(1a) DEFENSE AGAINST ASTEROIDS BEGINS STUDY By Robert Roy Britt SPACE.com July 13, 2004 A mission to smash into a space rock to deflect it and study its structure has been given priority over five other potential asteroid projects by the European Space Agency. The slam-bang 'Don Quijote' mission would help scientists figure out how to deflect or destroy any asteroid in the future that might be found to be on a collision course with Earth. The project uses the Spanish spelling of Don Quixote, the protagonist in Cervantes' novel who has chivalrous ideas that tend toward the impractical. The lofty modern-day Don Quijote would help solve a practical problem. Scientists don't know enough about asteroid insides to predict how one would respond to attempts to nudge it off an Earth-impact course or turn it into harmless dust. While no asteroids are currently known to be on track to hit the planet, experts say a regional catastrophe is inevitable in the very long run-- over millennia. And run-ins with small asteroids that could incinerate a large city occur ever few thousand years. "We want to investigate the internal structure of an asteroid, and at the same time develop and test the technology necessary, in a worst case scenario, to deflect a sizeable asteroid," says Andrea Milani, an asteroid expert at the University of Pisa who is helping to plan the mission. The mission would involve two spacecraft -- Sancho and Hidalgo launched on different trajectories toward one asteroid about 500 meters in diameter. A rock that size would cause serious damage across a widespread area and absolute destruction at the local level. Sancho would arrive first and orbit the asteroid for several months. It would deploy some penetrating probes to form a seismic network on the asteroid to examine its structure before and after its sister craft's smashing arrival. Hidalgo would crash into the asteroid at about 10 kilometers per second. Sancho would observe from a safe distance, then move in for a closer look. It would study changes in the asteroid's orbit, rotation and structure caused by the impact, said Willy Benz, a member of the mission's study team from the University of Bern in Switzerland. The mission would "provide information about how an asteroid reacts to such stresses, which is an important step in the whole impact hazard reduction business," Benz said. A European Space Agency panel considering six asteroid protection missions recommended Don Quijote "as the highest priority for further studies," Benz said. It is still in an early planning stage, however, and would eventually need funding approval. He said the mission could launch in five to six years. Don Quijote is similar to NASA's Deep Impact mission, which is slated to fling a small probe at a comet on July 4, 2005. Comets are loaded with water ice, while asteroids are generally composed of rock and metals. Scientists know little about either, and both are thought to harbor clues about the solar system's formation. From a safe distance, the Deep Impact mothership will take pictures and record other data as its probe blows a seven-story-deep crater in the comet Tempel 1. Experts say Deep Impact's cosmic fireworks might be visible from Earth to backyard skywatchers. Both missions will alter the courses of the objects they hit. Deep Impact will fly past its target, limiting the time for close-up observations. The European craft, in orbit around its as-yet-unknown target, would take a more detailed approach to studying the comet before, during and after the collision. "The important difference between Deep Impact and Don Quijote is that the target asteroid is studied six to seven months prior to impact and again three to four months after the impact," Benz said. Don Quijote could create a seismic shift in the understanding of asteroid interiors. The probes that would be embedded in the asteroid prior to the main event would monitor how the rock's structure changes in the collision by recording seismic waves created by small explosions the probes detonate. The method was used by Apollo astronauts to examine the Moon's interior, and it's used on Earth to search for oil, natural gas and other minerals. There are currently no firm plans by NASA or any other agency to deal with any impending asteroid catastrophes. Scientists have contemplated the theory of asteroid deflection and destruction, but no tests have been performed like the one planned in the Don Quijote mission. "Although the probability of a big impact is very small, for the first time in human history we have the means of avoiding such a catastrophic event," Jose Gonzalez, another member of the study team, has said. "But it is essential that we improve our knowledge of asteroids. We must know in detail the internal structure of asteroids, and how they respond to impacts before we can design effective mitigation methods." (1b) ESA MISSION TO MOVE AN ASTEROID Space Daily, 15 July 2004 On 9 July 2004, the Near-Earth Object Mission Advisory Panel recommended that ESA place a high priority on developing a mission to actually move an asteroid. The conclusion was based on the panel's consideration of six near-Earth object mission studies submitted to the Agency in February 2003. Of the six studies, three were space-based observatories for detecting NEOs and three were rendezvous missions. All addressed the growing realisation of the threat posed by Near-Earth Objects (NEOs) and proposed ways of detecting NEOs or discovering more about them from a close distance. A panel of six experts, known as the Near-Earth Object Mission Advisory Panel (NEOMAP) assessed the proposals. Alan Harris, German Aerospace Centre (DLR), Berlin, and Chairman of NEOMAP, says, "The task has been very difficult because the goalposts have changed. When the studies were commissioned, the discovery business was in no way as advanced as it is now. Today, a number of organisations are building large telescopes on Earth that promise to find a very large percentage of the NEO population at even smaller sizes than visible today." As a result, the panel decided that ESA should leave detection to ground-based telescopes for the time being, until the share of the remaining population not visible from the ground becomes better known. The need for a space-based observatory will then be re-assessed. The panel placed its highest priority on rendezvous missions, and in particular, the Don Quijote mission concept. "If you think about the chain of events between detecting a hazardous object and doing something about it, there is one area in which we have no experience at all and that is in directly interacting with an asteroid, trying to alter its orbit," explains Harris. The Don Quijote mission concept will do this by using two spacecraft, Sancho and Hidalgo. Both are launched at the same time but Sancho takes a faster route. When it arrives at the target asteroid it will begin a seven-month campaign of observation and physical characterisation during which it will land penetrators and seismometers on the asteroid's surface to understand its internal structure. Sancho will then watch as Hidalgo arrives and smashes into the asteroid at very high speed. This will provide information about the behaviour of the internal structure of the asteroid during an impact event as well as excavating some of the interior for Sancho to observe. After the impact, Sancho and telescopes from Earth will monitor the asteroid to see how its orbit and rotation have been affected. Harris says, "When we do actually find a hazardous asteroid, you could imagine a Don Quijote-type mission as a precursor to a mitigation mission. It will tell us how the target responds to an impact and will help us to develop a much more effective mitigation mission." On 9 July, the findings were presented to the scientific and industrial community. Representatives of other national space agencies were also invited in the hope that they will be interested in developing a joint mission, based around this concept. Andrés Galvez, ESA's Advanced Concepts Team and technical officer for the NEOMAP report says, "This report gives us a solid foundation to define programmatic priorities and an implementation strategy, in which I also hope we are joined by international partners". With international cooperation, a mission could be launched as early as 2010-2015. ------------------------------------------------------- (2) TOUTATIS: CLOSE FLYBY SEPTEMBER 29, BUT NO THREAT A user of this website recently wrote I was on Nasa NEO Impact Website and went into the (Impact risks) section and did not find Toutatis, Why is this Asteroid not listed? Is this Asteroid under investigation? Reply: Toutatis, with a length of more than 5 km, is one of the largest near-Earth asteroids. On September 29 it will make an unusually close approach, about 1.5 million km from Earth, but there is no danger of collision. One of the advantages of coming so close is that astronomers can use radar to make images of this asteroid, and they will certainly be doing so in late September. You can see radar images from the 1996 close pass of Toutatis at <http://neo.jpl.nasa.gov/images/toutatis.html>. You should not be concerned about this close flyby. Because it is so large and well observed, the orbit of Toutatis is known with great precision. and it does not threaten Earth in any way. That is why it is not listed on NASA websites as an impact risk. Millions of years from now, however, it could hit our planet. If and when that happens, a Toutatis impact would be large enough to cause the extinction of many species. But that is a long time in the future. For more information, you could read Robert Britt's article of May 3 at <http://www.space.com/scienceastronomy/mystery_monday_040503.html>. Another good source of information is Alain Maury's Toutatis webpage at <http://www.astrosurf.com/maury/asteroides/toutatis.html>. (3) SAGAN MEDAL RECOGNIZES PUBLIC OUTREACH ON THE NEO IMPACT THREAT AMES ASTEROID HUNTER WINS SAGAN AWARD By David Perlman San Francisco Chronicle David Morrison, an astronomer, author, lecturer and senior scientist at NASAs Astrobiology Institute at Ames Research Center in Mountain View, has been awarded this years Sagan Medal by the American Astronomical Societys Division for Planetary Sciences. Morrison is best known for analyzing the flight paths of so-called near-Earth asteroids and comets that although rare might one day wreak havoc if any should actually crash into the Earth. The NASA astronomer has led teams of scientists considering ways to nudge or blast such objects out of the way if calculations show any are in fact on a direct collision course with our home planet. In Earths history, Morrison has reminded people during his frequent public lectures, one such object, known as the Tunguska meteorite, exploded so violently less than 4 miles above a river in Siberia that more than 1 million trees were leveled over an area of nearly 1000 square miles and instruments recorded the blast more than 600 miles away. An even larger event was the famed asteroid crash of 65 million years ago that caused the extinction of all of Earths dinosaurs as well as countless other living species. The asteroid crash created the huge Chixulub crater in the Caribbean off Mexicos Yucatan peninsula.... The Sagan medal is the highest honor [for public outreach] awarded by the Division for Planetary Sciences. It is named for the late Cornell space scientist Carl Sagan, who was Morrisons professor when Sagan was on the Harvard faculty. |
