In humanity’s latest bid to avoid going the way of the dinosaurs, a European spacecraft soared away from the coast of Florida on Monday. The mission, Hera, will visit an asteroid that NASA deliberately struck with another spacecraft two years ago.
The car-size orbiter launched from Cape Canaveral on a SpaceX Falcon 9 rocket at 10:52 a.m. Eastern time against a backdrop of gray, cloudy skies. Led by the European Space Agency, Hera is the latest spacecraft to join a global effort to build a strategy for defending our planet from hazardous rocks in space.
“If we are not able to protect our planet, then that would be the end of humankind, the end of the Earth we know,” said Walther Pelzer, director general of DLR, the space agency of Germany, one of ESA’s member states.
With Hurricane Milton’s landfall on Florida’s Gulf Coast imminent, Pelzer added that he felt relieved to see the launch go off without a hitch.
Sci-fi aficionados have long imagined that the threat of an asteroid or comet hurtling toward our planet would be annihilated via nuclear explosion, as evidenced by films like “Armageddon,” “Deep Impact” and, more recently, “Don’t Look Up.” But scientists have found that a more viable — though much less dramatic — plan for avoiding Earth’s destruction is simply to knock a looming rock out of the way, a method known as kinetic impact deflection.
In 2022, NASA demonstrated for the first time that it was possible to alter the path of an asteroid with a mission called the Double Asteroid Redirection Test, or DART. The target of the mission’s primary spacecraft was an asteroid named Dimorphos, a 495-foot-wide object orbiting an even bigger rock named Didymos. Neither body posed a threat to Earth, but the binary asteroid system was close enough to Earth for the impact to be studied by observatories on the ground.
DART slammed into Dimorphos at more than 14,000 mph, its camera transmitting a final, partial image of the asteroid’s cobbled surface just before the impact. The strike sent a dusty cloud of debris and boulders thousands of miles into space. The collision shortened the asteroid’s orbit around its parent body by 33 minutes — well over the 73-second goal set by NASA.
“I see DART as being just the start,” said Nancy Chabot, a planetary scientist at Johns Hopkins University and DART’s coordination lead. “A smashing start, one might even say.”
Hera is Phase 2.
Patrick Michel, the principal investigator of the mission, calls Hera “a detective” that will determine what the properties of Dimorphos are, how efficient the DART mission was and how to make deflecting a killer asteroid a regular tool in the world’s planetary defense arsenal.
And while Michel admits that the risk of catastrophic destruction by way of asteroid is low, unlike that caused by other natural disasters that plague life on Earth, “we have the possibility to do something about it,” he said. “The dinosaurs would have liked to have a space agency.”
Five days after launch, Hera will test out the capabilities of its scientific instruments by observing the Earth and the moon, according to Michel. Next March, it will swing by Mars and its smallest moon, Deimos. That encounter will give Hera the extra thrust it needs to reach its final destination.
When it reaches Didymos and Dimorphos by October 2026, Hera will be 121 million miles from Earth.
While circling the binary system, the spacecraft will spend up to six months gathering data using a suite of onboard instruments, including optical cameras, a spectrometer to probe the composition of Dimorphos and a thermal imager to measure the asteroid’s surface temperature. As Hera transmits data back to Earth over a high-gain antenna, the mission’s scientists will also use small shifts in signal frequencies caused by Dimorphos’ gravity to determine the asteroid’s shape and mass.
The mission will also deploy two mini satellites, or CubeSats. One, Juventas, will use radar sounding to probe the interior structure of Dimorphos. The second, Milani, will image the asteroids and survey the dust surrounding the pair.
All these details will help scientists understand how the properties of an asteroid affect its trajectory, and how it will respond to an impact — as well as how big and fast a spacecraft needs to be to deflect it.
Scientists are also curious to learn what, exactly, DART did to Dimorphos. Did it leave a small crater, or was the asteroid completely reshaped, as one study suggests?
“Each time we’ve interacted with an asteroid so far, the reaction was not the one we expected,” Michel said. When OSIRIS-REx, a NASA spacecraft that brought home an overflowing canister of space rock, punched into an asteroid, it was like “going into melted butter,” he added.
And though the primary goal of Hera is planetary defense, the data “is going to enable amazing science,” said Jean-Baptiste Vincent, a scientist at the German Aerospace Center’s Institute of Planetary Research.
Hera’s measurements will lend insight into how binary asteroid systems form and what their environment is like. The spacecraft will also provide the first up-close observation of a rapidly spinning asteroid like Didymos, which rotates 10 times faster than Earth.
At the tail of the mission, Hera’s CubeSats will try to land on Dimorphos to measure its local gravity and surface dust. Hera itself may also attempt a landing on Didymos, to send back images from one of its poles.
Hera is far from the end when it comes to bolstering humanity’s planetary defense readiness. Along with the ability to deflect an asteroid out of harm’s way, scientists also need to know what’s coming toward Earth.
Sky trackers around the world have spotted nearly all near-Earth objects wider than about 0.6 miles in diameter, according to Matthew Payne, director of the Minor Planet Center at the International Astronomical Union. An asteroid of that size is big enough to most likely cause billions of deaths, he said. But only about one-third of smaller bodies near Earth like Dimorphos — sizable enough to cause considerable damage to the planet and its inhabitants — have been discovered so far.
“Finding the asteroids, tracking the asteroids, that’s always the foundation of planetary defense,” Chabot said. “These things have to work together.”
This article originally appeared in The New York Times.
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