Dwarf planet's mysterious bright spots create mini-atmosphere, say scientists

The perplexing bright spots on Ceres, a dwarf planet in our solar system's asteroid belt, seem to be creating a localized atmosphere at the bottom of a crater.

|
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The brightest spots on dwarf planet Ceres are seen in this image taken by NASA's Dawn spacecraft on June 6, 2015.
|
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.
A 3-mile-high (5 kilometers) mountain dubbed "The Pyramid" juts from Ceres' limb in this photo by NASA's Dawn spacecraft.

The investigation into the dwarf planet Ceres' mysterious bright spots has taken an intriguing new twist.

The famous bright spots at the bottom of Ceres' Occator crater appear to be sublimating material into space, creating a localized atmosphere within the walls of the 57-mile-wide (92 kilometers) hole in the ground, new observations by NASA's Dawn spacecraft suggest.

"If you look at a glancing angle, you can see what seems to be haze, and it comes back in a regular pattern," Dawn principal investigator Christopher Russell, of UCLA, said during a presentation Tuesday (July 21) at the second annual NASA Exploration Science Forum, which took place at the agency's Ames Research Center in Moffett Field, California. [Photos of Ceres, Queen of the Asteroid Belt]

The bright spots "are possibly subliming, or they're providing some atmosphere in this particular region of Ceres," Russell said. The haze covers about half of Occator crater and does not extend beyond the hole's rim, he added.

This new information would seem to bolster the argument of people who think Ceres' bright spots are composed of ice, rather than some sort of salt. (Those are the two leading possible explanations at the moment.)

"This is our major mystery," Russell said, referring to the nature of the bright spots.

During the talk, Russell revealed some other discoveries by Dawn. For example, the probe's observations show that Ceres is slighly smaller than researchers had thought — about 598 miles (962 km) in diameter, rather than 607 miles (974 km). That means the dwarf planet is about 4 percent denser than previously thought, Russell said.

Dawn has also spotted numerous long, linear features whose cause is unknown, as well as one big mountain that mission team members have dubbed "The Pyramid." This massif, which is about 3 miles (5 km) tall and 19 miles (30 km) wide, features a flat top and strangely streaked flanks, Russell said.

"It's got white sides on much of the surface," he said. "It just looks like the material is cascading down from above."

Overall, Dawn's observations are showing Ceres to be a relatively active world rather than an inert chunk of rock and ice, mission team members say.

"Some areas are less densely cratered than others, suggesting that there are geological processes that erase the craters," Dawn chief engineer and mission director Marc Rayman, of NASA's Jet Propulsion Laboratory in Pasadena, California, wrote in a blog post last month. "Indeed, some regions look as if something has flowed over them, as if perhaps there was mud or slush on the surface."

Scientists know from Ceres' density that the dwarf planet contains lots of water, the majority of which is almost certainly in the form of ice. But some researchers think liquid water may exist in places beneath Ceres' surface — intriguing because here on Earth, life thrives pretty much wherever liquid water pools or flows.

"It is possible that the water systems associated with Ceres may harbor life, and could be conducive to life more than some of the outer solar system bodies," Russell said. "So I would say, we really do need to spend some time in probing the surface of Ceres and checking out its astrobiological implications." 

The $466 million Dawn mission launched in September 2007, tasked with studying the two largest objects in the asteroid belt — Ceres and the 330-mile-wide (530 km) Vesta. Dawn orbited Vesta from July 2011 through September 2012, and the spacecraft arrived at Ceres this past March. 

Dawn is currently spiraling down to its third science orbit of Ceres, after experiencing engine problems that delayed the trek for more than two weeks. The spacecraft will reach this orbit, which lies about 900 miles (1,450 km) above Ceres' surface, in mid-August. (Dawn is equipped with ion engines, which are extremely efficient but generate low levels of thrust, so such orbital maneuvers take time.)

The probe will get closer still in January. Dawn's fourth and final science orbit lies at an altitude of just 235 miles (375 km). The probe will continue studying Ceres from that orbit until the end of its mission, in June 2016.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @SpacedotcomFacebook or Google+. Originally published on Space.com.

Copyright 2015 SPACE.com, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Follow CSMonitor's board Astronomy on Pinterest.
You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to Dwarf planet's mysterious bright spots create mini-atmosphere, say scientists
Read this article in
https://www.csmonitor.com/Science/2015/0730/Dwarf-planet-s-mysterious-bright-spots-create-mini-atmosphere-say-scientists
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe