In the first experiment of its kind, NASA is set to hit a small, harmless asteroid millions of miles away.
A space probe called Dart will head toward the asteroid on Monday to crash directly into it at 14,000 miles per hour (22,500 kilometers per hour). The impact should be enough to push it into a slightly lower orbit around another larger asteroid to show that if a huge space rock were ever headed for our planet, we have a chance to defend ourselves by deflecting it.
“This is stuff from science fiction books and cheesy ‘StarTrek’ episodes from when I was a kid, and now it’s real,” NASA program scientist Tom Statler said Thursday.
Cameras and telescopes will observe the collision, but we will have to wait days or even weeks to find out if it really changed the orbit. The $325 million planetary defense test began with the launch of Dart last fall.
The asteroid being targeted is called Dimorphos and is about 9.6 million kilometers (7 million miles) from Earth. It is quite small, about 160 meters (525 feet) in diameter, and accompanies a larger asteroid, Didymos, which is Greek for twin and measures about 780 meters (2,500 feet). Discovered in 1996, Didymos spins so fast that scientists think it has blown off material that formed its moon, Dimorphos, which orbits it less than a mile (1.2 kilometers) away.
“This is really about asteroid deflection, not disruption,” said Nancy Chabot, a planetary scientist and mission team leader at the Johns Hopkins University Applied Physics Laboratory, which manages the initiative. “This is not going to destroy the asteroid. It’s not going to turn it into a bunch of shards,” she noted. Instead, the impact will create a crater tens of meters wide and hurl a million kilograms (about two million pounds) of rock and dust into space.
NASA insists that there is no chance that any of the asteroids will pose a danger to Earth now or in the future. That is why they were chosen.
DART, THE IMPACTOR
The Johns Hopkins Laboratory took a minimalist approach to the development of Dart, short for Double Asteroid Redirection Test, as it is essentially a battering ram that will be totally destroyed. It has only one instrument: a camera used to navigate, select the target and record its last action. Dimorphos, believed to be basically a pile of debris, will appear as a point of light about an hour before impact, and will look larger and larger in images the camera will transmit back to Earth. The administrators are confident that Dart will not accidentally crash into the larger Didymos. The probe’s navigation system is designed so that the spacecraft distinguishes between the two asteroids and, in the last 50 minutes, heads towards the smaller one.
The probe, which is the size of a vending machine and weighs 570 kilograms (1,260 pounds), will collide with the 5 billion kilogram (11 billion pound) asteroid.
“Sometimes we say it’s like crashing a golf cart at high speed into a Great Pyramid,” Chabot said.
Unless Dart misses the target, which NASA says has less than a 10% chance of happening, Dimorphos will spell the end of the probe. If it goes by, Dart will meet both asteroids again in a couple of years for a second chance.
SAVING THE EARTH
Little Dimorphos completes one lap around big Didymos every 11 hours and 55 minutes. With the impact of Dart the time should be reduced by about 10 minutes. Although the collision will be immediately apparent, it could take a few weeks or more to verify the alteration in the minor moon’s orbit. Cameras on board Dart and an accompanying minisatellite will capture images of the collision at very close range.
Telescopes on Earth’s seven continents, as well as the Hubble and Webb space telescopes, and NASA’s Lucy spacecraft studying asteroids, may see a bright flash when Dart collides with Dimorphos and sends a torrent of rock and dust into the sky. space. The observatories will track the asteroid pair in its orbit around the Sun to see if Dart altered Dimorphos’s orbit. In 2024, a European probe called Hera will follow Dart’s journey to measure the results of the impact.
Although the desired push should slightly change the smaller asteroid’s position, that will result in a larger change over time, according to Chabot.
“So if you were to do this for the defense of the planet, you would have to do it five, 10, 15, 20 years in advance for this technique to work,” he said. Even if Dart fails, the experiment will provide valuable insights, said Andrea Riley, a NASA program executive. “That’s why we’re doing the test. We want to do it now and not when it is really needed, ”she pointed out.
PLENTY OF ASTEROID MISSIONS
Planet Earth is on an asteroid hunt. NASA has collected about 450 grams (one pound) of debris from asteroid Bennu and is bringing it back to Earth. The cargo should arrive next September. Japan was the first to bring back asteroid samples, achieving the feat a couple of times. China hopes to follow suit by sending a mission in 2025.
NASA’s Lucy probe, meanwhile, is headed for asteroids near Jupiter after its launch last year. Another probe, Near-Earth Asteroid Scout, has been placed on NASA’s new lunar rocket awaiting liftoff; will use a solar sail to pass close to an asteroid smaller than 18 meters (60 feet) next year. In the coming years, NASA also plans to send a telescope into space that will take a census to identify hard-to-find asteroids that could pose a threat.
An asteroid mission remains stalled while an independent review board assesses its future. NASA’s Psyche probe was supposed to be sent into space this year toward a metal-rich asteroid between Mars and Jupiter, but the team was unable to test the flight software in time.
For decades, Hollywood has produced dozens of movies about killer asteroids, including 1998’s “Armageddon,” in which Bruce Willis was flown to Cape Canaveral for filming, and last year’s “Don’t Look Up,” in which Leonardo DiCaprio has the title role in an all-star cast.
Lindley Johnson, head of planetary defense at NASA, says he has seen them all since 1979’s “Meteor,” his personal favorite “since Sean Connery played me.” Although some of the sci-fi movies are more accurate than others, he noted, the entertainment always wins out.
The good news is that there seems to be no danger for the next century, with no known threats. Otherwise “it would be like in the movies, right?” said NASA science mission chief Thomas Zurbuchen.
However, what is worrying are the unknown threats. The location of less than half of the 140-meter (460-foot) objects has been confirmed, with millions of smaller but still dangerous objects still moving at full speed.
“These threats are real and what makes this time special is that we can do something about it,” Zurbuchen said.
Not by destroying an asteroid like Willis’s character did—that would be a last-minute resort—or begging heads of government to take action like DiCaprio’s character did to no avail. If time permits, the best tactic would be to divert the threatening asteroid from our trajectory, as will be done with the Dart experiment.
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Source: El Nuevo Herald