Dawn dead in Ceres orbit, ran out of fuel Oct 2018

[marcus]

Salutations back, Om!
I hope it was OK giving those samples. One was an overview and the other dealt with GRaND. The third was just an afterthought, that "session 801", kind of a random sample. All too technical but I didn't see anything that was less. The press briefing video you linked us to was great, thanks again!
==Rayman==
March 25 - Dawn Making New Observations

Dawn is operating flawlessly as it acquires more photos and spectra of Ceres. The explorer transmitted its findings to Earth on March 23-24, and it will send the data it is collecting now on March 27-28.
==endquote==
Looks like a 4 day cycle---wonderful it's been going smoothly so far.

 

[marcus]

sample image, posted recently. Makes the streaks of ejecta really clear
You may have to press "reply" to see the image. I'll put in both jpg and tif

http://photojournal.jpl.nasa.gov/jpeg/PIA20409.jpg

Here's the tif, may have to click "reply" to see it. Not sure it is any sharper. More at:
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA20409
"This view from NASA's Dawn spacecraft shows a moderate-sized impact feature that is imprinted upon the southern rim of Mondamin Crater. Shadows created by the low angle of solar illumination in this scene make visible rays of ejected material that spread radially outward from the crater. Boulders of various sizes can be seen around the crater's rim and on the sunlit part of its floor..."
http://dawn.jpl.nasa.gov/multimedia/images/ceres.html
http://photojournal.jpl.nasa.gov/tiff/PIA20409.tif

 

[marcus]

==Rayman==

March 29 - As Dawn continues its exploration of Ceres, the operations team is conducting its regular evaluation of the spacecraft 's orbit around the dwarf planet. The probe has been doing an excellent job collecting data, but small deviations from the planned orbit gradually accumulate. Occasionally the ion engine is used to perform an "orbit maintenance maneuver," as explained in the (February Dawn Journal.)The team will decide this week whether to adjust the orbit.

Today is the 209th anniversary of the discovery of Vesta. When Heinrich Wilhelm Matthäus Olbers first spotted it, he could hardly have imagined that a ship from Earth would travel to that mysterious point of light among the stars. And yet Dawn did, and it provided a detailed and richly rewarding exploration of the world that Olbers found.
==endquote==

Dawn Journal for March should be appearing soon:
http://dawn.jpl.nasa.gov/mission/journal.asp

 

[1oldman2]

==Rayman==
Today is the 209th anniversary of the discovery of Vesta. When Heinrich Wilhelm Matthäus Olbers first spotted it, he could hardly have imagined that a ship from Earth would travel to that mysterious point of light among the stars. And yet Dawn did, and it provided a detailed and richly rewarding exploration of the world that Olbers found.
==endquote==

Dawn Journal for March should be appearing soon:
http://dawn.jpl.nasa.gov/mission/journal.asp

Thanks for the Vesta link, I had never seen that info, very interesting about the meteorite material.

 

[marcus]

Image 56 is of a "sinuous canyon". It looks deep cut and meandering. What could have made this?
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA20551

 

[1oldman2]

Image 56 is of a "sinuous canyon". It looks deep cut and meandering. What could have made this?
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA20551

If that was a satellite view of a location on Earth and you subtracted the cratering I would definitely say it resembled a river bed just based on the erosion patterns you see in the bends. That being an obvious long shot, I would say possibly a fracture zone related to internal stress or large impact.
I have been zooming in and studying a lot of these images but haven't done that with this one yet, I would be interested to see more of the area surrounding this canyon.

 

[1oldman2]

This is kind of a test to see what the image would look like when uploaded. I choose this enlargement to demonstrate both the "river bend" and fracture/scarp effect visible at the same time. not sure what would cause this effect.

 

[OmCheeto]

...
Dawn Journal for March should be appearing soon:
http://dawn.jpl.nasa.gov/mission/journal.asp

It's out!

Dawn Journal | March 31 [2016]
by Marc Rayman

 

[1oldman2]

It's out!

 

[OmCheeto]

Emily Lakdawalla had some interesting things to say about the conference last week:

LPSC 2016: So. Much. Ceres.
2016/03/30 23:31 UTC
...
All in all, three days of Ceres was a lot to swallow, and it's taken me another three days to try to absorb it all and summarize the presentations in this post. We'll continue to drown in data from Dawn for as much as another year, and then the mission will be over. I fully expect it to take decades for scientists to get everything that they can out of this rich data set.

I would say something nice about Marc's new journal, but it appears he's sent me a lethal personal challenge;

(We won’t delve into the reason here. But for fellow nerds, it has to do with the alignment of the axes of the operable reaction wheels with the plane in which Dawn rotates to keep its instruments pointed at Ceres and its solar arrays pointed at the sun. The hydrazine saving depends on the wheels’ ability to store angular momentum and applies only in hybrid control, not in pure hydrazine control. Have fun figuring out the details. We did!)

I'm pretty sure I'd pop about a thousand blood vessels in my brain if I tried to figure that out.

 

[OmCheeto]

Image 56 is of a "sinuous canyon". It looks deep cut and meandering. What could have made this?
http://dawn.jpl.nasa.gov/multimedia/images/image-detail.html?id=PIA20551
...

Had you not mentioned it being a "canyon", I would have guessed it was a crater wall. I spent a couple of hours trying to find contextual imagery, but was unsuccessful.

 

[marcus]

===Rayman===

April 1 - Dawn to Adjust Orbit

At the end of another productive week, Dawn is transmitting its most recent scientific data to the Deep Space Network . The March Dawn Journal presents some of the mission's latest findings about Ceres.

The spacecraft will start executing an orbit maintenance maneuver (OMM) shortly after 5:00 PM PDT today. It will thrust with its ion engine for a little more than two hours, and then about 1:00 AM PDT on April 2 will begin thrusting again for the same duration. Following that, Dawn will resume its observations of Ceres. The second half of the OMM will consist of two more thrust segments on April 9-10. (OMMs are explained in more detail in the February Dawn Journal.)
==endquote==
March Journal is lengthy and informative:
http://dawnblog.jpl.nasa.gov/2016/03/31/dawn-journal-march-31-3/

==more on Occator==
Scientists are still working on refining their understanding of this striking region. As we described in December, it seems that following the powerful impact that excavated Occator Crater, underground briny water reached the surface. The detailed photographs show many fractures cutting across the bright areas, and perhaps they provided a conduit. Water, whether as liquid or ice, would not last long there in the cold vacuum, eventually subliming. When the water molecules disperse, either escaping from Ceres into space or falling back to settle elsewhere, the dissolved salts are left behind. This reflective residue covers the ground, making the spellbinding and beautiful display Dawn now reveals.

While the crater is estimated to be a geological youngster at 80 million years old, that is an extremely long time for the material to remain so reflective. Exposed for so long to cosmic radiation and pelting from the rain of debris from space, it should have darkened. Scientists don’t know (yet) what physical process are responsible, but perhaps it was replenished long after the crater itself formed, with more water, carrying dissolved salts, finding its way to the surface. As their analyses of the photos and spectra continue, scientists will gain a clearer picture and be able to answer this and other questions.
...
...
==endquote==
Nice picture of the central bright spot---similar to the image Om posted earlier.

 

[marcus]

Also a bit of news about GRaND:
=== http://dawnblog.jpl.nasa.gov/2016/03/31/dawn-journal-march-31-3/ ===
We saw that extensive measurements of the faint nuclear radiation can help identify the atomic constituents. While the analysis of the data is complicated, and much more needs to be done, a picture is beginning to emerge from Dawn’s neutron spectrometer (part of the gamma ray and neutron detector, GRaND). These subatomic particles are emitted from the nuclei of atoms buried within about a yard (meter) of the surface. Some manage to penetrate the material above them and fly into space, and the helpful ones then meet their fate upon hitting GRaND in orbit above. (Most others, however, will continue to fly through interplanetary space, decaying into a trio of other subatomic particles in less than an hour.) Before it escapes from the ground, a neutron’s energy (and, equivalently, its speed) is strongly affected by any encounters with the nuclei of hydrogen atoms (although other atomic interactions can change the energy too). Therefore, the neutron energies can indicate to scientists the abundance of hydrogen. Among the most common forms in which hydrogen is found is water (composed of two hydrogen atoms and one oxygen atom), which can occur as ice or tied up in hydrated minerals.

GRaND shows Ceres is rich in hydrogen. Moreover, it detects more neutrons in an important energy range near the equator than near the poles, likely indicating there is more hydrogen, and hence more (frozen) water, in the ground at the high latitudes. Although Ceres is farther from the sun than Earth, and you would not consider it balmy there, it still receives some warmth. Just as at Earth, the sun’s heating is less effective closer to the poles than at low latitudes, so this distribution of ice in the ground may reflect the temperature differences. Where it is warmer, ice close to the surface would have sublimed more quickly, thus depleting the inventory compared to the cooler ground far to the north or south.
==endquote==

 

[marcus]

==Rayman==

April 5 - Dawn Healthy and Operating Well

Since thrusting with its ion engine on April 1 and 2 to refine its orbit around Ceres, Dawn has been collecting more data on the dwarf planet. It is taking pictures, measuring the gravity field, and collecting infrared, gamma ray and neutron spectra. Shortly after 9:30 AM PDT today, the spacecraft will turn its sensors away from Ceres to point its 5-foot (1.5-meter) antenna to Earth. It will resume its scientific observations by 1:30 PM tomorrow.

==endquote==

 

[marcus]

==Rayman==

April 8 - Dawn to Execute Small Maneuver This Weekend

Dawn is continuing to observe Ceres. Tomorrow it will begin the second half of the orbit maintenance maneuver it performed on April 1 and 2. It will thrust with ion engine #2 for almost two hours starting about 3:30 PM and then again for almost 2.5 hours beginning shortly before 11:00 PM.

After it completes the maneuvering on April 10, the spacecraft will use its main antenna to establish contact with the Deep Space Network and transmit all the data it collected since the last communications session on April 6.

==endquote==

 

[OmCheeto]

Mission Status Update
- from Chief Engineer/ Mission Director, Marc Rayman (JPL)
2016
April 11 - Dawn Beginning New Ceres Mapping

Dawn is taking pictures and collecting spectra of Ceres. It is now pointing its camera and other instruments slightly ahead and to the left as it circles the dwarf planet. With pictures taken at an angle, scientists will have stereo views so they can construct a more detailed topographical map than they developed in the third mapping orbit. (The March Dawn Journal and the links there explain the stereo imaging in more detail.)

On April 9-10, Dawn maneuvered with its ion engine to synchronize its orbit with the plan for observing Ceres. (These orbit maintenance maneuvers are described in the February Dawn Journal.) Then on April 10-11, it pointed its main antenna to Earth to radio its latest observations to the planet where its journey began.

Dawn's main computer is using software controllers installed five years ago this week,shortly before the spacecraft arrived at Vesta. And exactly two years earlier, they also loaded new software. (Follow the link to find out how you can get a copy of the software for your own use, or simply put your computer or smartphone in the main asteroid belt, send us the coordinates, and we'll install it for you.)

I checked the links, and couldn't find the software he was talking about. I guess I'll have to launch my laptop into outer space.

 

[OmCheeto]

JPL has released 4 new images:

New Ceres Images Show Bright Craters
...
"Little Oxo may be poised to make a big contribution to understanding the upper crust of Ceres," said Chris Russell, principal investigator of the mission, based at the University of California, Los Angeles.

And they explained why some of the craters aren't round:

The [Haulani] crater's polygonal nature (meaning it resembles a shape made of straight lines) is noteworthy because most craters seen on other planetary bodies, including Earth, are nearly circular. The straight edges of some Cerean craters, including Haulani, result from pre-existing stress patterns and faults beneath the surface.

3 of the images are accessible from the above link. The fourth image is here: Dada and Roskva Craters

Latest status updates:
2016

April 18 - Dawn Gathering More Ceres Data

Dawn remains healthy in its lowest orbit around Ceres, 240 miles (385 kilometers) above the alien surface. It is taking new pictures and gathering other data as it circles Ceres every 5.4 hours. Tomorrow morning the spacecraft will begin sending all these measurements to Earth, and the next day it will start collecting even more data.
​

April 15 - Mapping Progressing Well

After filling its memory with more observations of Ceres, Dawn began transmitting its results to Earth yesterday afternoon. Tonight it will resume studying the dwarf planet.​

 

[1oldman2]

JPL has released 4 new images:

Very nice! I particularly liked the color enhanced Haulani shot.

 

[1oldman2]

In honor of Marcus, I would like with PF's approval to keep this thread open throughout the Dawn mission. While it would be difficult if not impossible to match Marcus's presentation I would hope that the followers of his thread will post updates and discoveries as they become available.
And so along those lines here is the latest update from JPL's Marc Rayman,
"May 6 - Dawn Performing Well
Dawn is completing another productive week of Ceres observations, taking pictures for topography and collecting spectra for the atomic and mineralogical composition. It will send more data to Earth on May 7-8. While pointing its camera and spectrometers at Earth, the spacecraft broadcasts a radio signal through an auxiliary antenna. That signal is used for precise tracking of Dawn's orbital motion to map the variations in Ceres' gravitational field, which provides insight into the interior structure of the dwarf planet. (All these methods of learning about Ceres have been described in recent Dawn Journals.)"

RIP, Marcus

 

[1oldman2]

- from Chief Engineer/ Mission Director, Marc Rayman (JPL)
2016
"May 9 - Dawn's Fourth Mapping Orbit Continues
After beaming its latest Ceres measurements to NASA's Deep Space Network on May 7-8, Dawn is now making still more.
One year ago today, Dawn completed its first mapping orbit around Ceres at an altitude of 8,400 miles (13,600 kilometers) and began spiraling lower.
A single revolution at that altitude required 15 days. Now in its fourth mapping orbit,
Dawn's altitude is 240 miles (385 kilometers), and its pictures are 35 times sharper.
Held tighter in Ceres' gravitational grip, Dawn travels four times faster at this lower altitude,
and a single orbital loop now takes less than 5.5 hours."

The stereo imaging that's being done currently should make a very interesting view of Ceres, I'm looking forward to it's completion.

 

[1oldman2]

- from Chief Engineer/ Mission Director, Marc Rayman (JPL)
2016
May 13 - Another Lucky Day for Dawn

"On this Friday the 13th, Dawn is maintaining its long streak of good
luck (supplemented with some skill) in exploring Ceres. The spacecraft
began transmitting its most recent pictures and spectra to Earth
yesterday and will finish late this morning. It will resume observing the
dwarf planet around noon".

I'll keep an eye out for the latest images,hope to post some soon.

 

[1oldman2]

I'll keep an eye out for the latest images,hope to post some soon.

 

[1oldman2]

And last but not least

 

[mfb]

That double crater in the last picture looks weird. The craters don't overlap, they look as if they were created at the same time. Impact from split up object?

 

[mheslep]

Or, less likely, some kind of strong rigid material dividing the craters that resisted impact. That the craters are approximately the same age favors the simultaneous impact theory.

 

[1oldman2]

Here is a zoom view.

 

[1oldman2]

Or, less likely, some kind of strong rigid material dividing the craters that resisted impact. That the craters are approximately the same age favors the simultaneous impact theory.

They do resemble clones of one another, I'm going to see if there are any comments from JPL on this feature, I honestly hadn't focused on it until mfb mentioned it. The center ridge does seem to have a darker material. I suspect both of you may be correct, if I find anything out I'll mention it in a post.

 

[1oldman2]

A couple of other features that have me curious, the material on the crater rim in the top left corner of the first image, and on the flanks of AH in the second image there seems to be significant amounts of the "bright white material". I have thought of that stuff as being a deeper subsurface trait so it strikes me as out of place so high up the slopes (and that thing is relatively very high). I still haven't heard a theory on the formation of AH and wonder if that could be a clue.

 

[1oldman2]

DISCLAIMER!... I'm not sure if this is an appropriate place for humor but while searching images I came across this and thought "what the heck, a good laugh never hurts"

 

[Dotini]

DISCLAIMER!... I'm not sure if this is an appropriate place for humor but while searching images I came across this and thought "what the heck, a good laugh never hurts"
View attachment 100785

Have we seen these anomalous blobs somewhere before in this long thread? Maybe so, but I'm good with writing them off as photo defects.

 

[OmCheeto]

Have we seen these anomalous blobs somewhere before in this long thread? Maybe so, but I'm good with writing them off as photo defects.

It was you, almost a year ago, who first pointed them out.

May 18 2015

Below are two stills from the animation. What are these artifacts in the images?
...

And you-know-who made a joke about them.

I'm guessing dust on the camera lens.
The donut shaped anomaly can be seen in two other frames.
...
The only other explanation: Aliens.

 

[Dotini]

Continuing on the subject of amusing lights, shadows, and patterns which show up at ~450'/ pixel:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA19979

 

[1oldman2]

They do resemble clones of one another, I'm going to see if there are any comments from JPL on this feature, I honestly hadn't focused on it until mfb mentioned it. The center ridge does seem to have a darker material. I suspect both of you may be correct, if I find anything out I'll mention it in a post.

This image from Ceres shows a small, double-impact crater (at bottom) near a larger
crater. The larger structure has a crater floor with roughly the same crater density, and
therefore roughly the same age, as the material outside the crater rim. Within the large
crater is a small impact scar with rays of bright material.

NASA's Dawn spacecraft took this image on March 23, 2016, in its low-altitude mapping
orbit, at a distance of about 240 miles (385 kilometers) above the surface. The image
resolution is 120 feet (35 meters) per pixel.

regarding post # 938

 

[1oldman2]

from Chief Engineer/ Mission Director, Marc Rayman (JPL)

"May 16 - Dawn Operating Smoothly

Dawn is devoting most of today and tomorrow to sending more Ceres data to Earth.
Every three weeks, the flight team evaluates Dawn's orbit to determine whether a
small adjustment maneuver with the ion engine is needed. (These "orbit
maintenance maneuvers" were described in the February Dawn Journal.) Today the
team concluded that the orbit is so good that no maneuver is necessary."

"May 19 - Dawn Executing All Planned Observations

Dawn is hard at work observing Ceres and storing the data in computer memory.
The spacecraft is programmed to pause its measurements early on May 21, when it
will turn to point its main antenna to Earth and radio the data to JPL.

Dawn is continuing to operate in "hybrid control," using its two operable reaction
wheels in combination with hydrazine to control its orientation. Mission controllers
activated the two reaction wheels in December when the probe reached this low
altitude orbit. As long as they operate, the two wheels allow the dwindling supply of
hydrazine to be used very efficiently."

Hopefully more imaging to post soon.

 

[1oldman2]

Hopefully more imaging to post soon.