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By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| An experimental German companion. Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
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Two exoplanets smaller than Saturn foundTwo extrasolar planets with masses even below Saturn's (which equals 95 Earths) have been found with the trusted radial-velocity method: This feat, thanks to a spectrograph at the Keck telescopes, is being hailed as yet another major milestone in the quest to eventually find and study 'other Earths' in the Universe. Of the 30 planets around sun-like stars detected previously outside our solar system, all had been the size of Jupiter or larger: Finding Saturn-sized planets reinforces the theory that planets form by a snowball effect of growth from small ones to large, in a star-encircling dust disk. This 20-year-old theory predicts there should be more small planets than large planets, and this is a trend the researchers are beginning to see.Jupiter alone is three times the mass of Saturn (and 318 times the mass of Earth): This had left the nagging possibility open that some of the extrasolar planets might really be brown dwarfs, which would form like stars through the collapse of a gas cloud - but now researchers are better assured these "Jupiters" are only the tip of the iceberg, and there are many more planets to be found that are the mass of Saturn or smaller. Before the first exoplanets had been found 5 years ago, most theorists had expected all 'solar systems' to resemble ours, then all bets about the 'typical' exoplanets were off, but now it seems that Sol and its planets are not that unusual after all. The new discovery was made by the well-known planet-sleuths Geoff Marcy, Paul Butler and Steve Vogt with the Keck telescope in Mauna Kea, Hawaii. They found a planet with at least 80 percent the mass of Saturn (or 0.25 Jupiter or 80 Earth masses) orbiting a constant 6.1 million km from the star HD46375, 109 light-years away in Monoceros, and a planet 70 percent the mass of Saturn (or 0.22 Jupiter or 70 Earth masses) with an elliptical orbit (e=0.3) at a mean distance of 52.3 million km around the star 79 Ceti alias HD16141, located 117 light-years away in Cetus. Both these planets are very close to their stars and so have short orbits: They go around their parent stars with periods of 3.02 days and 75 days respectively. This allowed for their relatively rapid discovery. |
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MPL disaster report calls premature engine shutdown, crash "probable" cause of lossSilence of Deep Space 2 probes remains a mysteryAs expected the investigators looking into the loss of the Mars Polar Lander could not reach absolute certainty in their conclusions - but they present a very likely scenario: An erroneous shutdown of the lander's descent engines (as first mentioned in Update # 176) probably led to a crash landing. "The probable cause of the loss of MPL has been traced to premature shutdown of the descent engines, resulting from a vulnerability of the software to transient signals," the 154-page Casani report says in its Executive Summary: "Owing to the lack of data, other potential failure modes cannot positively be ruled out. Nonetheless, the Board judges there to be little doubt about the probable cause of loss of the mission." When the engines went out, the MPL was still 40 meters above the ground which it then hit with 22 meters per second instead of 2.4 m/s - that would not have been survivable."In contrast, the Board has been unable to identify a probable cause of the loss of DS2," the same report says: "The loss of both probes can be accounted for by a number of possibilities," with 4 scenarios the most plausible. In any case there was a basic problem with Deep Space 2 - the mission was simply not 'ready to fly': "As originally approved, the development plan included a system-level qualification test that was ultimately deleted," the Casani report says. "This represented an acknowledged risk to the program that was assessed and approved by JPL and NASA management on the basis of cost and schedule considerations" - a fatal mistake. Here is how the MPL most likely died, as summarized on p. 26 of the Casani report: "A magnetic sensor is provided in each of the three landing legs to sense touchdown when the lander contacts the surface, initiating the shutdown of the descent engines. Data from [...] tests [on models as well as during the preparations of the (former) 2001 lander] showed that a spurious touchdown indication occurs in the Hall Effect touchdown sensor during landing leg deployment (while the lander is connected to the parachute). The software logic accepts this transient signal as a valid touchdown event if it persists for two consecutive readings of the sensor. The tests showed that most of the transient signals at leg deployment are indeed long enough to be accepted as valid events, therefore, it is almost a certainty that at least one of the three would have generated a spurious touchdown indication that the software accepted as valid. The software - intended to ignore indications prior to the enabling of the touchdown sensing logic - was not properly implemented, and the spurious touchdown indication was retained. The touchdown sensing logic is enabled at 40 meters altitude, and the software would have issued a descent engine thrust termination at this time in response to a (spurious) touchdown indication." More general conclusions by the MPL investigators as well as a different panel (chaired by Thomas Young) on the whole NASA Mars program:
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Finding life on Mars could cause the end of explorationThe issue of life on Mars is a double-edged sword, where scientific passion and ethics cuts both ways: On one hand, the mystery of whether that - perhaps - once warmer and wetter place in space supported life has served as a magnet to tug on public and scientific exploration interests. On the other, should the prospect that the Red Planet is at present a thriving "Marsopolis" for Martian microbes cause a pause in planting human life there? |
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IMAGE launched: Making 'pictures' of the magnetosphereThe magnetosphere of the Earth has been a topic of intense investigation since the very first satellites were launched in the 1950's - but all missions so far have just put spacecraft somewhere inside this giant structure of fields and particles surrounding the Earth: To get from these isolated in-situ data to a complete picture of the magnetosphere has always involved a lot of modelling. NASA's latest magnetospheric spacecraft IMAGE, the Imager for Magnetopause-to-Aurora Global Exploration, will go a step further: This first representative of the MIDEX series of moderately priced science satellites, launched on March 25th, will use its 6 instruments to 'image' the whole magnetosphere, using three different techniques. And all the data will be available to the world immediately, without any proprietary time for the IMAGE researchers.The methods used by IMAGE from its polar orbit to get a 3D "image" of the densities, energies and masses of charged particles throughout the inner magnetosphere are
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Uncontrolled reentry planned for Iridium satellitesThe deliberate destruction of the Iridium satellite constellation (see Update # 182) will not be a tightly controlled affair such as the downing of the CGRO (see last Update): Apparently Motorola will command the satellites from their current 780 km level just a bit down into the upper atmosphere and then let it do the rest - without a specific date for the burn-up. This will be tried out first with some of the spare satellites, then the others are to be brought down in groups. (AW&ST of March 27, p. 39-40)"Save Our Satellites!" demands yet another website of people who want to buy(!) the satellite constellation - they are also mentioned in Salon. More voices are heard here. The call for astronomical observations of the burning satellites (see Update # 182 story 1 sidebar) is now being echoed on more and more websites: CCNet (item 4) and Space.com = EZ - the uncontrolled nature of the reentries may make these plans complicated, though. A spectacular Subaru picture of M 82has been published, showing the red ionized hydrogen gas filaments extending perpendicular to the galaxy in fine detail - the outflow is being driven by the copious formation of massive stars, a starburst, and subsequent supernova explosions: Press Release. One Subaru instrument after the other is now seeing "First Light": Latest News and all PR pictures. Coverage by BBC, Discovery, SPIEGEL, Spaceflight Now.Quake shows that 'anomalous pulsars' are neutron stars, tooOne of the few known Anomalous X-ray Pulsars has experienced an "earth" quake - a sudden, catastrophic shifting of the star's interior - that is similar to quakes seen in regular neutron stars. This provides strong confirmation that the AXP is indeed a neutron star and has properties surprisingly similar to its "non-anomalous" cousins: GSFC Press Release, Space.com, SpaceViews.Life-on-a-neutron-star novel gets 20 - an interview with Robert Forward on his imaginative "Dragon's Egg": Space.com, details, Forward. Are U.S. space launches too safe?It's rare enough that some aspect of the American space program is being called too good by a panel of outside experts - but apparently there is too much effort going into range safety precautions, and a lot of money could be saved by "Streamlining Space Launch Range Safety," as the NRC report is called: NRC Press Release (Space Daily, Spaceflight Now versions), Space.com, SpaceViews. |
"Warranty" for the ISS running outThe 496-day guarantee for Russian-built electronic equipment runs out on March 30th, but NASA expects the space station to keep running normally until astronauts arrive in mid- to late April with new batteries, fans, air filters, fire extinguishers and smoke detectors: AP ( Discover, Space.com versions).STS-101 astronauts still upbeat despite equipment, training woes: CNN. Atlantis rolls out: SpaceViews. Earliest launch date now April 18: Discovery, Fla. Today. The latest ISS assembly schedule revision: Status Report. New reports raise concerns about the ISS - two key Russian-built modules, the Zarya control module already in orbit and the Zvezda service module to be launched in July, fail to meet some important safety requirements, and the science utilization of the station isn't guaranteed either: SpaceViews. First privately financed Mir launch set for April 4"The April 6 docking will fulfill MirCorp's promise to reactivate Mir preparing it for commercial operations that are expected to range from industrial production and scientific experimentation to space tourism and in-orbit advertising": MirCorp Homepage and Press Release.Cosmonauts fly to launch pad for the 28th mission to the station: Space.com, AFP, Reuters. Linenger tells what it was like during his 5 months on Mir - especially the Feb. 1997 fire: Space.com. Trouble during simulated stay on space station - fights have broken out between trainee cosmonauts during an experiment in Russia to see how future space pioneers would cope with long and lonely stretches in space : BBC.
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Compiled and written by Daniel Fischer
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