US space agency launched a mission late on Tuesday night from California that will deliberately attempt to smash a spacecraft into an asteroid. The DART mission is like a test run should the need arise in the future to stop a giant space rock from colliding with Earth.
DART (Double Asteroid Redirection Test) is a real proof-of-concept experiment that blasted off at 10:21 pm Pacific Time Tuesday, aboard a SpaceX rocket from Vandenberg Space Force Base in California.
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The goal is to slightly alter the trajectory of Dimorphos, a "moonlet" around 525 feet (160 meters, or two Statues of Liberty) wide that circles a much larger asteroid called Didymos (2,500 feet in diameter). The pair orbit the Sun together, an AFP report explains.
Impact should take place in the fall of 2022, when the binary asteroid system is 6.8 million miles (11 million kilometers) from Earth, almost the nearest point they ever get. "What we're trying to learn is how to deflect a threat," NASA's top scientist Thomas Zuburchen said of the $330 million project, the first of its kind.
The asteroids in question pose no threat to our planet. But they belong to a class of bodies known as Near-Earth Objects (NEOs), which approach within 30 million miles.
NASA's Planetary Defense Coordination Office is most interested in those larger than 460 feet in size, which have the potential to level entire cities or regions with many times the energy of average nuclear bombs.
There are 10,000 known near-Earth asteroids 460 feet in size or greater, but none has a significant chance to hit in the next 100 years. However, scientists think there are still 15,000 more such objects waiting to be discovered.
15,000 mph kick
Planetary scientists can create miniature impacts in labs and use the results to create sophisticated models about how to divert an asteroid -- but models are always inferior to real world tests.
Scientists say the Didymos-Dimorphos system is an "ideal natural laboratory," because Earth-based telescopes can easily measure the brightness variation of the pair and judge the time it takes the moonlet to orbit its big brother.
Since the current orbit period is known, the change will reveal the effect of the impact, scheduled to occur between September 26 and October 1, 2022. What's more, since the asteroids' orbit never intersects our planet, they are thought safer to study, the AFP report adds.
The DART probe, which is a box the size of a large fridge with limousine-sized solar panels on either side, will slam into Dimorphos at just over 15,000 miles an hour.
Andy Rivkin, DART investigation team lead, said that the current orbital period is 11 hours and 55 minutes, and the team expects the kick will shave around 10 minutes off that time.
There is some uncertainty about how much energy will be transferred by the impact, because the moonlet's internal composition and porosity are not known. The more debris that's generated, the more push will be imparted on Dimorphos. "Every time we show up at an asteroid, we find stuff we don't expect," said Rivkin.
The DART spacecraft also contains sophisticated instruments for navigation and imaging, including the Italian Space Agency's Light Italian CubeSat for Imaging of Asteroids (LICIACube) to watch the crash and its after-effects.
"The CubeSat is going to give us, we hope, the shot, the most spectacular image of DART's impact and the ejecta plume coming off the asteroid. That will be a truly historic, spectacular image," said Tom Statler, DART program scientist.
Earlier this year, Reuters reported that Chinese researchers were deciding on sending more than 20 of China's largest rockets to practice turning away a sizable asteroid. At China's National Space Science Center, researchers found in simulations that 23 Long March 5 rockets hitting simultaneously could deflect a large asteroid from its original path by a distance 1.4 times the Earth's radius, the Reuters report explained. These simulations and calculations were based on an asteroid dubbed Bennu.
(With inputs from AFP and Reuters)
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