They launch a probe to study the place where the DART mission impacted, the first planetary defense test

() –– A European spacecraft and two shoebox-sized satellites were launched to study the aftermath of NASA’s DART mission, which intentionally crashed into an asteroid called Dimorphos and altered its orbit two years ago.

The European Space Agency’s (ESA) Hera mission lifted off aboard a SpaceX Falcon 9 rocket at 10:52 a.m. (Miami time) this Monday from NASA’s Kennedy Space Center in Florida. The launch marks the first Falcon 9 flight since another rocket in the same family experienced an anomaly during NASA’s SpaceX Crew-9 mission on September 29. The US Federal Aviation Administration is investigating the mishap and has cleared the Falcon 9 to return to flight for Hera only while the review is ongoing.

The spacecraft and its two companions are scheduled to CubeSat reach the asteroid Dimorphos and the largest asteroid it orbits, called Didymos, in late 2026. Together, the three spacecraft will conduct a “collision scene investigation” to solve the remaining mysteries about the double asteroid system, according to the ESA scientists.

NASA planned the DART (Double Asteroid Redirection Test) mission to conduct a large-scale evaluation of asteroid deflection technology for planetary defense. The agency wanted to see if a kinetic impact (such as a spacecraft colliding with an asteroid at 6.1 kilometers per second) would be enough to change the motion of a celestial object in space.

Neither Dimorphos nor Didymos pose a danger to Earth. Still, the double asteroid system was a perfect target to test deflection technology because Dimorphos’ size is comparable to asteroids that could threaten Earth.

Astronomers used ground-based telescopes to monitor the impact’s aftermath since the collision in September 2022, and determined that the DART spacecraft successfully changed the way Dimorphos moves, changing the lunar asteroid’s orbital period (or the time it takes to make a single revolution around Didymos) approximately 32 to 33 minutes.

But there are still many questions to be answered, such as whether the DART probe simply left a crater or whether its thrust completely changed the shape of Dimorphos. Determining the exact composition of the double asteroid system, as well as the consequences of the DART mission, could help space agencies further refine technology that could prevent asteroids from impacting Earth in the future.

“Hera will close the circle by providing us in detail with the final result of DART’s impact,” said Patrick Michel, research director at the French National Center for Scientific Research and principal investigator of the Hera mission.

When the Hera probe, the size of a small car, reaches the two-asteroid system in October 2026, it will be almost 195 million kilometers from Earth. Didymos is a mountain-sized asteroid with a diameter of 780 meters, while Dimorphos is similar in size to the Great Pyramid of Giza, with a diameter of 151 meters.

But first, Hera will pass by Mars in mid-March 2025, giving the spacecraft the extra boost needed to reach Didymos and Dimorphos two years after launch.

In addition to testing its suite of 11 instruments, Hera will fly 6,000 kilometers from the Martian surface. It will also observe one of the two moons of Mars, called Deimos, at a distance of 1,000 kilometers.

Scientists believe that the small, lumpy moons of Mars may be asteroids that were captured from the main asteroid belt, located between Mars and Jupiter. Hera flyby will capture data for the Japanese probe Martian Moons eXploration. That mission, which will be launched in 2026, will study both moons of the red planet and will land a small explorer on Phobos, to collect samples from that Martian moon that can be sent back to Earth.

Hera will then arrive in orbit of the Didymos system in October 2026 and spend six weeks observing both asteroids to learn more details about their shapes, masses, and thermal and dynamic flybys, while identifying points of interest for future closer flights.

After six weeks of exploration, Hera will launch its two CubeSats named Juventas, the Roman name for a daughter of Hera, and Milani, in honor of Andrea Milani, a mathematics professor at the University of Pisa, Italy, who died in 2018. Milani He is known for having created the first automated system to calculate the probabilities that an asteroid could impact Earth in the future.

Juventas is equipped with a radar instrument that will be able to look deep beneath the surface of space rocks, while Milani has a multispectral imager to map the minerals and dust on both asteroids. The instrument can capture a wider range of colors than the human eye can see to determine the composition of individual rocks and the dust environment that surrounds them.

The CubeSats, which have their own propulsion systems, will use inter-satellite links to communicate with Hera and transmit their findings to Earth, Michel said.

For 10 weeks, Hera will make observations that will bring her closer to the surface of the asteroids, up to 1 kilometer. Multiple flybys of the impact site created by DART on Dimorphos are expected.

Eventually, Hera could land on Didymos, which could serve as the end of its mission or a limited extension if it survives the landing, while CubeSats could make similar experimental landings on Dimorphos. Neither spacecraft is designed specifically for landing, but they will slow down enough to operate cameras and instruments on the asteroids after landing, according to the agency.

The most detailed views that humanity has had of the double asteroid system have been brief.

Images captured by DART and a small satellite called LICIACubewhich separated from the spacecraft to capture images of the collision and resulting cloud of debris, fueled much of the impact-related research published since September 2022.

But when Hera visits Dimorphos, she could look very different, Michel said.

“The most exciting thing for me is that, although we have magnificent images of Didymos, Dimorphos and their surface taken by the DRACO camera aboard the DART space probe before their collision, we already know that the same bodies and surface areas will have nothing to do with what those images showed us when Hera takes new images,” Michel said. “It still feels like we are discovering new worlds. And the great thing is that we will know why they are new or different, since DART provided us with all the initial conditions that led to their transformation,” he added.

The data collected by the mission could help scientists understand the internal structure of each asteroid. When DART crashed into Dimorphos, a plume of debris extended more than 10,000 kilometers into space and persisted for months, long enough to create the first man-made meteor shower that could be visible from Mars and Earth in the future. .

Scientists are eager to know whether Dimorphos is an asteroid made up of a pile of rubble held together by gravity with large voids inside, or a solid core surrounded by rocks and gravel, Michel said.

Mission scientists say understanding every possible aspect of Dimorphos is crucial because if an asteroid its size were to hit Earth, it could destroy an entire city.

While the DART mission was an “amazing success,” Michel said, Hera is necessary to understand the final outcome of the DART drift test and measure its efficiency.

“I hope this can provide a source of inspiration for other missions dedicated to planetary defense and solar system exploration,” he said.