Illustration of Lucy's passage by one of the Trojan asteroids close to Jupiter Southwest Research Institute/NASA
NASA's latest mission to study Trojan asteroids will launch from Cape Canaveral (Florida) on October 16th aboard an Atlas V rocket. These asteroids will be studied up close by the Lucy spacecraft, which will give us an insight into the formation of the solar system.
Two swarms of Trojan asteroids orbit the sun, sharing Jupiter's orbits like a police escort. One moves ahead of Jupiter, the other is just behind. These are the most beautiful relics of the early solar system. They are thought to be leftovers of the formation process for the outer planets.
They are held there by the gravitational effects of Jupiter and sun. This is why if an object is placed there early in the history of the solar system, it will be stable for ever, stated Hal Levison, Southwest Research Institute's mission leader, at a press conference in Texas on 13 October. These are the fossils that form planets.
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We have never been able to study the asteroids up close, despite their importance. Lucy will need to follow a complicated trajectory for 12 years in order to get there. To build momentum, the asteroid will fly by Earth twice to gain speed, and then it will head towards the largest swarm. It will pass a non-Trojan (52266) Donaldjohanson on its way to the leading swarm of asteroids in 2025. This is after Lucy, the famous fossilised skeleton from a human ancestor, for which the mission's name was given.
The spacecraft will inspect four Trojan asteroids once it reaches the leading group. One of them has its own moon. Lucy will finally fly past Earth and visit the two asteroids in 2033's trailing swarm. If all goes well, Lucy will fly back and forth between two Trojan clouds every six years, until the solar-powered spacecraft stops working.
Lucy is equipped with three major scientific instruments. One instrument will measure heat from the asteroids to determine their surface properties. The other will look at the light bouncing off of them to find out what they are made. A camera will capture detailed colour images.
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Lucy will travel to all three types of Trojans along its journey. These are distinguished by their reflectivity and colour. These three types could indicate that the asteroids were formed in different places. This information can help us to understand how the giant planets moved them to their current location.
Levison said that one of the most surprising things about the Trojans was their differences from one another when we first started studying them from the ground. Understanding the diversity of this population will help you understand how the planets formed. That is what Lucy was designed to do.
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