Home Latest News First mission to Jupiter's asteroids could reveal Solar System origins – Nature.com

First mission to Jupiter's asteroids could reveal Solar System origins – Nature.com

Ads

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
Advertisement
You can also search for this author in PubMed  Google Scholar
You have full access to this article via your institution.

The Lucy spacecraft, shown here in an artist’s rendering, will fly by six Trojan asteroids near Jupiter.Credit: NASA
A NASA spacecraft is about to begin its journey to a realm of the outer Solar System that has never before been visited: a set of asteroids orbiting the Sun near Jupiter. The rocks are “the last unexplored but relatively accessible population of small bodies” circling the Sun, says Vishnu Reddy, a planetary scientist at the University of Arizona in Tucson.
The US$981-million Lucy mission, set to lift off from Cape Canaveral, Florida, on 16 October, will spend the next 12 years performing gravitational gymnastics to swoop past six of the asteroids, known as Trojans, to snap photos and determine their compositions. Scientists think the Trojans will reveal information about the formation and evolution of the Solar System. The mission’s name reflects their hopes: Lucy is the 3.2-million-year-old hominid fossil unearthed in 1974 in Ethiopia that unlocked secrets of human origins.
Workers prepare the capsule that will protect the Lucy spacecraft during launch.Credit: NASA/Ben Smegelsky
The Trojans “are very mysterious, which makes them really fun”, says Audrey Martin, a planetary scientist at Northern Arizona University in Flagstaff, who works with the Lucy mission.
The asteroids probably formed in the outermost reaches of the Solar System around 4.6 billion years ago, when Earth, Jupiter and other planets were coalescing from a disk of gas and dust around the newborn Sun. In this scenario, gravitational interactions would have slung the Trojans inwards, where they now orbit as relatively pristine examples of the Solar System’s building blocks.
Scientists can study the Trojans to understand what the distant, primordial parts of the Solar System are like, without having to send a mission all the way out there.
Since 1991, when the Galileo spacecraft whizzed past the asteroid Gaspra on its way to Jupiter, a number of missions have explored the Solar System’s main asteroid belt, which lies between Mars and Jupiter. But no mission has ever gone to Jupiter’s Trojans, which might be very different from asteroids in the main belt. “Every time we go to new populations, we learn new things,” says Cathy Olkin, a planetary scientist at the Southwest Research Institute in Boulder, Colorado, and Lucy’s deputy principal investigator.
More than 7,000 Trojan asteroids travel near Jupiter, in two large swarms that lead and trail the planet as it orbits the Sun. Several other planets, including Mars and Neptune, also have Trojan asteroids that closely follow their orbits; Earth has at least two. But Jupiter has by far the most known Trojans.
This visualization shows how the Lucy spacecraft (blue) will launch from Earth (green) and then loop around the Solar System for 12 years to visit Trojan asteroids in Jupiter’s orbit (orange). It will fly by one main-belt asteroid (white dot orbiting between Mars and Jupiter), and visit six Trojans in the swarms around Jupiter (white dots; one of them is a binary asteroid comprised of two large objects).Credit: NASA’s Scientific Visualization Studio
When the Solar System formed, according to a leading model of planetary formation, the planets were much closer to the Sun than they are today. Gravitational interactions then caused many of them to migrate. Saturn, Uranus and Neptune moved outwards from the Sun, while Jupiter moved slightly inwards. In this chaos, icy bodies from the Solar System’s outermost reaches — the Kuiper Belt, where Pluto and other small objects orbit today — got tossed inwards. Jupiter captured them, and they have remained nearby ever since, essentially unaltered for billions of years. That makes them an important part of understanding the origin and evolution of the Solar System, says Lori Glaze, director of NASA’s planetary-science division at the agency’s headquarters in Washington DC.
Perhaps because of their turbulent origin, the Trojan asteroids — named after characters in Homer’s epic poem the Iliad — have a wide variety of colours, shapes and sizes1. Lucy will visit six of them in an effort to determine why they are so diverse2. The spacecraft’s targets include Eurybates, a 64-kilometre-wide remnant of a massive cosmic collision, and its tiny moon Queta, discovered last year with the Hubble Space Telescope3. Others are the 20-kilometre-long, football-shaped Leucus, and the pair known as Patroclus and Menoetius, which orbit one another and are both around 100 kilometres across. Such binary asteroids are common in the Kuiper Belt, but not, as far as scientists can tell, among Trojans.

NASA ‘fist bumps’ an asteroid to reveal Solar System’s secrets
After launch, Lucy will make several loops past Earth to gain the gravitational boost needed to head towards its first target, Eurybates, which it won’t reach until 2027. The final flyby, of Patroclus and Menoetius, won’t happen until 2033. “You definitely have to be patient when you’re trying to explore the outer Solar System,” Olkin says.
Powered by two 7.3-metre-wide solar panels, Lucy will whiz past each asteroid at 6 to 9 kilometres per second, taking measurements including the asteroid’s colour, composition, spin and mass4. Whatever the mission finds will almost certainly rewrite textbook entries on the Trojan asteroids, Reddy says. “We might throw all our formation models out the window.”
doi: https://doi.org/10.1038/d41586-021-02807-w
Sharkey, B. N. L. et al. Astron. J. 158, 204 (2019).
Article  Google Scholar 
Levison, H. F. et al. Planet. Sci. J. 2, 171 (2021).
Article  Google Scholar 
Brown, M. E. et al. Planet. Sci. J. 2, 170 (2021).
Article  Google Scholar 
Olkin, C. B. et al. Planet. Sci. J. 2, 172 (2021).
Article  Google Scholar 
Download references
The Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Brisbane or Canberra, Australia
Dana-Farber/Boston Children's Cancer and Blood Disorders Center
Boston, MA, United States
University Health Network (UHN), U of T
Toronto, Ontario, Canada
Hospital for Special Surgery (HSS)
New York, NY, United States
You have full access to this article via your institution.

Ads

An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday.
Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.
Advanced search
Nature (Nature) ISSN 1476-4687 (online) ISSN 0028-0836 (print)
© 2022 Springer Nature Limited

source

Ads
Previous articleWhy the crypto market crash may play in Bitcoin's favour – Cointelegraph
Next articleWindows 11 'Restore Apps' feature will make it easier to set up new PCs – BleepingComputer
Abhinav Breathes and Bleeds Technology. He's a humanoid with a passion for Gadgets, Cars, Gaming. You can usually find him on PSN Blabbering about his FIFA skills.