The uncertainty surrounding the recent meteorite impact in Peru highlights the need to know more about these pieces of natural space debris and their trajectories, and gives the European Space Agency's planned mission Don Quixote and other, similar missions, a keen sense of urgency.
The ESA's mission follows the recent announcement by British scientists devised a plan to send a probe to study the asteroid named Apophis which is feared will be diverted in to a planetary collision course with Earth on April 13, 2036. And though the science is sketchy behind this precise calculation, and the likelihood of impact then, later, or not at all, is simply unknown, the plans being readied by space organizations and scientists across the planet are reassuring, if nothing else.
In the photo, people in southern Peru gaze at a crater made by a meteorite on September 17th. Villagers were struck by a mysterious illness after the meteorite crashed to Earth in their area, regional authorities said Monday. Around midday, villagers were startled by an explosion and a fireball that many were convinced was an airplane crashing near their remote village, located in the high Andes department of Puno in the Desaguadero region, near the border with Bolivia. Residents complained of headaches and vomiting.
In 1908, a 20-meter asteroid impacted the uninhabited Tunguska forest in Siberia, toppling trees and causing total devastation over an area of two thousand square kilometers. Scientists predict this type of event to occur about every 150 years. Next year's 100th anniversary of that impact will be yet another reminder of the need to learn about and become ready to deal with asteroids – even the small ones.
Recent studies showed that it is probably the smaller pieces of rock, at most a few hundred meters across, rather than the larger ones that are the cause of most concern. A worldwide network of astronomers is currently cataloging larger objects above 1 km in diameter. A number of survey telescopes have taken up the challenge to detect as many as 90 percent of all near Earth objects down to a size of 140 meters by around 2020. Only after this time will we know whether lunar and space-based observatories will be needed to find the rest.
Part of the trouble with these small chunks of rock is getting a solid fix on their orbits. From the ground, it is very difficult – sometimes impossible – to determine their trajectory with enough precision to rule out impacts with our planet in the years to come. ESA teams have been concentrating on a mission to actually 'mark a cross' on small asteroids and check the state of the art of our technology. The Don Quixote mission has two phases: In the first phase, a spacecraft would rendezvous with an asteroid and go into orbit around it. It would monitor the asteroid for several months, precisely determining its position, shape, mass and gravity field.
In the second phase, another spacecraft would slam into the asteroid at a speed of around 10 km/s, while the first spacecraft watches, looking for any changes in the asteroid's trajectory. In this way, a mission involving two spacecraft would attempt to be the first to actually move an asteroid.
In its current design, the first phase spacecraft, Sancho, could reach any one of five or six small, nearby asteroids. Each one is no larger than a few hundred metres in diameter. At present, the mission planners have chosen to concentrate on Apophis, a small asteroid that can swing dangerously close to Earth on the outwards stretch of its orbit around the Sun.
Don Quixote could launch sometime early in the next decade. Sancho would take some 25 months to reach its target.
"The idea is to get the technology ready before you really need it," says Ian Carnelli, Technical Officer for the Don Quixote mission at ESA.
If the past is prelude, there's bound to be a massive collision
event from a rogue asteroid at some point in the near future unless we
successfully intervene. The bulk of the
terrestrial impact craters that were ever formed beyond the existing 160 known large-impact craters on the planet have been
obliterated by eons of geological processes.
A NASA program called the Spaceguard Survey to track the largest potentially hazardous objects of the 20,000 asteroids and comets orbiting relatively close to our planet greater than 3,300 feet in diameter that could devastate most life if they hit.
Donald K. Yeomans, director of the Spaceguard program, said that there were believed to be 1,100 of these larger objects and that the survey had cataloged about 73 percent of them. The initial goal of tracking 90 percent of them should be reached by 2010, more than a year later than originally planned.
In a note of cosmic irony, that which might eventually destroy us may also have been responsible for the origins of life on our planet.
In 2011, NASA will launch the OSIRIS mission to a menacing asteroid called RQ36,which would barely be noticed "except" says Joseph Nuth of NASA's Goddard Space Flight Center, "that It's a treasure trove of organic material, so it holds clues to how Earth formed and life got started, and it regularly crosses Earth's orbit, so it might impact us someday." RQ36 is roughly about two-fifths of a mile in diameter. It orbits between about 83 million and 126 million miles from the sun, swinging within about 280,000 miles of Earth orbit, or roughly 40,000 miles more distant than the moon.
"OSIRIS of Egyptian mythology is the god of life and fertility, the god who taught Egyptians agriculture," said Dante Lauretta, OSIRIS Deputy Principal Investigator. "There's an analogy to the proposed 21st century space mission. We're looking at the kind of object that we think brought life to Earth; that is, objects that seeded Earth with early biomolecules, the precursors of life."
The mission will also help to better track the orbits of asteroids that might hit Earth by accurately measuring the "Yarkovsky effect" for the first time. The Yarkovsky effect is a small push on an asteroid that happens when the asteroid absorbs sunlight and emits heat. The small push adds up over time, and it is uneven due to an asteroid's various surface materials, wobble, and rotation. There's no sure way to predict an Earth-approaching asteroid's orbit unless you can factor in how the Yarkovsky effect will change that orbit.
“The threat of the Earth being hit by an asteroid is increasingly being accepted as the single greatest natural disaster hazard faced by humanity,” says Nick Bailey of the University of Southampton's School of Engineering Sciences team, who developed the identifying program.
The team used raw data from multiple impact simulations to rank each country based on the number of times and how severely they would be affected by each impact. The software, called NEOimpactor (from NASA's "NEO" or Near Earth Object program), has been specifically developed for measuring the impact of 'small' asteroids under one kilometer in diameter.
Early results indicate that in terms of population lost, China, Indonesia, India, Japan and the United States face the greatest overall threat; while the United States, China, Sweden, Canada and Japan face the most severe economic effects due to the infrastructure destroyed.
The top ten countries most at risk are China, Indonesia, India, Japan, the United States, the Philippines, Italy, the United Kingdom, Brazil and Nigeria.
Posted by Rebecca Sato and Casey Kazan.
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