NASA's 'Lucy' is going to travel 4 billion miles to explore seven Trojan asteroids — and an asteroid Moon

• The National Aeronautics and Space Agency’s (NASA) Lucy Mission has a new target — a satellite orbiting an asteroid.
  
• Eurybates’ asteroid moon is estimated to be a kilometre wide.
  
• Exploring the newly discovered satellite will set a new cord of a spacecraft visiting 8 objects in one mission — it will also be the first to visit one of the smallest objects in the universe.
  

The National Aeronautics and Space Agency’s (NASA) Lucy Mission was already going to set a new record by visiting seven asteroids in a single mission when its team found a new target — an asteroid moon.

Set to launch in 2021, Lucy is going to travel over 4 billion miles to reach Jupiter’s orbit and find the Trojan asteroids — an ancient body of 60 rocks that share an orbit with the gas giant.

While conducting reconnaissance on their first target — Eurybates — the team was surprised to discover that the space rock had a companion. Data from the Hubble Space Telescope showed that there was another celestial body orbiting Eurybates.

The asteroid's little moon wasn’t easy to spot since Eurybates is 6,000 times brighter than its satellite. In fact, it took Lucy’s team three tries to confirm its existence.

Once the team was finally able to see it, the team determined that the satellite was only 1 kilometre across. If their estimate is correct, not only will Lucy be the first to visit eight celestial objects in one mission — it will also be the first to visit one of the smallest objects in the universe.

"While the current data are enough to confirm the existence of the satellite, the Lucy team will collect more HST data later this year to better understand the object’s orbit," remarks the Southwest Research Institute (SRI), home to the Lucy mission.

The Trojan asteroids

The Trojan asteroids are thought to be the cousins of the asteroid in the Kuiper Belt — home of the former planet, Pluto. Since its demotion, scientists have found that there are over 100,000 space rocks in the Kuiper Belt that larger than 100 kilometres in diameter.

Eurybates, on the other hand, is a little smaller measuring between 63 to 72 kilometres.

"Eurybates is considered the largest remnant of a giant collision that occurred billions of years ago. Simulations show that asteroid collisions like the one that made Eurybates and its family often produce small satellites," said Hal Levison, lead investigator of the mission.

To put it in perspective, the asteroid that wiped out the dinosaurs — and left the Chicxulub crater in its wake — is only estimated to be 10 kilometres wide.

After Lucy launched in 2021, it will take the spacecraft another six years to reach Eurybates. Currently, the fly-by is scheduled for 12 August 2027.

Lucy will approach the minor planet to a distance of around 1000 kilometres at a speed of 5.8 kilometres per second — 10 times the speed of a bullet shooting out of a rifle.

See also:
NASA's planet-hunter uncovers its first world with two stars 1,300 light-years away

NASA’s Sun probe sheds new light on our star — here are 5 new secrets it uncovered

NASA gets $35 million to make sure asteroids don't destroy Earth