The Hera spacecraft mission, proposed by the European Space Agency, is heading to a binary asteroid to support NASA's planetary defense plan against potential asteroid collision.

NASA's Double Asteroid Redirection Test or DART mission is scheduled to ram with a binary asteroid in October 2022 and then again on 2024. After the impact, all connections to the binary asteroid will stop, and essential information will be missing. At this point, the spacecraft Hera will then be heading to the location to measure all possible effects of NASA's intentional collision with the asteroid.

The Hera spacecraft is scheduled to reach the target in 2026. By this time, NASA's DART had historically altered the duration of the orbit of the target asteroid.

The Binary Asteroid

The mission's target is a pair of Near-Earth asteroids called Didymos. It is consists of two bodies: the Didymos A or what is informally called the Didymain which measures about 2,560 feet; and the Didymos B or what is informally called as the Didymoon which measures about 530 feet. In comparison, the latter is about the same size as the Great Pyramid of Giza.

The mass of other planetary bodies can be measured by calculating their gravitational pull on a spacecraft. However, this method will not work with the Didymos because Didymoon's gravitational field will be overpowered by the Didymain.

Hence, Didymoon, which is orbiting Didymain, is the primary focus of the Hera spacecraft mission. After DART's impact to Didymoon, Hera will survey its mass, the shape of the crater created by the collision, and its physical, and dynamical properties. The Hera spacecraft will also be deploying Europe's first deep space CubeSats.

"Such a binary asteroid system is the perfect test bed for a planetary defense experiment but is also an entirely new environment for asteroid investigations," said Ian Carnelli, mission manager for the Hera spacecraft. He added that binary asteroids comprised about 15 percent of all identified asteroids but binaries had never been explored before.

Didymoon will become the smallest asteroid to be visited and Hera faces the challenge of performing high-resolution visual, laser, and radio science mapping of both its exterior and interior surface.

Hera Spacecraft Mission

All images and relevant data to be acquired by Hera will then be used to analyze Didymain. For one, Didymain's mass can be calculated with about 90 percent accuracy by measuring the wobble that Didymoon causes the Didymain.

"This key data gathered by Hera will turn a grand but one-off experiment into a well-understood planetary defense technique: one that could in principle be repeated if we ever need to stop an incoming asteroid," Carnelli added.

On June 25, ESA announced that Hera has entered its next engineering design phase.

Potential Asteroid Collision

To date, DART has passed its preliminary design review and NASA is about to begin its designing process. The mission specifically involved testing a planetary defense strategy called the "kinetic impactor technique" which involves striking the asteroid to shift its orbit. This strategy is the best possible means to defend Earth from future asteroid impact.

ESA's update on Hera comes after NASA's announcement made last week about the National Near-Earth Object Preparedness Plan. The plan, which was originally released by the White House, detailed steps that government and the space agency would implement in an event that an asteroid hits Earth.

Early this week, a study, which analyzed data from 2013 to 2016, found that there could still be thousands of unconfirmed NEOs that are approaching Earth. The study called for concerned parties to devise an accurate statistical data of these unconfirmed space objects. Indeed, on June 21, an asteroid exploded over Russia and NASA was unable to detect it until after its impact.

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