STS-103 European Space Agency’s role in space telescope servicing mission Astronauts set for Hubble challenge European Space Agency astronauts Claude Nicollier and Jean-François Clervoy are key members of the crew of the Space Shuttle Discovery that will carry out a new round of repairs and maintenance on the Hubble Space Telescope. The mission’s main objective is to replace Hubble’s failing pointing system, which allows astronomers to aim precisely at stars, planets and other celestial targets. ubble, a joint NASA-ESA computer and insulation material Claude Nicollier (left) and Jean-François project, is one of the most during two spacewalks. He will also Shuttle mission will keep Hubble Clervoy of ESA (inset picture) discuss the Hsuccessful orbiting obser- become the first European to walk in Hubble servicing mission vatories ever, having provided a space from the Space Shuttle. wealth of new scientific data about on target for astronomers Jean-François Clervoy will operate hundreds of astronomical objects. the Shuttle’s robotic arm during operation of the robotic arm. fourth gyroscope fails. Mission facts It continues to conduct scientific demanding phases of the mission, observations but its pointing system Hubble was launched in 1990 with With less than three working Flight STS-103 including initial capture of the has begun to fail so the Space an expected orbital lifetime of 20 gyroscopes Hubble would remain satellite and during the spacewalks. Orbiter Discovery Shuttle is being launched on an years. ESA contributed a 15 safely in orbit but could not continue earlier than planned mission to Nicollier is on his fourth flight into percent share to its development with science observations. So, to Launch 6 December 1999 repair it. space. Among them he took part in and in return European astronomers ensure astronomers receive an 02.37 EST (08.37 CET) the first Hubble servicing mission in receive a guaranteed 15 percent uninterrupted service, the third Two of ESA’s most experienced Launch site Pad 39a, Kennedy Space Center, 1993, controlling the Shuttle’s share of observing time. In reality servicing mission has been split into astronauts will assume crucial roles Florida robotic arm while astronauts outside this has averaged 20 percent two – the first part now and the as part of a highly qualified performed repairs to the telescope. because of the high quality of second in mid-2001. Landing 15 December 1999 23.57 EST astronaut team. 16 December 1999 05.57 CET This time Clervoy, on his third flight, proposals from scientists in Europe. As well as replacing all the Claude Nicollier will help fit a new will have the lead role in the Landing site Kennedy Space Center, A third servicing mission had been telescope’s gyros the crew will also Florida scheduled for June 2000 but after install other equipment that has three of the telescope’s six either degraded in the harsh space Duration 10 days environment or can now be gyroscopes failed NASA officials Altitude 512 km decided not to risk waiting because replaced with more up-to-date three gyroscopes must be working technology. Inclination 28 degrees to meet the telescope’s very precise Discovery is scheduled for launch pointing requirements. NASA rules from the Kennedy Space Center in Crew members also dictate that a servicing mission December. should be considered before a Curtis Brown Commander (NASA) Scott Kelly European astronomers Pilot (NASA) on voyage of discovery Steven Smith Mission Specialist (NASA) joint NASA and ESA 15.9 m end-to-end and 4.3 m in Michael Foale project, the Hubble Space diameter at its widest point. Mission Specialist (NASA) Telescope has already A For European astronomers, and made some of the most dramatic John Grunsfeld scientists throughout the world, it is discoveries in the history of Mission Specialist (NASA) providing a rich cosmic harvest of astronomy. stunning pictures and new Claude Nicollier At its heart is a 2.4 m primary information – from the relatively Mission Specialist (ESA) mirror and a collection of five near planets in our own Solar Jean-François Clervoy science instruments that work across System to the most distant and Mission Specialist (ESA) the entire light spectrum, including unknown parts of the Universe. ESA’s Faint Object Camera. Manned servicing missions, to STS-103 websites replace faulty and obsolete parts with new or improved instruments, http://www.estec.esa.int/spaceflight are crucial to fulfilling its objective http://spaceflight.nasa.gov/shuttle of probing the farthest and faintest reaches of the cosmos for up to two http://sci.esa.int/hubble decades. http://www.stsci.edu The telescope, equivalent in size to The Hubble Space Telescope in the cargo bay of the Space Shuttle a double-decker bus, is roughly http://hubble.gsfc.nasa.gov during the last servicing mission cylindrical in shape and measures Sharp eyes above European astron the atmosphere ight from distant astronomical As a result the fine cosmic details the atmosphere with ‘eyes’ 10 times objects speeds through the become less clear because, to light, sharper than the largest ground- LUniverse on journeys taking our atmosphere is like a dirty lens. based telescopes. billions of years. So astronomers have always dreamt As a result Hubble, a joint NASA But on reaching Earth it has to pass of avoiding the problem by placing and ESA project, has already made through the atmosphere before a telescope in orbit. Hubble is the some of the most dramatic being received by ground-based answer to those dreams – it can discoveries in the history of telescopes. detect light before it is distorted by astronomy. A future space telescope urope could play a significant first time to look back through eons NASA and ESA are already role in the development of a of time to the very first stars and involved in NGST studies and E new space telescope to galaxies in the Universe. technology development activities, replace Hubble. A decision will be and the potential contribution of With an aperture of eight metres, taken next year on whether Europe, ESA will be decided upon in the NGST could also provide European through ESA, will participate in Spring of 2000. NASA wants to astronomers with a crucial NASA’s proposed Next Generation start formal development in 2003, complement to some of ESA’s Space Telescope (NGST). with a launch in 2008. planned future space projects, like NGST’s observing capabilities will FIRST (the Far InfraRed far surpass the reach of existing Submillimetre Telescope) and ground or space-based telescopes, Planck, a mission to study the providing the opportunity for the cosmic background radiation field. What is being replaced Credit: HST (NASA & ESA), WFPC2. Bruce Balick (University of Washington), Vincent Icke (Leiden University) and Garrelt Mellema (Stockholm University). Gyroscopes Cosmic collisions The Hubble Space Telescope’s gyros are the most accurate in the world, Observations carried out by Pieter extraordinarily stable and capable of detecting extremely small van Dokkum (Groningen and Leiden movements of the telescope – they have to be to keep HST precisely on Universities, The Netherlands) and target for long periods to collect the spectacular images. Marijn Franx (Leiden University) show the first direct images of As well as keeping Hubble stable, the gyros measure attitude when the telescope is changing its pointing from one celestial target to another. collisions between galaxies. The colliding galaxies reside in a so- There are six gyros on board and to provide enough information to called cluster of galaxies. Though control Hubble accurately three must operate simultaneously. collisions have been observed in But they have limited lifetimes. Only three of the six are working other clusters, this particular cluster properly and on this mission astronauts will replace all three double displays by far the largest number units leaving Hubble with six fresh gyros. ever seen. Fine Guidance Sensor To astronomers, the finding indicates This is the second in a series of refurbishments of Hubble’s three fine that, at least in some cases, massive guidance sensors which allow fine pointing and help keep the telescope galaxies form through collisions stable. The astronauts will be taking with them a renovated Fine between smaller ones. “It has been Guidance Sensor – the same unit that was returned on the last servicing a real surprise,” said team leader mission. The unit removed on this mission will be refurbished and Pieter van Dokkum. “Collisions had upgraded for re-use on the fourth servicing mission. never been observed before at this frequency. Many involve very New computer massive galaxies and the end result A radiation-rugged computer will replace Hubble’s now outdated main will be even more massive computer, dramatically increasing operational capabilities, reducing the galaxies.” burden of flight software maintenance and significantly cutting Previously, the evidence for the operational costs. The more advanced computer will run 20 times faster theories of galaxy formation through and provide six times as much onboard memory. collisions has been strong but Voltage/temperature improvement kits circumstantial. Thanks to Hubble a With age Hubble’s batteries become more susceptible to overheating if large number of galaxies have been they are overcharged. This kit will compensate by lowering the battery’s caught in the act. charge termination voltage. One kit will be installed for each of Credit: HST (NASA & ESA), WFPC2. Pieter van Dokkum (University of Groningen/Leiden), Marijn Franx (University of Leiden). Hubble’s six batteries. Spare S-band single access transmitter Discovery of a “naked” This will replace an aged and failed unit which will be removed, black hole returned to Earth and refurbished for a later flight. Interesting In 1997 Philippe Crane from the facts European Southern Observatory (ESO) Spare Solid State Recorder (SSR) at Garching, Germany discovered a The second of three tape recorders is being replaced by a high-capacity black hole peeping out over the edge ● Hubble has taken about solid state recorder, as was the first during the previous servicing of a swirling dusty disk.