posted 01-20-2015 10:19 PM               

NASA's Dawn to asteroids: questions, comments

This topic is for comments and questions in response to the updates under: NASA's Dawn mission to asteroids Vesta and Ceres.

Dawn is the ninth mission in NASA's Discovery Program. The probe will be the first to orbit two planetary bodies, asteroid Vesta and dwarf planet Ceres, during a single mission. Vesta and Ceres lie in the asteroid belt between Mars and Jupiter.

posted 01-20-2015 10:22 PM            

As NASA's Dawn spacecraft closes in on Ceres, new images show the dwarf planet at 27 pixels across, about three times better than the calibration images taken in early December.

posted 02-21-2015 10:10 AM            

Are images not being taken on at least a daily basis? Why does it take so long to release them? It seems like the public is being "drip-fed" a few images per week, in spite of the fact that entry into Ceres orbit is only about 2 weeks away. Why?

One of the most fascinating aspects of a new world, never seen in close-up before, literally opening up before our eyes, is the steady increase in resolution, day by day, as new pictures come in. Why are we being deprived of that experience?

posted 02-21-2015 10:18 AM               

The positions of the spacecraft and dwarf planet are already determined well enough with the conventional navigation methods that controllers know which particular stars are near Ceres from Dawn’s perspective. It is the analysis of precisely where Ceres appears relative to those stars that will yield the necessary navigational refinement. Later, when Dawn is so close that the colossus occupies most of the camera’s view, stars will no longer be visible in the pictures. Then the optical navigation will be based on determining the location of the spacecraft with respect to specific surface features that have been charted in previous images.

To execute an OpNav, Dawn suspends ion thrusting and turns to point its camera at Ceres. It usually spends one or two hours taking photos (and bonus measurements with its visible and infrared mapping spectrometer). Then it turns to point its main antenna to Earth and transmits its findings across the solar system to the Deep Space Network.

...Dawn turned to observe Vesta during that approach phase more often than it does on approach to Ceres, and the reason is simple. It has lost two of its four reaction wheels, devices used to help turn or stabilize the craft in the zero-gravity, frictionless conditions of spaceflight. (In full disclosure, the units aren’t actually lost. We know precisely where they are. But given that they stopped functioning, they might as well be elsewhere in the universe; they don’t do Dawn any good.)

posted 02-21-2015 01:22 PM               

"This mission isn't for people who want instant gratification," Rayman said.

posted 02-21-2015 04:30 PM            

This sequence of events clearly shows that the images are ALREADY "in the can" as Dawn is resuming its attitude for ion thrusting.

I would also like to think that a major NASA exploratory mission like Dawn can pre-book time on the DSN for a time-critical data transfer the timing of which must have been calculated weeks or months in advance.

posted 03-06-2015 08:09 AM               

Confirmation that Dawn is in orbit though, won't come until later. Mission managers tweeted at 8:45 a.m. EST:

Downlink has begun! We're analyzing the signal to confirm that the spacecraft is healthy and in orbit at Ceres.

posted 03-06-2015 08:44 AM               

Confirmed: I am in orbit around Ceres.

posted 03-06-2015 01:05 PM               

quote:

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Originally posted by p51:
...why of a sudden

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posted 05-14-2015 03:59 PM               

For anyone wanting/needing a more focused look at the spot, I cropped and resampled this image.

posted 03-10-2016 01:13 PM               

NASA/JPL Dawn Program Team to Receive 2015 Robert J. Collier Trophy

The National Aeronautic Association (NAA) announced last evening (March 9) at their Spring Awards Dinner that the NASA/JPL Dawn Program Team has been named as the recipient of the 2015 Robert J. Collier Trophy "in recognition of the extraordinary achievements of orbiting and exploring protoplanet Vesta and dwarf planet Ceres, and advancing the nation's technological capabilities in pioneering new frontiers in space travel."

The Collier Selection Committee, comprised of 32 individuals from throughout the aerospace industry, met earlier in the day to listen to presentations from nine nominees.

The Collier Trophy is awarded annually "...for the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space vehicles, the value of which has been thoroughly demonstrated by actual use during the preceding year." The list of Collier recipients represents a timeline of air and space achievements, marking major events in the history of flight.

"The Committee reviewed very strong nominations from throughout the aviation and space industry – commercial, military, general aviation, space, and even ballooning," said Jim Albaugh, Chairman of NAA. "Any one of them would have been a worthy Collier Trophy Recipient, and I want to congratulate our colleagues at NASA and JPL on their great accomplishment with the Dawn Program."

Other nominees for the 2015 Collier Trophy were:

• Airbus A350 XWB
  
• Blue Origin New Shepard Team
  
• C-5M Super Galaxy
  
• HA-420 HondaJet
  
• ICON A5
  
• New Horizons Project Team
  
• Two Eagles Balloon Team
  
• UCAS-D Autonomous Aerial Refueling Demonstration

Jonathan Gaffney, President and CEO of NAA, managed the selection process. "This was one of the strongest lists of Collier nominations NAA has seen in the past decade, and all who participated in the process can be very proud of their work. I particularly want to thank our Chairman and Selection Committee for all the time and effort they put into this most important and historic task."

The Collier Trophy will be formally presented at the Annual Robert J. Collier Trophy Dinner on June 9, 2016 at a location to be determined.

posted 09-02-2016 10:14 AM               

"When we got to Ceres, we were expecting to be surprised, and we have been in many ways," Dawn principal investigator Chris Russell, a professor of geophysics and space physics at the University of California, Los Angeles (UCLA), told Space.com.

"Ceres has been active during its history inside; the interior has been changing, evolving, much like the Earth's interior changes with time," added Russell, lead author of one of the new Science papers and co-author on the other five. "It's in the transition between the smaller asteroids and the Earth, in that it changes, and has changed, over the years from the time that the material initially came together."

posted 11-22-2016 04:20 PM               

In one image, Ceres' huge Occator Crater shows its central bright region, the brightest on Ceres. The crater itself is 57 miles wide (92 kilometers), and 2.5 miles deep (4 km). That makes it 77 times larger than the Barringer Crater in Arizona. Dawn took the picture when it was about 920 miles (1,480 km) above the surface, in early October.

Planetary scientists think the bright spots might be from briny material bubbling up during geologic activity; the liquid would sublimate away leaving the salts behind. Another asteroid slamming into Ceres could also cause upwelling, which is what some think happened at Occator Crater.

posted 11-07-2018 08:50 AM            

NASA's Dawn spacecraft has gone silent, ending a historic mission that studied time capsules from the solar system's earliest chapter.

posted 08-10-2020 04:55 PM               

On Monday, a suite of seven studies in the journal Nature scrutinize extended mission data from Dawn, peering at Ceres' dull, lifeless shell and finding definitive evidence that it is an ocean world.

"The new results confirm the presence of liquid inside Ceres," says Julie Castillo-Rogez, a planetary scientist at NASA's Jet Propulsion laboratory (JPL) and co-author across six new studies. The discovery of liquids hints that Ceres, the closest dwarf planet to Earth, may have been a habitable world and raises the possibility that these types of worlds may harbor life.