SB NEWS @ AMSAT $SPC0331 * SpaceNews 31-Mar-97 * BID: $SPC0331 ========= SpaceNews ========= MONDAY MARCH 31, 1997 SpaceNews originates at KD2BD in Wall Township, New Jersey, USA. It is published every week and is made available for non-commercial use. * PHASE III-D LAUNCH DELAY * ============================ In a formal announcement from Paris on March 24th, the European Space Agency ( ESA ) said that the second test flight of their new Ariane 5 booster has now been re-scheduled from July to mid-September, 1997. It is this flight, Ariane 502, on which Phase 3-D is currently manifested. According to their latest announcement, this action was being taken by ESA and CNES (the French Space Agency which manages the Ariane 5 program for ESA) in order to "improve (the booster's) robustness, increase the operational margins and allow for degraded operating modes". In a joint statement a day after the ESA announcement, Phase 3-D Project Leader and AMSAT-DL President, Dr. Karl Meinzer, DJ4ZC, along with AMSAT-NA President Bill Tynan, W3XO, expressed continuing confidence that ESA and CNES will succeed in completing all the tasks necessary for a successful flight test of Ariane 502. "Naturally, we are disappointed that our launch will not be as soon as we had hoped", said Meinzer. "However, I am pleased that ESA and CNES are taking care to improve the operational margins for the Ariane 5 booster. This action helps give us renewed confidence in the overall probability for a successful launch of our satellite," he said. Both Meinzer and Tynan emphasized, however, that this launch delay, like the earlier ones, means that the total cost of the Phase 3-D Project will increase significantly. Even before the latest ESA announcement, AMSAT-DL and AMSAT-NA were projecting a combined budget shortfall of about two hundred thousand dollars (US) in the money needed to complete their respective tasks on the project. "This shortfall can only increase now as a result of this latest schedule change", said Tynan. Both AMSAT leaders urged everyone to continue doing as much as they possibly can to insure the needed funds will be in place for the completion and launch of Phase 3-D. [Info via the AMSAT News Service] * HALE-BOPP NEWS * ================== Completing an unprecedented year-long study of Comet Hale-Bopp using two NASA observatories, the Hubble Space Telescope and the International Ultraviolet Explorer, astronomers report that they are surprised to find that the differences in the nucleus seem to be isolated from each other. They also report seeing unexpectedly brief and intense bursts of activity from the nucleus during the monitoring period. The Hubble observations suggest that the nucleus is huge, 19 to 25 miles (30 to 40 kilometers) across. The findings, by a team of scientists, led by Johns Hopkins astrophysicist Harold Weaver, are being published in the March 28 issue of the journal Science. "Hale-Bopp will probably provide the most revealing portrait of the workings of a cometary nucleus since the spacecraft missions to comet Halley in 1986," said Weaver. "This is a unique opportunity; we have never had the chance to examine a comet in this much detail, over this large a range of distance from the Sun." The key results: Violent Eruptions on the Comet's Surface During the course of long-term observations, which began in August 1995, astronomers unexpectedly caught the comet going through a sudden brief outburst, where, in little more than an hour, the amount of dust being spewed from the nucleus increased at least eight-fold. "The surface of Hale-Bopp's nucleus must be an incredibly dynamic place, with `vents' being turned on and off as new patches of icy material are rotated into sunlight for the first time," Weaver said. A Complex, Mottled Nucleus To their surprise, astronomers found that water ice sublimates (turns directly from a frozen solid into a gas) at a different rate than the trace ices, implying that those components are not contained within the water on the comet. This conclusion is further supported by Hubble data showing that the rate at which dust left the nucleus was much different than the sublimation rate of water. This result is contrary to previous models for a comet's nucleus which suggest that the trace components, such as carbon disulfide ice, are contained inside of the most abundant ice on the comet, frozen water. As water sublimates the trace components and dust should be released at similar rates, but this is not what Hubble observed. A Monstrous Nucleus By studying Hubble Space Telescope images, the astronomers have estimated that its nucleus may be about 19 to 25 miles (30 to 40 kilometers) in diameter. The average comet is thought to have a nucleus of about 3 miles (5 kilometers) in diameter, or even smaller. The comet or asteroid that struck the Earth 65 million years ago, possibly causing the extinction of the dinosaurs, was probably about 6 to 9 miles (10 to 15 kilometers) across. Because Hale-Bopp was unusually bright when it was still a great distance away, well outside the orbit of Jupiter, it has given scientists their best view ever of the changes in a comet's nucleus as it gets closer to, and is progressively heated by, the sun. Those changes, in turn, provide information about the composition and structure of comets, which are believed to be remnants from the formation of the solar system, about 4.6 billion years ago. Learning more about comets can provide important information about the materials and processes that formed the solar system. Image files in GIF and JPEG format and captions may be accessed on Internet via anonymous ftp from ftp.stsci.edu in /pubinfo. GIF JPEG PRC97-08 Hale-Bopp gif/hb9596.gif jpeg/hb9596.jpg Higher resolution digital versions (300 dpi JPEG) of the release photograph are available in /pubinfo/hrtemp: 97-08.jpg (color) and 97-08bw.jpg (black & white). GIF and JPEG images, captions and press release text are available via the World Wide Web at http://oposite.stsci.edu/pubinfo/PR/97/08.html and via links in http://oposite.stsci.edu/pubinfo/Latest.html or http://oposite.stsci.edu/pubinfo/Pictures.html. [Info from The Space Telescope Science Institute via Larry Van Horn] * FEEDBACK/INPUT WELCOMED * =========================== Comments and input for SpaceNews should be directed to the editor (John, KD2BD) via any of the paths listed below: WWW : http://www.njin.net/~magliaco/ PACKET : KD2BD @ KS4HR.NJ.USA.NA INTERNET : kd2bd@amsat.org, magliaco@email.njin.net SATELLITE : AMSAT-OSCAR-16, LUSAT-OSCAR-19 <<=- SpaceNews: The first amateur newsletter read in space! -=>> /EX