The following asteroid collision is just a test


It’s never too early to plan ahead.

“There is no doubt that asteroids strike the earth and can cause great damage,” says Jay Apt, an astronaut who has flown four space shuttle missions, two as a team commander and who teaches engineering at Carnegie Mellon. “These strikes do not necessarily winter Earth for many years, although it is something to be taken very seriously.”

“But,” he continues, “once you see an asteroid come over here, the question is what to do about it.”

Scientists have debated that at least since Impact of the 1908 Toungouska, when an asteroid exploded over Siberia and, with the power of several atomic bombs, destroyed 80 million trees in a frozen area of ​​830 square miles. Astronomers have since counted 1,097,558 “rocky, airless remnants,” as NASA puts it, in our solar system. Sometimes one of them can enter Earth’s orbit, the prospect of which fuels the imaginations of science fiction writers alike astronomers’ nightmares.

Collision course

American science fiction writer Larry Niven once said, “Dinosaurs disappeared because they didn’t have a space program.

We do.

And now we have an interim response to the threat of a cataclysmic asteroid collision with our planet: NASA’s Double Asteroid Redirection Test, or DART.

Developed by a team of scientists from Johns Hopkins University Applied Physics Laboratory and the NASA Planetary Defense Coordination Office, DARD is an unmanned, remote-controlled astronomical suicide mission designed to push a half-mile-diameter asteroid out of orbit. Notice to the unfortunate: this is only a test. The asteroid in question, Didymos – Greek for “twin,” and so named because it was discovered to be associated with its own small moon – is not actually on a collision course with Earth.

Between Thanksgiving week (perhaps as early as the evening of November 23) and February 2022, the team behind DART will launch it from Vandenberg Space Force base in California on a SpaceX Falcon 9 rocket. The spacecraft, if all is right. passes as planned, will travel 6.8 million kilometers to reach and collide with Didymos’ moon, Dimorphos, which is 525 feet in diameter.

DART will also carry a spaceship the size of a shoebox provided by the Italian Space Agency. A few days before DART’s impact with Dimorphos, this small device, the LICIACube (Light Italian CubeSat for Imaging of Asteroids), will separate from DART to capture images of the impact.

The success will destroy DART but also provide data on how the collision alters the speed of the moon around its larger companion. The goal: to learn how to speed up or slow down the transit of an asteroid so that it can be remade if and when the asteroid in question is heading towards Earth.

An artist’s portrayal of NASA’s Double Asteroid Redirection Test spacecraft, which, if all goes well, will crash into an asteroid and drop it into a different orbit. NASA / NYT

A little bit of DART will make a huge difference.

“If you’ve known the orbit of an asteroid for a long time and have been warned in advance, and if you think it’s going to hit Earth, even a little nudge in the distance will change the path of the asteroid. and save the Earth, ”says Michael J. Neufeld, senior curator of the National Air and Space Museum.

But what if DART is a dud, or if the technology isn’t working quite well? Are we just to be the victims, to invoke the 1920 poem of the same name, fire and ice?

“We have other tools,” says Thomas D. Jones, a four-time space shuttle veteran and chair of the Association of Space Explorers’ Near-Earth Object Committee. “We can ‘park’ nearby and shoot the object through gravitational attractions. We can use a nuclear explosive device. And there is an exotic idea of ​​using a solar powered laser pulse to strike the asteroid repeatedly, creating a puff of gas that will vaporize a chunk of the surface and propel the asteroid like a rocket. But the physics of DART is simple: we just run into the object like we have car crashes on Earth. ”

Yes, simple.

Somehow, moving asteroids out of the way of Earth is a concern of astronauts such as Jones, whose committee believes there is a “100% chance that our planet will be hit again.” by a large NEO “and that there are up to 1,000” threats to human civilization “traveling near the planet.

In addition, there is this challenge: To gain support – technical, economic, political – for a global mobilization against an asteroid en route to Earth. As Kelly Fast, head of NASA’s Near-Earth Object Observation Program, said at an Association of Space Explorers seminar last week, “Planetary defense is a team sport.

Asteroid anxiety

Asteroids were first discovered on New Years Day 1801, in the early hours of the 19th century. In the decades since this discovery, science fiction writers have speculated on how Earthlings might redirect asteroids, perhaps to use them as resources, to produce rocket fuel, or even to use them for colonization. The real push to create planetary defense has come over the past half century. “There is a growing sense that we need to keep track of these things and see if we can do something to deflect them,” says Andrew Rivkin, a Johns Hopkins planetary researcher involved in the DART project.

Asteroid anxiety, in other words, is real.

So is the confusion over what exactly happens when an asteroid hits Earth’s atmosphere. In 2017, a team of researchers determined that cracks and pores on the surface of an asteroid let in high pressure air which creates massive internal pressure. Most asteroids explode from the inside before touching the Earth’s surface.

This has happened 26 times in the first 14 years of the 21st century. Sensors installed around Earth due to the Nuclear Test Ban Treaty Organization, which monitors the infrasound signature of nuclear detonations, have identified nuclear-force asteroid explosions, most of which have occurred in- over the oceans.

On February 15, 2013, however, a 66-foot-long asteroid traveling to 40,000 miles per hour exploded about 20 miles above Chelyabinsk, Russia. With a force 30 times that of the Hiroshima bomb, it damaged thousands of buildings in six cities and injured 1,500 people. Scientists widely believe that the destructive potential of an asteroid or other near-Earth object could exceed the regional disaster and be on a global scale.

Imagine what an asteroid with a diameter of half a mile, like Didymos, could do.

“A little safer”

The modern pioneers of asteroid deflection were scientists from the European Space Agency (ESA) who devised a dual spacecraft plan they called Don Quixote two decades ago. The mission would have deployed a spacecraft, Hidalgo, to crash into an asteroid, and a second, Sancho, to observe the change in momentum.

Faced with a lack of funding, Don Quijote failed to come out of the initial studies, which led to a 2010 report from the National Research Council in the United States, worryingly titled “”Defend Planet Earth. “He requested” an experimental test of a kinetic impactor as well as a characterization, monitoring and verification system, such as the Don Quijote mission which was previously envisaged but not funded by the European Space Agency. “

In 2018, ESA produced Hera, a smaller spacecraft that is expected to follow DART into deep space after five years to study the crater produced by DART.

DART’s mission is not an easy undertaking. While something his size would cause a huge explosion in Earth’s atmosphere, Dimorphos is actually quite small for celestial bodies. DART will move at around 4 miles per second, and in the spacecraft’s last four hours before the collision, scientists on the ground will cede direction of DART to autonomous on-board computers that will have a more than human-guided chance of smashing DART into the rock, thus pushing the asteroid out of its path.

The long-term effect of such efforts, according to Hopkins’ Rivkin, “is to make the planet a little bit safer.”

But not quite sure. There are other threats in space, such as comets rushing towards Earth at high speed. They can come from completely unexpected directions, and we cannot have any advance warning of their arrival. But that’s for another day, and another try.

Pleasant dreams!

David Shribman, former head of the Globe’s Washington bureau, is editor-in-chief of the Pittsburgh Post-Gazette and national columnist.

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