Dawn Mission

[PPI Brian]

The Dawn spacecraft has made her Mars flyby for a gravity assist. She fired her ion engine again and she is now on her way to asteroid Vesta.

Here's a video narrated by Leonard Nimoy:
http://video.google.com/googleplayer.swf?docid=-5412000236766165719&hl=en&fs=true
http://video.google.com/videoplay?docid=-5412000236766165719&hl=en

Here's a link to the Dawn homepage:
http://dawn.jpl.nasa.gov/multimedia/videos.asp

[PPI Brian]

Dawn is cruising toward her first target -- asteroid Vesta. Can't wait to see the pictures.  

http://www.youtube.com/v/IjR36EAR_B4


http://www.youtube.com/v/kAftZFlqZtM

[PPI Brian]

Here's an interesting video of the launch of the Dawn probe on September 27, 2007. Our members build, assemble and launch these vehicles. I really like the purging liquid oxygen before the launch; it reminds me of a race horse waiting to bolt from the gate on a cold day. Notice the solid rocket motors that weren't lit during lift off? Those are the three air start motors that help the space craft reach escape velocity. The Delta II was never designed to carry payloads this heavy, and would not be able to deliver a payload of this mass without the additional boosters. I don't know about you, but I never get tired of watching rocket launches.  

http://www.youtube.com/v/a7fcrZOcg5g

[PPI Brian]

Prepare to be dazzled. Dawn is on final approach to asteroid Vesta. She will ease into orbit on July 16th and spend the next 12 months exploring this fascinating proto planet. I am anxiously awaiting the first clear pictures of Vesta. No clear images of Vesta have ever been captured, so we don't know what to expect. Here's the last log from Dawn's principal engineer:

Dawn Journal

June 23, 2011

Dear Dawnstinations,

Vesta beckons, and Dawn responds. Now more than halfway through its approach to Vesta, Dawn continues creeping up on the destination it has been pursuing since it began its interplanetary travels. The separation between them gradually shrinks as the probe's ion thrusting brings its orbit around the sun into a closer and closer match with Vesta's. At the same time, the giant protoplanet's gravity tugs gently on the approaching ship, luring it into orbit.

Starting at the beginning of the approach phase on May 3, Dawn interrupted thrusting once a week to photograph Vesta against the background stars. These images help navigators determine exactly where the probe is relative to its target. This technique does not replace other means of navigation but rather supplements them. One of the principal methods of establishing the spacecraft's trajectory relies on accurately timing how long it takes radio signals, traveling, as all readers know, at the universal limit of the speed of light, to make the round trip between Earth and Dawn. Another uses the Doppler shift of the radio waves, or the slight change in pitch caused by the craft's motion. These sensitive measurements remain essential to navigating the faraway ship as it sails the interplanetary seas.

Despite the very slow approach, the distance is small enough now that observing Vesta weekly is no longer sufficient. To achieve the navigational accuracy required to reach the intended orbit in early August, last week the frequency of imaging was increased to twice per week. In each session, half of the pictures are taken with long exposures to ensure many stars are detectable, thus overexposing the much brighter disc of the nearby Vesta. The other half use short exposures to ensure that the rocky world shows up correctly so its precise location can be measured. The visible and infrared mapping spectrometer has been commanded to observe Vesta during three of these sessions, each time providing valuable information that will help scientists select instrument settings for when Dawn is close enough to begin its detailed scientific measurements.

In addition to the regular campaign of imaging for navigation, mission controllers have other plans in store for the approach phase that were laid out more than a year ago. Twice in the next few weeks, the spacecraft will watch Vesta throughout its complete 5.3-hour rotation on its axis, revealing exciting new perspectives on this uncharted body. The explorer also will search for moons of the alien world.

There are several ways you can have the same spectacular views as Dawn while it closes in on this immense protoplanet. You could build your own ion-propelled interplanetary spaceship and travel to Vesta. Just imagine how exciting that would be! But if you did that, the time to write all the logs describing your adventure probably would make the undertaking impractical. Another option would be to build your own telescope. To see Vesta as clearly as Dawn sees it today, you would need a telescope only three times the size of the Hubble Space Telescope. Regrettably, then you would have to wait until Earth's and Vesta?s orbits around the sun brought them into closer alignment. In the meantime, Dawn?s camera would draw much closer to its subject. By the beginning of August, it will see Vesta with more than 100 times the clarity that Hubble could ever obtain. Still another alternative would be to go here to see some of the best views that humankind's robotic ambassador to the asteroid belt has returned. New pictures will be added regularly.

A relic that bears witness to the dawn of the solar system, a colossus that outweighs all other residents of the main asteroid belt save Ceres (Dawn's second destination), a fuzzy point of light among the stars that has intrigued and enticed astronomers for more than two centuries, a mysterious orb that has stirred the passions of creatures on a distant planet, inspiring them to dispatch an emissary to scrutinize it, is finally being revealed as a unique and fascinating world. Dawn's images delight and tantalize us, and the wait for still better views now is brief indeed.

After more than 950 days of ion thrusting, with an effective change in velocity of more than 6.6 kilometers per second (15,600 mph), Dawn's orbit is so much like Vesta's that their paths around the sun are quite similar. Less than a month ago, they were coming together at 240 meters per second (540 mph). Today, the relative speed has declined to only 110 meters per second (250 mph). By July 16, Dawn will be traveling no faster toward Vesta than you can drive in a car. The probe will be close enough and slow enough that the protoplanet's gravity will tenderly take the approaching explorer in its grasp. The next log will be posted shortly after Dawn is in a high, loose orbit around Vesta, still spiraling down toward survey orbit, where it will begin making detailed studies of its home for the subsequent year.

Dawn is 152 thousand kilometers (95 thousand miles) from Vesta, or 40 percent of the average distance between Earth and the moon. It is also 1.39 AU (208 million kilometers or 129 million miles) from Earth, or 515 times as far as the moon and 1.37 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take 23 minutes to make the round trip.


Dr. Marc D. Rayman
10:00 pm PDT June 23, 2011

[PPI Karl]

I can't wait to see.  Very exciting.

[PPI Karl]

"After traveling through the the solar system for nearly four years, NASA's Dawn spacecraft is poised to arrive in orbit around Vesta, a huge asteroid the size of Arizona.  The historic event is set to take place at about 10 p.m. PDT Friday, July 15 (1 a.m. EDT July 16), NASA officials said."

And here she is.  (Ain't she sweet?!)

NASA's Dawn spacecraft snapped this photo of the huge asteroid Vesta on July 9, 2011.
It was taken from a distance of about 26,000 miles (41,000 kilometers) away from Vesta.
CREDIT: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

[PPI Tim]

Looks like a big coco puff

[PPI Tracy]

Mmmmmm......cocoa puffs.....

[PPI Brian]

At long last we have our first close up views of Vesta. This huge geologic feature was known from Hubble images of Vesta, but the images were so blurry and indistinct that planetary scientists thought it must be a central peak from a massive impact crater. Instead it appears to be a mountain. Very curious indeed. 

[PPI Karl]

Amazing!  How weird is that?!  Considering the processes needed to have built a mountain, does this imply that Vesta was once geologically active?  Or, that it was part of a larger geologically active planet?  (Maybe Vesta and Ceres are the remnants of two different planets in the same orbit.  They're very different materials.  Okay.  Down, Karl.  My imagination is overacting so much it could win a daytime Emmy.  )

On a related tangent:  have you seen the latest news about the VLT's observations of Haumea?  The dwarf planet and its two moons are 100% covered in crystalline ice?  Bizarre.

[PPI Brian]

Hi Karl,

Yes I read about the VLT observation of Haumea. Strange that this little world seems to have a debris field around it. It would be great to get some close up images of these outer worlds, wouldn't it?

JPL released the following information today. Vesta is a strange and beautiful little world.

http://www.youtube.com/v/jHp9w8N0mcw

[PPI Karl]

We must be visiting the same websites.  I just saw this same video this morning, and was blown away.  There's also something awe inspiring about an asteroid being large enough to have a "night side."  Too cool.

[PPI Brian]

Vesta continues to be a fascinating place. Here's a news release from last week that I meant to share earlier.  

New View of Vesta Mountain from NASA's Dawn Mission

October 11, 2011 - PASADENA, Calif. -- A new image from NASA?s Dawn spacecraft shows a mountain three times as high as Mt. Everest, amidst the topography in the south polar region of the giant asteroid Vesta.

The peak of Vesta?s south pole mountain, seen in the center of the image, rises about 13 miles (22 kilometers) above the average height of the surrounding terrain.  Another impressive structure is a large scarp, a cliff with a steep slope, on the right side of this image. The scarp bounds part of the south polar depression, and the Dawn team?s scientists believe features around its base are probably the result of landslides.

The image is online at http://www.nasa.gov/mission_pages/dawn/multimedia/pia14869.html. It was created from a shape model of Vesta, and shows an oblique perspective view of the topography of the south polar region. The image resolution is about 300 meters per pixel, and the vertical scale is 1.5 times that of the horizontal scale.

Dawn entered orbit around Vesta in July. Members of the mission team will discuss what the spacecraft has seen so far during a news conference at the Annual Meeting of the Geological Society of America in Minneapolis. Among other things, they?ll share their hypotheses on the origins of Vesta?s curious craters.

The meeting, at the Minneapolis Convention Center, runs from Oct. 9 to 12, with the Dawn news conference scheduled for Wednesday, Oct. 12, at 10 a.m. PDT (noon CDT).

[PPI Brian]

This video is a composite from a series of images provided by the framing camera on NASA's Dawn spacecraft. You can see a full rotation of Vesta, which occurs over the course of roughly five hours.

I'm amazed by the quality of these images. 

http://www.youtube.com/v/ElJv4HnFIqI