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Faint artificial signals heard from Mars - did the MPL make it after all?Signature detected in data from weeks ago / Could also be interference / Mission rescue very unlikelyJPL has decided to send another set of commands to Mars to investigate the possibility that a signal detected by a radio dish at California's Stanford University came from Mars Polar Lander. Mission managers had sent commands several times in December and January instructing MPL to send a radio signal to the 45-meter antenna at Stanford. Although no signal was detected in real-time, the team in charge of the Stanford antenna says that after additional processing of the data they may have detected a signal that could have come from Mars during tests on December 18 and January 4.Because the signal was so weak, it took several weeks for the Stanford team to process their data and reach this conclusion. The signal is definitely artificial, but there are any one of a number of places it could have originated on or near Earth: It could be a backup radio on the lander trying to relay a message through the MGS or a stray television broadcast from Earth. But it is considered intriguing enough to renew the efforts to talk to the MPL which had been abandoned on Jan. 17th (see Update # 168 last story). So new commands were sent at 18:00 UTC on Jan. 25th. They instructed the lander, if it is operating, to send a signal directly to Earth to the Stanford antenna the following day. The Stanford receiving station was to listen again during the window on the 26th to see if it could pick up a signal that could originate from Mars. The results of this test will not be immediate and it will take the team several days to process the data. Although the Stanford data from the previous tests took several weeks to process, the team expects to have results within several days now that they know what they are looking for. Even if the signal were coming from the lander, there is little hope that any science could be returned. However, it would give the team a few more clues in trying to eliminate possible failure modes: If the signal is repeated the best one can hope for is "a handful of bits" that might hold clues as to just why the lander malfunctioned. |
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Charity concert to promote German astrometry satelliteThe dire financial situation of Germany's national program for space science has led to an unusual event: On May 6th a charity concert will take place in Mannheim that could raise over DEM 100 000 - money that will go to the astronomical institutes that want to build the Double Interferometer for Visual Astrometry or DIVA satellite, a successor for ESA's highly successful HIPPARCOS satellite and a competitor with NASA's recently selected FAME satellite (see Update # 152 story 11). Of course the money to be raised would cover no more than 1/1000 of the overall mission cost - but it could trigger the government's approval of the project.The concert (a special version of Mozart's "Magic Flute") is just one activity by the Klaus Tschira Foundation to promote the mission: In parallel donations will be collected - and the donors then be honored by having their names inscribed in a big metal monument to be erected in Mannheim. There have never been attempts for this kind of fundraising for a space science mission in Germany, so there's no telling how successful it will be and if it might convince the government eventually to come up with the balance. But even if not, the money raised would go to two astronomical institutes in Heidelberg. |
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Minotaur launches package of small satellitesA modified Minuteman ICBM successfully launched a payload of small satellites at 3:03 UTC on Jan. 27th. The "Minotaur" is a modified Minuteman ICBM that uses the first two stages of decommissioned Minuteman 2 ICBMs and the upper two stages of the commercial Pegasus XL booster. Together they can place up to 340 kg into a 740-km Sun-synchronous orbit, about 50 percent more than the Pegasus XL alone. At its maiden launch the Minotaur carried several microsatellites within a payload adapter called JAWSAT as well as two other payloads that will remain attached to it after launch.U.S. Air Force officials at first were cautiously optimistic the $23 million test flight of the new OSP Minotaur rocket was successful: A lack of data from the booster had left some questions unanswered, including the exact orbit achieved and proper execution of the payload deployment sequence. What space authorities can confirm is the fact five objects are orbiting the Earth from this launch. However, there should be six including five satellites and the rocket's spent upper stage. Later it was stated that "all indications that we have said everything has been delivered to the correct orbit." |
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Why the Spanish 'ice bombs' are not from outer spaceLast week the Chemistry Department of the University of Valencia obtained a detailed analysis of one reliable ice ball fallen near Valencia. From this and other analysis obtained by the Spanish Higher Council for Scientific Research (CSIC) we can say that the objects really fallen from the sky are composed of water ice with little quantities of some common salts. In all cases the isotopic composition corresponds closely to the natural isotopic mix of atmospheric water. In these conditions, we must remark here that none of solar system objects (comets either) have similar composition.We know that cometary ice is a very complex mixture of dust particles with ices of water, methane, ammonia, etc... In any case all cometary components have important isotopic anomalies: All this leads to conclude that the reported falls of ice objects in Spain and, recently, in Italy are originated by an atmospheric unknown phenomenon or, more probably as in other occasions, due to natural ice formation on the fuselage or ejection of on-board water in aeroplanes. In any case a cosmic origin is highly improbable. (Adapted from Josep Ma. Trigo i Rodriguez in IMO News of Jan. 26) I feel I ought to make some brief comments about this item from the point of view of being someone involved in the official investigation. Although it is true that an extraterrestrial origin was one of the hypotheses suggested for the Spanish ice balls (of which, out of more than 60 reported falls, only some 5 or 6 are currently regarded as being genuine), this is only because no reasonable theory was discounted initially. However, this was never one of the more favoured ideas. In fact, the evidence against an extraterrestrial origin is very strong:
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A new component of the Milky Way?Is there a "protodisk" consisting of White Dwarf stars in between the disk of the Galaxy and its extended dark matter halo? Such a scenario has been proposed as an explanation for the detection of "MACHO"s (Massive Astrophysical Compact Halo Objects) by several groups in recent years. Some models explain these rather frequent microlensing events with White Dwarfs in the halo, but that raises more questions than it would answer - e.g. where would all the heavy chemical elements be that the dying stars, the precursors of the WD stars, would have pumped into the interstellar medium?The new component of the Milky Way now proposed, the "white dwarf protodisk", is a highly flattened sphere, about 150 000 light years long and 90 000 light years high, which surrounds the disk. At least 10 billion years old, the white dwarf protodisk would be much older than the disk and constitute the fossil remains of the earliest stars in the Galaxy. A WD Protodisk could explain both the MACHO detections and the proper motion studies in the Hubble Deep Field where distant faint stars seem to move (see Update # 148 story 4 sidebar). Such a component would have far fewer white dwarfs than a halo model and so there will be far less pollution of the galaxy with the heavy elements produced when the original star runs out of fuel and becomes a white dwarf. It also provides a more natural distribution for the remains of an early starburst population, which might be expected to be in a more condensed component than the halo. This component, though, could account for less than 5% of the dark matter that represents most of the mass of the Galaxy: One still needs something more exotic components such as Cold Dark Matter to explain most of the missing mass in the Galaxy and in the Universe. |
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Off-center spiral galaxies may provide clue to Dark MatterNew computer simulations support the belief that "lopsided" spiral galaxies are sloshing about in halos of dark matter. Such galaxies have spiral arms and interstellar gas and dust that are not distributed uniformly around the bright center, or nuclear bulge, of the galaxy - a third of all spiral galaxies may have these lopsided structures, including M 31 in Andromeda, M 33 in Triangulum and M 101. The new simulations give strong evidence that when the visible stars, gas, and dust in the disk respond to a passing galaxy more readily than does the dark matter, the spiral galaxy's visible matter is pulled off-center, creating lopsided galaxies. Dark matter that is relatively hot moves rapidly and therefore responds relatively little to the gravitational tug of a passing galaxy.Since stars and cool gas in a galaxy respond more strongly than the halo, these latter elements are pulled slightly away from the halo as the other galaxy passes. Simulations reveal that as the galaxies move away from each other, stars and cool gas swirl back to the halo's center. Had the dark matter all been of the proposed cool variety (such as the MACHOs discussed in the previous story, then the halo would be shifted by the other galaxy's gravity as much as the visible stars and gas. In that case, the observed sloshing of stars and gas does not occur. The results of the simulations suggest that at least some of the dark halo matter in disk galaxies is of the proposed hot, rapidly moving variety. |
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"Dying quasars" in nearby galaxiesThe mechanism that powers distant quasars is also at work in the cores of many nearby galaxies, only at a much lower activity level: The same compact 'flat spectrum' radio sources previously seen in quasars are abundant in the centers of otherwise normal galaxies, a survey with the Very Large Array showed. The stronger radio nuclei of these galaxies were then observed at 6 cm wavelength with the Very Long Baseline Array, which provides much finer resolution than the VLA. The size of the radio source in the nuclei of all the galaxies observed was found to be tiny (a fraction of a light year), but very bright, like quasars - and completely unlike the radio emission of galaxies with gas ionized by radiation from stars, as an alternative interpretation had been. So these galaxies apparently contain the same kind of 'central engine' (widely believed to be a supermassive black hole), slowly accreting gas from the surrounding galaxy. This process is the same as that believed to power quasars, but at only a fraction of the accretion rate. |
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The first HST pictures after the repair missionwere taken January 10-13, 2000, and have now been released - one object is an intricate structure of shells and streamers of gas around a dying sun-like star 5000 ly away, the other a massive cluster of galaxies called Abell 2218, which acts as a gravitational lens: STScI, ESA and NASA Press Releases, coverage by CNN, BBC, WELT, SpaceRef and SPIEGEL, the pictures of the Eskimo Nebula and Abell 2218.What was it like to repair Hubble? The recent mission STS-103 in the words of the astronauts themselves at a recent press briefing. Stardust's orbital maneuver completeThe comet probe finished a most important and complex maneuver on Jan. 22, positioning it for a swing around the Earth next year and a close encounter with comet Wild 2 in 2004: Space.com, Discovery, Mission Status.T - 3 years for Rosetta and counting - deadline for Europe's next comet launch looms: ESA Science News. NEAR completes rendezvous rehearsal, with the spacecraft performing flawlessly: News Flash, Space Daily version. H2 engine raised from the oceanOn Jan. 22 the Japanese space agency has succeeded in raising the first-stage engine of the H-II Launch Vehicle No.8 (lost last November) from the sea about 380 km northwest of the Ogasawara Islands: Press Release with a picture, coverage by SpaceViews, Space.com.1 AU worth 1 million bucks...The distance from the Earth to the Sun was the last of 15 things a contestant in the popular ABC show "Who wants to be a Millionaire" had to know last week - and the right Astronomical Unit ("93 million miles") won him the grand prize that had eluded all but one candidate before. Yeah, right, but would he have known the answer in real units, like kilometers...? (CNN [Showbiz Today] of Jan. 20) |
Terra suffers thruster problemA thruster problem earlier this month kept controllers from placing the Terra Earth-observing spacecraft into its final orbit - all other systems on the spacecraft are performing "extremely well": Spaceflight Now, SpaceViews, Space Daily.Astronomy from military aircraft?U.S. astronomers have just completed a successful proof-of-concept program that takes astronomy and astronomers into the backseat of high performance, two seater military jet aircraft used by NASA for flight testing. The test program culminated on January 9th with the successful observation from a NASA F-18 of an asteroid occulting a star using the SWUIS-A airborne astronomical imager (that has also flown on the shuttle): SWRI special page, BBC story.The airborne astronomers also want to hunt for "Vulcanoids", possible asteroids inside the orbit of Mercury: Space.com. More pictures, stories of the lunar eclipseon Jan. 20/21: C. Bassa, M. Verstraaten, A. McCubbin, A. Danielsen, R. Snow, J. Rummel, D. Pugh, M. Holl and the BBC again (new pictures). More results: Fla. Today (scroll down to Jan. 21), RP and Yahoo.
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