In recent years, films such as “Armageddon” and “Deep Impact” have shown asteroids threatening the Earth and shown the devastating effects of impacts. Planetary defense efforts and the possibility of such events are more than just science fiction.
NASA and the European Space Agency (ESA) have been working together to understand the potential dangers of asteroids and other near-Earth objects. They’ve also taken specific steps to protect us if a dangerous asteroid does hit us.
DART planetary defense mission deflects asteroid
On November 24, 2021, NASA launched the Double Asteroid Redirect Test (DART) using a Falcon 9 rocket from Vandenberg Air Force Base. The goal of this planetary defense program is to hit an asteroid with a high-speed moving spacecraft in an attempt to change its orbit and deflect it away from Earth.
DART also carries a small satellite from the Italian Space Agency (ASI). This is the Italian Lightweight CubeSat (LICIACube) for asteroid imaging. It’s about the size of a shoe box. It detached from DART days before impact.
The target of the DART mission is the Dimorphos moon, which orbits the larger asteroid Didymos. Dimorphos is about 6.8 million miles from Earth, and neither object poses a threat to Earth, but they are relatively close given the distance between objects in space. Didymos is about half a mile in diameter and Dimorphos is about 525 feet in diameter.
DART arrived at the Didymos system on September 26, 2022, and recorded images from the seconds before impact. The images were able to pinpoint the exact impact site to within one meter. DART impacted Dimorphos at 7:14 p.m. and sent a signal confirming a successful impact with Earth 38 seconds later. DART was traveling at about 14,000 miles per hour at the time of impact.
Detailed images from satellites and telescopes provide proof of DART mission success
this LICIACube is capable of capturing detailed images Demofors before and just three minutes after impact. These show the debris surrounding Dimorphos after the collision, an important confirmation of the success of this planetary defense program.
The task then turned to analyzing the impact of the collision. Since DART hit Dimorphos, astronomers have been observing it using ground-based telescopes, LICIACube and the Hubble Space Telescope. Their investigation confirmed that DART indeed altered Dimorphos’ orbit around Didymos.
“This result is an important step toward understanding the full impact of DART on its target asteroid impacts,” said Lori Glaze, director of NASA’s Planetary Science Division at NASA Headquarters in Washington.
European Space Agency launches HERA mission to study DART impact
For follow-up observations of DART, ESA launched the Hera mission on October 7, 2024, to revisit Didymos and Dimorphos. Hera, dubbed “Europe’s flagship planetary defender” by ESA, was launched from Cape Canaveral on a Falcon 9 rocket.
Hera should arrive on Didymos systems in January or February 2027. Scientists hope it will provide important information useful for future planetary defense efforts.
Hera mission’s Mars booster
The trip will require several complex maneuvers, including a pass within about 3,100 miles of Mars. This would use Earth’s gravity to accelerate the spacecraft.
“We were very lucky that Mars was in the right place at the right time to lend a helping hand to Hera,” said Pablo Muñoz, ESOC Mission Analysis Teamwho planned Hera’s journey. “This allows us to design an orbit that uses Mars’ gravity to accelerate Hera toward Didymos, saving significant fuel for the mission and allowing Hera to reach the asteroid months earlier than would otherwise be possible.”
Hera will check the impact of DART tasks
Once Hera reaches the Didymos system, it will begin a series of close observations. It will perform five observation passeseach getting closer and closer to the surface of Didymos. During its fourth flyby, Hera will fly at an altitude of about 3,100 feet above the ground and eventually land on Dimorphos.
During the mission, Hera will examine the density and shape of Didymos and Demophos. It will also observe changes in Dimorphos’ motion and orbit and scrutinize DART’s impact crater.
European center maintains near-Earth object data
All of this work looking at ways to protect Earth from asteroids and other celestial bodies is based on real data. In recent years, ESA has been tracking objects under its Near Earth Object Coordination Center (NEOCC)the operations center of its Planetary Defense Office. It collects information from telescopes and other sensors.
NEOC is located at the ESA ESRIN site in Frascati, Italy. It is the central access point for the entire European network of NEO data sources. NEOC uses the data to study orbits, monitor impacts and analyze potential risks. This includes providing countries with timely data on objects approaching Earth.
Near-Earth objects are asteroids or comets that pass close to Earth’s orbit. This means it is about 28 million miles from Earth’s orbit. NEOCC also has a website that provides the latest information and statistics on the asteroid population, upcoming close flybys, and the ESA Asteroid Risk List.
As of In November 2024, there are more than 1,200,000 asteroids in the solar system. More than 36,000 are near-Earth objects, of which more than 1700 are on ESA risk listwhich means they deserve close monitoring. This provides critical information for all international planetary defense efforts.
Video shows HERA’s planetary defense mission to the Didymos asteroid system. Image source: European Space Agency
