Asteroid Early Warning System: German Satellite to Help Detect Threats to Earth
With a new satellite project, Germany's space agency is hoping to create an early warning system for potential asteroid strikes against the Earth. An asteroid impact may have contributed to the death of the dinosaurs, and scientists would like to be able to predict the next Earth-bound collosus before it hits.
The atmosphere is reminiscent of the bridge on the Starship Enterprise. A dozen workspaces are arranged in a semicircle, each blue-seated place is equipped with a large square monitor, a Webcam, headphone and microphone. A central console is located in the middle of the room, within view of the camera embedded in the wall. This is where Captain Kirk would most likely sit and issue his commands.
But because we are located on the outskirts of Bremen, just a stone's throw from the highway, and not somewhere in the vastness of the universe, Captain Kirk and Jean-Luc Picard are nowhere to be found. In their place sit engineers and scientists. Here, on the bright ground floor of the Bremen branch of the German Aerospace Center (DLR), the country's space agency, they are building satellites. The "Concurrent Engineering Facility" is what researchers call this futuristic workspace -- and the work they are doing here could possibly save the Earth.
Researcher Marcus Hallmann points to one of the three impressively large monitors at the front of the central planning office. It looks like colorful confetti is dancing around his fingers. Red, green, yellow and white dots move back and forth, in constant motion. Surrounded by the hubbub, there are two labeled ellipses -- the orbits of the Earth (green) and Venus (pink), Hallmann explains. And each of the colorful, moving points could, in theory, inflict great harm on Earth.
Scientists Don't Have Enough Information on Asteroids
The display shows all the celestial objects orbiting inside our solar system. But they could become celestial missiles that endanger the Earth if, for instance, they were to be influenced by Venus' gravitational field and enter a different path -- a more dangerous one that could see them hurtling toward Earth. In the short term, though, the danger of an asteroid crashing into Earth is mostly hypothetical, according to scientists working in the field. As far as they can tell, there is no clear and present danger.
Still, one of the main problems with research into this area is that the information scientists currently have is only sufficient for making the most rudimentary of predictions. Additionally, the advance warning time is far too short.
"All of these asteroids present a potential danger to the Earth," Hallmann says. Simply by looking at standard distribution statistics, researchers suspect that there are around a thousand objects like this traveling in orbits between Earth and the sun, each of them at least 100 meters in size. Yet they only have actual knowledge of ten of these sorts of rocks in space. "We know next to nothing about asteroids between Earth and the sun," says Ekkehard Kührt, head of the Asteroids and Comets division of DLR's Institute of Planetary Research in Berlin. The brightly colored computer simulation belies the scientist's depth of the knowledge about the asteroids -- in reality they do not know this much, at least not yet.
AsteroidFinder to the Rescue
And that's where a satellite currently being developed in Germany can play a role. Plans for the satellite -- which according to its builder, will be 80 centimeters wide and deep and 100 centimeters high, as big as a small refrigerator -- are slowly taking shape in Bremen. The plan is to have the satellite operational by 2013.
Prior to this initiative, it was primarily the Americans who were interested in the search for asteroids. But researchers often lacked sufficient funding. In addition, the Americans have primarly conducted research into the astroid belt between Mars and Jupiter. By contrast, the German satellite will observe what are known as "inner Earth objects," which are traveling closer to Eath. "Up until now there have been no efforts to try to find this type of asteroid," Kührt explains.
There are a lot of problems to solve, not the least of which is fairly mundane-sounding issue: If you stare into the sun during the day, you will have little serious chance of seeing any stars. So how can one hope to be able to recognize a few comparably small, faint stones?
To some degree the AsteroidFinder has good potential to overcome this issue: Its planned orbit takes it around the earth along the border of day and night, also known as the Terminator line or the twilight zone. No matter what, the 25 centimeter telescope will still need to be able to make highly precise scans. In theory the satellite will be carrying a computer chip, similar to the kind that is used in commercial digital cameras. But the chip must be cooled down to temperatures as low as -80 Celsius and be exceptionally good at filtering out any static.
Fast shutter speeds should help ensure that the pictures are not as out of focus as some jittery holiday snapshot of a walk on the beach at dawn. Numerous snapshots from the satellite will be used to compose the celestial images. Each day, AsteroidFinder is expected to send around 14 gigabytes of data back to Earth at the DLR station in Neustrelitz. "We have to pick up extremely small signals," DLR scientist Peter Spietz says. The space agency is then able to calculate the path of the asteroids after collecting several days worth of data.
Small Budgets, But Considerable Responsibility
Spietz appears tense. He has to coordinate specialists from eight DLR institutes, all of whom are working on the project. The budget is comparatively small, but the responsibility is significant. The scientists also want to use the project to show that satellites can be built more cheaply and still remain reliable.
"We want to create price-effective projects, within shorter time frames," says Hansjörg Dittus, the head of the Institute of Space Systems in Bremen. The scientists hope that if the asteroid scout is successful, that they can use the same technology to build other types of observational satellites. They will be able to use the same substructure -- power, layout and communication systems -- to create other similar instruments.
Work on the asteroid project is expected to last three more years. The pressure on the scientists behind the satellite will be huge if it flops. But nobody wants to think about that. Specifications for the satellite's individual components are expected to be completed by the end of the year, but there is still plenty of work to do. Afterwards, AstroidFinder will be built and then tested under the strenuous conditions it would undergo in outer space: It will be shaken, frozen and irradiated.
How to Make AsteroidFinder Fly?
It is still unclear how AstroidFinder will be delivered to its orbit, between 650 and 850 kilometers above the Earth. DLR can either piggy back on another space mission or go the far more expensive route and purchase its own rocket. But that might be a small price to pay for a satellite that could help defend the planet from the deadly impact of an asteroid. Earth already bears scars -- in the form of craters -- all over its surface from previous asteroid assaults. And it would be prudent if we were able to predict the next impact before it happens.
One of the greatest examples of this kind of impact is the 300-kilometer wide Vredefort crater in South Africa, which was hit by one of the largest asteroids ever to strike earth, an estimated 2 billion years ago. The off-course asteroid that hit Mexico around 65 million years ago near what is today the town of Chicxulub was a little smaller -- yet many scientists believe it is implicated in the extinction of the dinosaurs.
Only a few days ago Italian researchers announced that they had found signs of yet another huge impact crater in Africa. Giovanni Monegato of the University of Padua and his colleagues believe that the 36 to 46-kilometer wide crater in central Africa is the result of an asteroid impact. The discovery itself is a result of work done in outer space: satellite pictures of rainforest that had been cut down in the Congo.
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