November 1995
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| November 1995 |
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Immediately following the 7th UKSEDS Student Space Conference, at University College London, both STAAR Research and the Glasgow Discovery Club affiliated to UKSEDS. AspireSpace also announced that they would be following suit.
Informal contact has been established by the new committee of UKSEDS with both NEXUS, the succesful student division of the Institute of Physics, and with the Royal College of Art. It is hoped to build on these contacts during 1996, with the establishment of links between UKSEDS and both these, and other organisations.
Application forms will shortly be available for SURF-96, the exciting American undergraduate space study programme, Each year a number of UKSEDS members succesfully apply to attend SURF, and it is hoped that this will continue for 1996. The SURF programme takes place during the summer vacation.
For more details on SURF, please contact UKSEDS at the UKSEDS central address
On the 14th of November, following a one day delay, the Space Shuttle Atlantis blasted off, for the second mission to the Russian MIR space station. Unlike the previous Space Shuttle / MIR docking mission, STS-71, this mission, STS-74 saw the addition of a new docking module to MIR. The 5 metre long module was carried up in the Space Shuttle payload bay, to be attached to the Kristall module on MIR. The addition of this docking port provides enough clearance for the Space Shuttle to dock safely with MIR, without having to move the location of the Kristall module each time. The Space Shuttle also delivered extra solar panels to the MIR station
The STS-74 / MIR mission will include Russians, Americans, a German, and a Canadian. With Thomas Reiter of Germany being one of the cosmonauts on the EuroMIR '95 mission, and the Canadian being one of the STS-74 astronauts.
Details on the EuroMIR 95 mission, can be obtained on the following world wide web pages: EuroMIR-95
On the 7th of December, the Galileo descent probe will plunge into the Jovian atmosphere. Thus will begin the main mission of Galileo.The descent probe was released from the Galileo orbiter in July 1995, allowing the orbiter to make trajectory changes to prevent it from following the probe into the Jovian atmopshere.
Following the disastrous affair of the High Gain antenna which failed to open, two more recent scares have concerned the onboard tape recorder, which has been r temperamental, and the propulsion system which looked for a while, as if it might do a Mars Observer, and go bang. It is hoped that these problems will be rectified in time for the main mission to start in December.
Despite these setbacks, the Galileo mission has been very succesful. As well as Earth- Moon fly-bys, In 1991, Galileo made the first asteroid fly by, of asteroid 251 Gaspra. It followed up with another asteroid fly-by in 1993, of asteroid 248 Ida. During the Ida encounter, Galileo also discovered that Ida had a small moon, since named "Dactyl". The first time a moon had been discovered around an asteroid.
For more details on the Galileo mission, check the world wide web pages at: Galileo
Proving once again, its capacity to provide breathtaking imagery of the stars, the Hubble Space Telescope has recently returned pictures of Star formation, showing dust clouds condensing to form protostars.
On November the 17th, the European Space Agency (ESA) Infrared Space Observatory (ISO) was launched on an Ariane IV launcher, for an eighteen month mission, to examine the Universe in the infrared region of the spectrum. With major involvement from U.K. institutions such as the Rutherford Appleton Laboratory, Queen Mary and Westfield College, University of London and Imperial College, University of London, ISO will undoubtedly vastly increase our insight into the infra-red Universe, adding to the 200,000 new infrared objects discovered by the IRAS satellite over a decade earlier in 1983. ISO is designed to examine the sources of infrared radiation in great detail. It is equipped with a camera, an imaging photopolarimeter and two spectrometers. The instruments will be cooled using a tank of 2000 litres of superfluid Helium.
Dramatic new pictures from NASA's Hubble Space Telescope show newborn stars emerging from dense, compact pockets of interstellar gas called evaporating gaseous globules (EGGs). Hubble found the "EGGs," appropriately enough, in the Eagle nebula, a nearby star-forming region 7,000 light-years away in the constellation Serpens.
"For a long time astronomers have speculated about what processes control the sizes of stars -- about why stars are the sizes that they are," says Jeff Hester of Arizona State University, Tempe. "Now we seem to be watching at least one such process at work right in front of our eyes."
Pictures taken by Hester and co-investigators with Hubble's Wide Field Planetary Camera-2 (WFPC2) resolve the EGGs at the tip of finger-like features protruding from monstrous columns of cold gas in the Eagle nebula (also called M16 -- 16th object in the Messier column). The columns -- dubbed "elephant trunks" -- protrude from the wall of a vast cloud of molecular hydrogen, like stalagmites rising above the floor of a cavern. Inside the gaseous towers, which are light-years long, the interstellar gas is dense enough to collapse under its own weight, forming young stars that continue to grow as they accumulate more and more mass from their surroundings.
Hubble gives a clear look at what happens as a torrent of ultraviolet light from nearby young, hot stars heats the gas along the surface of the pillars, "boiling it away" into interstellar space -- a process called "photoevaporation." The Hubble pictures show photoevaporating gas as ghostly streamers flowing away from the columns. But not all of the gas boils off at the same rate. The EGGs, which are denser than their surroundings, are left behind after the gas around them is gone.
"It's a bit like a wind storm in the desert," said Hester. "As the wind blows away the lighter sand, heavier rocks buried in the sand are uncovered. But in M16, instead of rocks, the ultraviolet light is uncovering the denser egg-like globules of gas that surround stars that were forming inside the gigantic gas columns."
Some EGGs appear as nothing but tiny bumps on the surface of the columns. Others have been uncovered more completely, and now resemble "fingers" of gas protruding from the larger cloud. (The fingers are gas that has been protected from photoevaporation by the shadows of the EGGs). Some EGGs have pinched off completely from the larger column from which they emerged, and now look like teardrops in space.
By stringing together these pictures of EGGs caught at different stages of being uncovered, Hester and his colleagues from the Wide Field and Planetary Camera Investigation Definition Team are getting an unprecedented look at how stars and their surroundings appear before they are truly stars.
"This is the first time that we have actually seen the process of forming stars being uncovered by photoevaporation," Hester emphasized. "In some ways it seems more like archaeology than astronomy. The ultraviolet light from nearby stars does the digging for us, and we study what is unearthed."
"In a few cases we can see the stars in the EGGs directly in the WFPC2 images," says Hester. "As soon as the star in an EGG is exposed, the object looks something like an ice cream cone, with a newly uncovered star playing the role of the cherry on top."
Ultimately, photoevaporation inhibits the further growth of the embryonic stars by dispersing the cloud of gas they were "feeding" from. "We believe that the stars in M16 were continuing to grow as more and more gas fell onto them, right up until the moment that they were cut off from that surrounding material by photoevaporation," said Hester.
This process is markedly different from the process that governs the sizes of stars forming in isolation. Some astronomers believe that, left to its own devices, a star will continue to grow until it nears the point where nuclear fusion begins in its interior. When this happens, the star begins to blow a strong "wind" that clears away the residual material. Hubble has imaged this process in detail in so- called Herbig-Haro objects.
Hester also speculated that photoevaporation might actually inhibit the formation of planets around such stars. "It is not at all clear from the new data that the stars in M16 have reached the point where they have formed the disks that go on to become solar systems," said Hester, "and if these disks haven't formed yet, they never will."
Hester plans to use Hubble's high resolution to probe other nearby star-forming regions to look for similar structures. "Discoveries about the nature of the M16 EGGs might lead astronomers to rethink some of their ideas about the environments of stars forming in other regions, such as the Orion Nebula," he predicted.
The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency.
Three images depicting the dramatic pillars in the Eagle Nebula and "EGGs" are available to news media representatives by calling the Headquarters Imaging Branch at 202/358-1900. NASA Photo Numbers are: Color B&W M16 3 Pillars 95-HC-631 95-H-643 M16 1 Pillar 95-HC-632 95-H-644 M16 B&W Detail 95-H-645
Image files in GIF and JPEG format and captions may be accessed on the Internet via anonymous ftp from ftp.stsci.edu in /pubinfo: M16 3 Pillars gif/M16Full.gif jpeg/M16Full.jpg M16 1 Pillar gif/M16WF2.gif jpeg/M16WF2.jpg M16 B&W Detail gif/M16HaBW.gif jpeg/M16HaBW.jpg
Higher resolution versions (300 dpi JPEG) of the release photographs will be available temporarily in /pubinfo/hrtemp: 95-44a.jpg, 95-44b.jpg and 95-44c.jpg.
GIF and JPEG images, captions and press release text are available via World Wide Web at URL
A satellite payload designed and built by college students was successfully launched Saturday from Vandenberg Air Force Base, CA, onboard a NASA launch vehicle.
Now in orbit 746 miles above Earth, SURFSat-1 rode piggy-back on the upper stage launch vehicle for Radarsat, a Canadian satellite. SURFsat carries low-power radio transmitters which send in three microwave bands to NASA tracking stations. SURFSat-1 is used for deep space communication research and development, and also will be used to test a new set of Earth orbit tracking stations.
The student project was initiated at NASA's Jet Propulsion Laboratory, Pasadena, CA, in 1987 as part of the Summer Undergraduate Research Fellowship (SURF) program of the California Institute of Technology. The first objective was to design, build, launch and operate a low-cost, low-power vehicle to be used to test the performance of space communication in the new Ka-band, at frequencies of approximately 32 Gigahertz.
NASA's Deep Space Network is being upgraded to support higher frequency Ka-band transmissions from planetary spacecraft. This will permit the use of more channels compared to current X-band deep space links. One purpose of the SURFSat payload is to test how Earth's atmosphere affects Ka-band signals. Despite the new band's potential advantages for deep space communication, it is expected to be affected more by weather than X-band transmissions.
SURFSat-1 carries a pair of beacons, one in each of the two bands, which imitate a probe far out in deep space by transmitting at only a thousandths of a watt of power. As the satellite passes overhead, engineers can collect data allowing them to compare performance in each of the two bands over a wide range of elevation angles and weather conditions.
SURFSat-1 also carries an experiment to test ground stations supporting NASA's new Space Very Long Baseline Interferometry project. The stations will communicate with a spacecraft to be launched by Japan that will make radio astronomy studies of quasars and other objects at the edge of the universe.
When the project began in 1987, six Caltech students were chosen to begin SURFSat. Each summer, a new group of undergraduates took over. Through 1994, a total of 61 students, including those from other colleges, have participated. JPL provided a dedicated laboratory for the work and a test range and a lab at the Goldstone Deep Space Communications Complex. Three former SURF students are now full-time employees at JPL.
The original idea was to build a simple spacecraft appropriate to a student project and give students an opportunity to work with space technology. The solar-powered satellite consists of two aluminum boxes, about 12 inches by 12 inches by 16 inches permanently bolted to the guidance section of a NASA Delta II second stage booster. Shortly after launch it was separated from the primary payload, Radarsat, and moved into a polar orbit.
Cost of the SURFSat project from beginning to end was $3 million.
The primary SURFSat-1 experiment was supported by the Deep Space Network Advanced Systems Program, sponsored by the NASA Office of Space Communications. Support for the second experiment was provided by the U.S. Space Very Long Baseline Interferometry Project at JPL, sponsored by NASA's Astrophysics Division. Support for the integration of the satellite with the Delta II launch vehicle was provided by personnel of the Orbital Launch Service Office at the NASA Goddard Space Flight Center, Greenbelt, MD, and McDonnell Douglas Aerospace.
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