The Dawn spacecraft is now very close to the dwarf planet Ceres, but there are some interesting new findings from its previous visit to the asteroid Vesta. Curved gullies on its surface suggest that small amounts of water may have once been present in the form of wet debris flows—a rather surprising discovery.
Solar systems, including ours, are thought to begin as massive clouds of dust and gas surrounding young stars; over billions of years, planets form from repeated impacts of rocky debris. Asteroids and comets are left-over chunks of debris from that process which didn’t coalesce together. Such debris clouds, or protoplanetary disks, have been found around many young stars. These are solar systems still in their infancy. Now, astronomers have been able to observe the actual collision between two large rocky bodies, most likely asteroids, in a protoplanetary disk surrounding a young, Sun-like star 1,200 light-years away.
When it comes to planetary rings, what do you think of? Saturn is the first obvious thing that comes to mind, with its famous majestic ring system surrounding the gas giant planet. The other gas and ice giants – Jupiter, Uranus and Neptune – also have rings, although not as spectacular as Saturn’s. The smaller rocky planets in our solar system are all lacking rings unfortunately. But now, a new set of rings has been discovered for the first time – not around a planet, but an asteroid!
The Dawn spacecraft left behind the giant asteroid Vesta last September, and is now en route to the even bigger dwarf planet Ceres, but scientists are still busy studying all of the data that was sent back to Earth while it was orbiting Vesta for over a year. And as often happens while exploring these new worlds, they have made a surprising discovery: long, sinuous gullies on the walls of geologically younger craters.
With all of the news lately about the landing of the Curiosity rover on Mars, it might be easy to forget about the other missions currently going on all over the solar system. That includes the asteroid belt, where the Dawn spacecraft has been orbiting and studying the giant asteroid Vesta since July of last year, sending back incredible photos and information about this unique world.
But now, Dawn has departed from Vesta to continue its mission elsewhere; on September 4, it escaped Vesta’s gravitational pull and is now headed for its next rendezvous – the dwarf planet Ceres. It is expected to arrive there in early 2015, the same year that the New Horizons spacecraft will finally reach Pluto.
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In 2010, the Japanese spacecraft Hayabusa completed an exciting although nail-biting mission to the asteroid Itokawa, successfully returning samples to Earth after first reaching the asteroid in 2005; the mission almost failed, with the spacecraft plagued by technical problems. The canister containing the microscopic rock samples made a soft landing in Australia, the first time that samples from an asteroid had been brought back to Earth for study.
Now, the Japanese government has approved a follow-up mission, Hayabusa 2. This time the probe is scheduled to be launched in 2014 and rendezvous with the asteroid known as 1999 JU3 in mid-2018. Samples would again be taken and returned to Earth in late 2020…
See Universe Today for the full article.
Vesta, while one of the largest asteroids, is still a lot smaller than Earth, and yet it has a mountain that is three times taller than Mt. Everest, reaching about 22 kilometres (13 miles) in height. It sits inside the huge south polar crater, so is similar to many other craters on various planets and moons which have central peaks. It is surprising nonetheless to see such a large mountain on a relatively small body like Vesta, especially since it is so much higher than the tallest mountain on Earth!
The included image, taken by the orbiting Dawn spacecraft, shows a perspective view of the topography, but without the curvature of Vesta, as if you were looking at it standing on a flat Vesta instead of rounded. The resolution is about 300 metres (1,000 feet). The additional slideshow images show various views of the mountain. There is also a large steep-sloped scarp which bounds part of the south polar crater.
There will be a news conference on Wednesday, October 12 at 10:00 a.m. PDT to discuss the latest results from Dawn, to be held at the Annual Meeting of the Geological Society of America, in Minneapolis. It can be watched live on the Geological Society of America web site and on Ustream, which includes a moderated chat.
This article was first published on Examiner.com.