Dwarf Planet Ceres' Bright Spots Suggest an Ancient Ocean

[Judi Lynn]

By Nola Taylor Redd, Space.com Contributor | December 14, 2017 07:23am ET

NEW ORLEANS — The dwarf planet Ceres' famous bright spots suggest that the gray, crater-laden world is surprisingly active, a new study reports.

Ceres' bright patches may overlie pools of salty water, which could be the remnants of an ancient, subsurface ocean, study team members said.

"It's possible there is still brine coming up to the surface," lead author Nathan Stein, a planetary scientist at the California Institute of Technology in Pasadena, told Space.com. "It's certainly intriguing." [Awesome Ceres Photos by NASA's Dawn Spacecraft]

Stein and his team categorized the more than 300 bright patches on Ceres' surface into four groups, while planetary geologist Lynnae Quick, of the Smithsonian Institution in Washington, D.C., examined what could be driving the spots' differences. Along with Carol Raymond, the deputy principal investigator for NASA's Dawn mission, which has been orbiting Ceres since March 2015, the pair presented their results here at the American Geophysical Union meeting on Tuesday (Dec. 12).

More:
https://www.space.com/39094-dwarf-planet-ceres-bright-spots-geologic-activity.html?utm_source=notification

[muriel_volestrangler]

1. The Dawn scientists are now trying to get that spacecraft closer than ever to Ceres

In addition, as we have discussed in detail, Earth's ambassador to two giants in the main asteroid belt has had to contend with severe life-limiting problems. Dawn's reaction wheels have failed, and now it has consumed most of its original small supply of hydrazine that it uses in compensation. It has also expended most of the xenon propellant for its uniquely capable ion propulsion system. It was not clear that a truly productive future would be possible for this aged, damaged ship with some supplies that are so limited. Fortunately, Dawn has endless supplies of creativity, ingenuity, dedication and enthusiasm.

For several months, the flight team has been studying the feasibility of flying the spaceship closer to Ceres than had ever been seriously considered. Dawn spent more than eight months in 2015-2016 circling about 240 miles (385 kilometers) above the dwarf planet. It had spectacular views of mysterious landscapes and acquired a wealth of data far beyond what the team had anticipated. Then Dawn flew to a higher altitude during its first extended mission for new observations. Now engineers are making progress on ways to operate the spacecraft in an elliptical orbit that would allow it to swoop down to below 125 miles (200 kilometers) for a few minutes on each revolution. Their results so far are very encouraging. There are still many complex technical problems to solve, and months of additional work remain. Dawn can wait relatively patiently in its current orbit, where it expends hydrazine quite parsimoniously as it measures cosmic rays.

The promising potential for observing Ceres in elliptical orbits from closer than ever before makes a second extended mission there extremely attractive. NASA and the panel of scientists and engineers convened to provide an independent, objective assessment concluded that further exploration of Ceres would be the most valuable assignment for the spacecraft. It is noteworthy that Dawn is the only spacecraft ever to orbit two extraterrestrial destinations and even now, having significantly exceeded its original objectives, has the capability to leave Ceres and pay a brief visit to a third (although it does not have enough xenon left to orbit a third), but the prospects for new discoveries at Ceres are too great to pass up.

https://dawn.jpl.nasa.gov/mission/journal_10_31_17.html