NASA's Dawn mission to the asteroids

[Rick]

NASA Spacecraft Becomes First to Orbit a Dwarf Planet

NASA's Dawn spacecraft has become the first mission to achieve orbit around a dwarf planet. The spacecraft was approximately 38,000 miles (61,000 kilometers) from Ceres when it was captured by the dwarf planet's gravity at about 4:39 a.m. PST (7:39 a.m. EST) Friday.

Mission controllers at NASA's Jet Propulsion Laboratory in Pasadena, California received a signal from the spacecraft at 5:36 a.m. PST (8:36 a.m. EST) that Dawn was healthy and thrusting with its ion engine, the indicator Dawn had entered orbit as planned.

"Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet," said Marc Rayman, Dawn chief engineer and mission director at JPL. "Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres, home."

More: http://www.jpl.nasa.gov/news/news.php?feature=4503

[Rick]

Dawn's complex approach to Ceres

Since its discovery in 1801, Ceres has been known as a planet, then as an asteroid, and later as a dwarf planet. Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls it “home.”

Earth’s robotic emissary arrived at about 4:39 a.m. PST today. It will remain in residence at the alien world for the rest of its operational life, and long, long after.

Before we delve into this unprecedented milestone in the exploration of space, let’s recall that even before reaching orbit, Dawn started taking pictures of its new home. Last month we presented the updated schedule for photography. Each activity to acquire images (as well as visible spectra and infrared spectra) has executed smoothly and provided us with exciting and tantalizing new perspectives.

While there are countless questions about Ceres, the most popular now seems to be what the bright spots are. It is impossible not to be mesmerized by what appear to be glowing beacons, shining out across the cosmic seas from the uncharted lands ahead. But the answer hasn’t changed: we don’t know. There are many intriguing speculations, but we need more data, and Dawn will take photos and myriad other measurements as it spirals closer and closer during the year. For now, we simply know too little.

More: http://dawnblog.jpl.nasa.gov/2015/03/06/dawn-journal-march-6/

[Rick]

Other Asteroids Contributed Elusive Olivine to Vesta

Olivine should be one of the most abundant minerals on asteroid Vesta, but it remains elusive. Scientists working on NASA’s Dawn mission to Vesta were initially thrilled to find few scattered remains of this enigmatic mineral as evidence for telltale signs of planetary differentiation. However, a new paper in the journal Icarus says that at least some of this olivine might not have come from Vesta, but instead was delivered by other asteroids.
 
“Olivine provides important constraints on how small protoplanets like Vesta form and what we can learn about the formation of terrestrial planets, including Earth, but what we see on Vesta might not be the smoking gun we were looking for,” said Planetary Science Institute researcher Lucille Le Corre, the lead author of the new study.

More: http://www.psi.edu/news/olivinevesta

[Rick]

Getting Down to Science at Ceres

 Dawn's assignment when it embarked on its extraordinary extraterrestrial expedition in 2007 can be described quite simply: explore the two most massive uncharted worlds in the inner solar system. It conducted a spectacular mission at Vesta, orbiting the giant protoplanet for 14 months in 2011-2012, providing a wonderfully rich and detailed view. Now the sophisticated probe is performing its first intensive investigation of dwarf planet Ceres. Dawn is slowly circling the alien world of rock and ice, far from Earth and far from the sun, executing its complex operations with the prowess it has demonstrated throughout its ambitious journey.

Following an interplanetary trek of 7.5 years and 3.1 billion miles (4.9 billion kilometers), Earth's ambassador arrived in orbit on March 6, answering Ceres' two-century-old celestial invitation. With its advanced ion propulsion system and ace piloting skills, it has maneuvered extensively in orbit. Traveling mostly high over the night side of Ceres, arcing and banking, thrusting and coasting, accelerating and decelerating, climbing and diving, the spaceship flew to its first targeted orbital altitude, which it reached on April 23.

More: http://www.jpl.nasa.gov/blog/2015/4/getting-down-to-science-at-ceres

[Rick]

Ceres Animation Showcases Bright Spots

The mysterious bright spots on the dwarf planet Ceres are better resolved in a new sequence of images taken by NASA's Dawn spacecraft on May 3 and 4, 2015. The images were taken from a distance of 8,400 miles (13,600 kilometers). The animation is available at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=pia19547

In this closest-yet view, the brightest spots within a crater in the northern hemisphere are revealed to be composed of many smaller spots. However, their exact nature remains unknown.

"Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," said Christopher Russell, principal investigator for the Dawn mission from the University of California, Los Angeles.

More: http://www.jpl.nasa.gov/news/news.php?feature=4582

[Rick]

Ceres Bright Spots Seen Closer Than Ever

NASA's Dawn mission captured a sequence of images, taken for navigation purposes, of dwarf planet Ceres on May 16, 2015. The image showcases the group of the brightest spots on Ceres, which continue to mystify scientists. It was taken from a distance of 4,500 miles (7,200 kilometers) and has a resolution of 2,250 feet (700 meters) per pixel.

"Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," Christopher Russell, principal investigator for the Dawn mission from the University of California, Los Angeles, said recently.

More: http://www.jpl.nasa.gov/news/news.php?feature=4594

[Rick]

Dawn Spirals Closer to Ceres, Returns a New View

A new view of Ceres, taken by NASA's Dawn spacecraft on May 23, shows finer detail is becoming visible on the dwarf planet. The spacecraft snapped the image at a distance of 3,200 miles (5,100 kilometers) with a resolution of 1,600 feet (480 meters) per pixel. The image is part of a sequence taken for navigational purposes.

Go see it at: http://www.jpl.nasa.gov/news/news.php?feature=4605

[Rick]

Dawn Journal | May 28, 2015

The first intensive mapping campaign was extremely productive. As the spacecraft circled 8,400 miles (13,600 kilometers) above the alien terrain, one orbit around Ceres took 15 days. During its single revolution, the probe observed its new home on five occasions from April 24 to May 8. When Dawn was flying over the night side (still high enough that it was in sunlight even when the ground below was in darkness), it looked first at the illuminated crescent of the southern hemisphere and later at the northern hemisphere.

When Dawn traveled over the sunlit side, it watched the northern hemisphere, then the equatorial regions, and finally the southern hemisphere as Ceres rotated beneath it each time. One Cerean day, the time it takes the globe to turn once on its axis, is about nine hours, much shorter than the time needed for the spacecraft to loop around its orbit. So it was almost as if Dawn hovered in place, moving only slightly as it peered down, and its instruments could record all of the sights as they paraded by.

More: http://dawnblog.jpl.nasa.gov/2015/05/28/dawn-journal-may-28-2015/

[Apophis]

Look at http://www.jpl.nasa.gov/spaceimages/images/largesize/PIA19559_hires.jpg

If you look at the crater with the white in and go up 2 large craters then 11 o,clock to next large crater it seems to have features in it formed with flowing liquid.

roger

(Edit: Image issues -- Rick)

[Rick]

Bright Spots Shine in Newest Dawn Ceres Images

New images of dwarf planet Ceres, taken by NASA's Dawn spacecraft, show the cratered surface of this mysterious world in sharper detail than ever before. These are among the first snapshots from Dawn's second mapping orbit, which is 2,700 miles (4,400 kilometers) above Ceres.

The region with the brightest spots is in a crater about 55 miles (90 kilometers) across. The spots consist of many individual bright points of differing sizes, with a central cluster. So far, scientists have found no obvious explanation for their observed locations or brightness levels.

"The bright spots in this configuration make Ceres unique from anything we've seen before in the solar system. The science team is working to understand their source. Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt. With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon," said Chris Russell, principal investigator for the Dawn mission based at the University of California, Los Angeles.

More: http://www.jpl.nasa.gov/news/news.php?feature=4619

[Mike]

It's interesting that in EVERY picture the spots are super bright white. If it was reflection off liquid I would expect it to be bright only at certain angles. This now make me think it is salts or somethings crystalline that has many facets that will always face the spacecraft.

[Rick]

Ceres Spots Continue to Mystify in Latest Dawn Images

Dawn has been studying the dwarf planet in detail from its second mapping orbit, which is 2,700 miles (4,400 kilometers) above Ceres. A new view of its intriguing bright spots, located in a crater about 55 miles (90 kilometers) across, shows even more small spots in the crater than were previously visible.

At least eight spots can be seen next to the largest bright area, which scientists think is approximately 6 miles (9 kilometers) wide. A highly reflective material is responsible for these spots -- ice and salt are leading possibilities, but scientists are considering other options, too.

More: http://www.jpl.nasa.gov/news/news.php?feature=4633

[Rick]

Dawn Journal | June 29

Dawn is continuing to unveil a Ceres of mysteries at the first dwarf planet discovered. The spacecraft has been extremely productive, returning a wealth of photographs and other scientific measurements to reveal the nature of this exotic alien world of rock and ice. First glimpsed more than 200 years ago as a dot of light among the stars, Ceres is the only dwarf planet between the sun and Neptune.

Dawn has been orbiting Ceres every 3.1 days at an altitude of 2,700 miles (4,400 kilometers). As described last month, the probe aimed its powerful sensors at the strange landscape throughout each long, slow passage over the side of Ceres facing the sun. Meanwhile, Ceres turned on its axis every nine hours, presenting itself to the ambassador from Earth. On the half of each revolution when Dawn was above ground that was cloaked in the darkness of night, it pointed its main antenna to that planet far, far away and radioed its precious findings to eager Earthlings (although the results will be available for others throughout the cosmos as well). Dawn began this second mapping campaign (also known as “survey orbit”) on June 5, and tomorrow it will complete its eighth and final revolution.

The spacecraft made most of its observations by looking straight down at the terrain directly beneath it. During portions of its first, second and fourth orbits, however, Dawn peered at the limb of Ceres against the endless black of space, seeing the sights from a different perspective to gain a better sense of the lay of the land.

Read on...

[Mike]

Here you go, I said it was salts..

Pluto may be the star of the dwarf planet scene for the next few days, but let's not forget about Ceres: We've been salivating over the mysterious white spots on its surface since NASA's Dawn orbiter sent its first photos home. But according to the mission's principle investigator, the crowd favorite theory -- that the spots are made of some kind of water or ice -- is probably about to be debunked.

http://www.washingtonpost.com/news/speaking-of-science/wp/2015/07/10/the-weird-white-spots-on-ceres-might-not-be-ice-after-all

[Rick]

Dawn Maneuvering to Third Science Orbit

NASA's Dawn spacecraft is using its ion propulsion system to descend to its third mapping orbit at Ceres, and all systems are operating well. The spiral maneuvering over the next five weeks will take the spacecraft to an altitude of about 900 miles (less than 1,500 kilometers) above the dwarf planet.

The spacecraft experienced a discrepancy in its expected orientation on June 30, triggering a safe mode. Engineers traced this anomaly to the mechanical gimbal system that swivels ion engine #3 to help control the spacecraft's orientation during ion-thrusting. Dawn has three ion engines and uses only one at a time.

More: http://www.jpl.nasa.gov/news/news.php?feature=4659