Huygens probe
J. 3. Pollack: Origin and Evolution (USA) D. F. Strobel: Aeronomy and Solar Wind Interaction (USA) 3. Facility Instrument Teams Titan Radar Mapper: C. Elachi, Team Leader (USA) Imaging Science Subsystem: Carolyn C. Porco, Team Leader (USA) Radio Science Subsystem: A. J. Kliore, Team Leader (USA) 4, Ion and Neutral Mass Spectrometer
A Facility Instrument Definition Team is to be appointed. A Science Team will be solicited through a separate Announcement of Opportunity. 5. Visual and Infrared Mapping Spectrometer This instrument has been approved as a Facility Instrument for the Investigation Accommodation Phase but will only be included in the payload if resources permit; R. H. Brown: Team Leader (USA).
3.3. INSTRUMENTS SELECTED BY ESA FOR THE HUYGENS PROBE’”
The reconnaissance and first exploration of the giant planets carried out so successfully by the Pioneer 11 (1979) Voyager 1 and Voyager 2 (1980-1981) fly-bys provided a wealth of information which has fundamentally changed our conceptions of the Jovian and Saturnian systems and the solar system as a whole. Many new questions have been raised, however, and the need has been underlined for a comparative study of each individual planetary system. Moreover, the importance has been recognized of studying the interactions between their various parts and with the solar system. In line with this, Jupiter will be investigated in great detail by the Galileo mission which was launched in 1988. The next logical step in gaining an understanding of the outer solar system is an equivalent mission to Saturn. A mission to Saturn and Titan, appropriately named Cassini after the discoverer of several of Saturn’s rings and satellite features, was proposed to ESA as a collaborative ES&NASA mission in November 1982. The Huygens probe to explore Titan was selected by ESA’s Science Programme Committee in November 1988. In the USA, the Cassini mission was given a new start authorization in October 1989. The Cassini mission aims at exploring the planet Saturn itself (atmosphere and interior), its magnetosphere, the icy satellites and the rings. Special attention will also be given to Titan, Saturn’s planet-sized moon, which is blanketed by a thick atmosphere and suggestive of the primitive Earth. @)From ESA News Release No. 49,s October 1990.
43
The mission consists of multiple (30) orbital tours through the Saturnian system by an orbiter, which will carry a Titan probe to be ejected upon arrival. This probe will enter and traverse the cloudy atmosphere of Titan down to the surface, which could be an ocean of methane, ethane and nitrogen, After completion of the probe mission, all the components of the Saturnian system, including Titan, will be studied remotely and in situ during the four-year lifetime of the mission. On its way to Saturn, Cassini will have an excellent opportunity to fly by several asteroids (only one or two will be selected) and also to perform cruise science during the eight-year interplanetary journey (Delta-Vega trajectory). ESA wilf provide the Huygens probe and give support to the operations, particularly of the probe. NASA will provide the Saturn orbiter, the iauncher and the operations. Both scientific communities wih share the science. An orbiter/probe mission is well suited to a division of effort between two partners and offers great .benefits to both the European and the American scientific communities. The Cassini spacecraft is proposed for launch by NASA in 1996 on a Titan IV-Centaur vehicle and to be operated by NASA. The flight trajectory requires approximately seven years from launch to Saturn orbital insertion. Once at the Saturnian system, the mission baseline lifetime is four years. The ESA Science Programme Committee, at its meeting on 17-18 September 1990 in Paris, approved the payload for the Huygens probe. The following lists the selected investigations and principal investigators. (a) Atmospheric Structure Instrument (ASI) to measure the temperature and pressure of the atmosphere, winds and turbulence, and the atmosphere electricity: M. Fulchi~o~ (Italy). (b) Gas Chromatog~ph Neutral Mass Spectrometer (GCMS) to measure the composition of the atmosphere during descent: H. Niemann (US). (c) Aerosol Collector and Pyrolyser (ACP) to sample aerosols suspended in the atmosphere, and analyse their composition: G. Israel (France) (d) Descent Imager-Spectral Radiometer (DISR) to make spectral measurements in several wavelengths from the uv to the near infrared and to take pictures of the clouds and of the ground: M. Tomasko (US). (e) Surface Science Package (SSP) to provide fundamental information on the state (liquid, semi-liquid, solid) of Titan’s surface at the point of touchdown: J. Zarnecki (UK). (f) Doppler Wind Experiment (DWE) to measure zonal wind characteristics with very high accuracy: M. Bird (FRG). The Science Programme Committee recommended that ESA and NASA do their best to accommodate two other instruments on the Huygens probe: Nephelometer (possibly a refurbished NASA Galileo nephelometer) to measure aerosol size and distribution Altimeter (ESA System Provided Capability) to measure the distance 44
between the probe and the ground during descent, and to provide information on surface roughness. In addition, the Science Programme Committee appointed three interdisciplinary scientists, who will be responsible for optimizing the scientific output from the probe, in the following disciplines: Titan Aeronomy: D. Gautier (France) Atmosphere-Surface Interactions: J. I. Lunine (US) Titan Organic Chemistry: F. Raulin (France).
3.4. FIRST RESULTS FROM THE HUBBLE
SPACE TELESCOPE’”
On 6 November 1990, ESA scientists announced the first results from the joint ESA-NASA Hubble Space Telescope. ESA’s Faint Object Camera has produced some dramatic results, despite problems with the telescope’s optical system. Both agencies are now looking at how the optical deficiencies can be improved by Shuttle astronauts on a mission planned for 1993. More than six months have passed since the launch of the Hubble Space Telescope, and more than four since its optical problems became apparent. At a meeting at ESTEC in the Netherlands at the end of October, astronomers from all over the world met to discuss the results so far and take stock of the optical problems. It was a very upbeat meeting, for it became abundantly clear that Hubble is still a unique ‘eye’ on the universe. According to ESA’s Dr D. Macchetto “the problem is not as fatal as many people feared? As ESA’s representative at the Space Telescope Science Institute in Baltimore, he is responsible for coordinating the observation programmes of astronomers. “We can do many things with the Hubble Space Telescope that are unique even today.” Above the turbulence of the Earth’s atmosphere, the Faint Object Camera is sensitive to uv radiation that is absorbed by the atmosphere and so cannot be seen from the Earth. Hubble Space Telescope has five scientific instruments consisting of two cameras, two spectrographs and a photometer. ESA’s Faint Object Camera can capture images too faint to be seen by the other camera, the US Wide Field Planetary Camera. It has been used to observe the planet Pluto, extremely faint galaxies, star clusters and objects at the furthest edges of the universe. “We have covered everything from one of the nearest planets to one of the most distant quasars” said Dr Macchetto. The Space Telescope was launched in late April of 1990 by the Space Shuttle Discovery. Released into orbit around the Earth, scientists and engineers began the long and involved process of checking out the telescope and its instruments. This is the normal procedure with telescopes on c4)From ESA Information
Note to the Press, 6 November
1990.
45
A Facility Instrument Definition Team is to be appointed. A Science Team will be solicited through a separate Announcement of Opportunity. 5. Visual and Infrared Mapping Spectrometer This instrument has been approved as a Facility Instrument for the Investigation Accommodation Phase but will only be included in the payload if resources permit; R. H. Brown: Team Leader (USA).
3.3. INSTRUMENTS SELECTED BY ESA FOR THE HUYGENS PROBE’”
The reconnaissance and first exploration of the giant planets carried out so successfully by the Pioneer 11 (1979) Voyager 1 and Voyager 2 (1980-1981) fly-bys provided a wealth of information which has fundamentally changed our conceptions of the Jovian and Saturnian systems and the solar system as a whole. Many new questions have been raised, however, and the need has been underlined for a comparative study of each individual planetary system. Moreover, the importance has been recognized of studying the interactions between their various parts and with the solar system. In line with this, Jupiter will be investigated in great detail by the Galileo mission which was launched in 1988. The next logical step in gaining an understanding of the outer solar system is an equivalent mission to Saturn. A mission to Saturn and Titan, appropriately named Cassini after the discoverer of several of Saturn’s rings and satellite features, was proposed to ESA as a collaborative ES&NASA mission in November 1982. The Huygens probe to explore Titan was selected by ESA’s Science Programme Committee in November 1988. In the USA, the Cassini mission was given a new start authorization in October 1989. The Cassini mission aims at exploring the planet Saturn itself (atmosphere and interior), its magnetosphere, the icy satellites and the rings. Special attention will also be given to Titan, Saturn’s planet-sized moon, which is blanketed by a thick atmosphere and suggestive of the primitive Earth. @)From ESA News Release No. 49,s October 1990.
43
The mission consists of multiple (30) orbital tours through the Saturnian system by an orbiter, which will carry a Titan probe to be ejected upon arrival. This probe will enter and traverse the cloudy atmosphere of Titan down to the surface, which could be an ocean of methane, ethane and nitrogen, After completion of the probe mission, all the components of the Saturnian system, including Titan, will be studied remotely and in situ during the four-year lifetime of the mission. On its way to Saturn, Cassini will have an excellent opportunity to fly by several asteroids (only one or two will be selected) and also to perform cruise science during the eight-year interplanetary journey (Delta-Vega trajectory). ESA wilf provide the Huygens probe and give support to the operations, particularly of the probe. NASA will provide the Saturn orbiter, the iauncher and the operations. Both scientific communities wih share the science. An orbiter/probe mission is well suited to a division of effort between two partners and offers great .benefits to both the European and the American scientific communities. The Cassini spacecraft is proposed for launch by NASA in 1996 on a Titan IV-Centaur vehicle and to be operated by NASA. The flight trajectory requires approximately seven years from launch to Saturn orbital insertion. Once at the Saturnian system, the mission baseline lifetime is four years. The ESA Science Programme Committee, at its meeting on 17-18 September 1990 in Paris, approved the payload for the Huygens probe. The following lists the selected investigations and principal investigators. (a) Atmospheric Structure Instrument (ASI) to measure the temperature and pressure of the atmosphere, winds and turbulence, and the atmosphere electricity: M. Fulchi~o~ (Italy). (b) Gas Chromatog~ph Neutral Mass Spectrometer (GCMS) to measure the composition of the atmosphere during descent: H. Niemann (US). (c) Aerosol Collector and Pyrolyser (ACP) to sample aerosols suspended in the atmosphere, and analyse their composition: G. Israel (France) (d) Descent Imager-Spectral Radiometer (DISR) to make spectral measurements in several wavelengths from the uv to the near infrared and to take pictures of the clouds and of the ground: M. Tomasko (US). (e) Surface Science Package (SSP) to provide fundamental information on the state (liquid, semi-liquid, solid) of Titan’s surface at the point of touchdown: J. Zarnecki (UK). (f) Doppler Wind Experiment (DWE) to measure zonal wind characteristics with very high accuracy: M. Bird (FRG). The Science Programme Committee recommended that ESA and NASA do their best to accommodate two other instruments on the Huygens probe: Nephelometer (possibly a refurbished NASA Galileo nephelometer) to measure aerosol size and distribution Altimeter (ESA System Provided Capability) to measure the distance 44
between the probe and the ground during descent, and to provide information on surface roughness. In addition, the Science Programme Committee appointed three interdisciplinary scientists, who will be responsible for optimizing the scientific output from the probe, in the following disciplines: Titan Aeronomy: D. Gautier (France) Atmosphere-Surface Interactions: J. I. Lunine (US) Titan Organic Chemistry: F. Raulin (France).
3.4. FIRST RESULTS FROM THE HUBBLE
SPACE TELESCOPE’”
On 6 November 1990, ESA scientists announced the first results from the joint ESA-NASA Hubble Space Telescope. ESA’s Faint Object Camera has produced some dramatic results, despite problems with the telescope’s optical system. Both agencies are now looking at how the optical deficiencies can be improved by Shuttle astronauts on a mission planned for 1993. More than six months have passed since the launch of the Hubble Space Telescope, and more than four since its optical problems became apparent. At a meeting at ESTEC in the Netherlands at the end of October, astronomers from all over the world met to discuss the results so far and take stock of the optical problems. It was a very upbeat meeting, for it became abundantly clear that Hubble is still a unique ‘eye’ on the universe. According to ESA’s Dr D. Macchetto “the problem is not as fatal as many people feared? As ESA’s representative at the Space Telescope Science Institute in Baltimore, he is responsible for coordinating the observation programmes of astronomers. “We can do many things with the Hubble Space Telescope that are unique even today.” Above the turbulence of the Earth’s atmosphere, the Faint Object Camera is sensitive to uv radiation that is absorbed by the atmosphere and so cannot be seen from the Earth. Hubble Space Telescope has five scientific instruments consisting of two cameras, two spectrographs and a photometer. ESA’s Faint Object Camera can capture images too faint to be seen by the other camera, the US Wide Field Planetary Camera. It has been used to observe the planet Pluto, extremely faint galaxies, star clusters and objects at the furthest edges of the universe. “We have covered everything from one of the nearest planets to one of the most distant quasars” said Dr Macchetto. The Space Telescope was launched in late April of 1990 by the Space Shuttle Discovery. Released into orbit around the Earth, scientists and engineers began the long and involved process of checking out the telescope and its instruments. This is the normal procedure with telescopes on c4)From ESA Information
Note to the Press, 6 November
1990.
45