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

[1oldman2]

For an estimated delta_v of just 20 cm/s.

That seems an amazingly subtle dance Dawn is doing with Ceres gravity, Thanks for quantifying that.

 

[OmCheeto]

The kids at JPL were awarded their trophies on Thursday.

Dawn Mission Honored With Collier Trophy
NEWS | JUNE 10, 2016​

Really glad I became a pen pal with Dr. Rayman.
Really glad that Marcus got me hooked on this mission.

Smart people make good friends.

 

[OmCheeto]

Wait, what?

Will Dawn Visit a Third Object in the Asteroid Belt?
June 6, 2016
NASA is considering sending the Dawn spacecraft to a third asteroid after it finishes its mission at the dwarf planet Ceres.
...

hmmm... I haven't really been keeping up on the xenon supply... hmmmm...

 

[1oldman2]

Wait, what?
hmmm... I haven't really been keeping up on the xenon supply... hmmmm...

My thoughts too...

 

[OmCheeto]

How did I miss this news?

20 April 2016
NASA’s Dawn probe may visit third asteroid after Ceres and Vesta
...
This summer, Dawn’s Ceres mission will officially end. But earlier this week, principal investigator Chris Russell of the University of California at Los Angeles and his team sent a proposal to NASA for an extension.
...

Perhaps I'll extend my road trip this week, to include Pasadena. I think I need a face to face chat with Mr. Rayman...

 

[mfb]

That would be amazing.

It does make sense, if they have sufficient xenon. Ceres' shadow is approaching, so the current orbit doesn't allow continued operation for too long. I wouldn't expect that Dawn can shift the orbital plane fast enough to make that attractive, going to an eccentric orbit with even lower periapsis is discouraged by the goal to keep the orbit stable, and taking picture #20 of the same spot doesn't give as much science information as the first few pictures anyway.

 

[1oldman2]

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

June 14 - Dawn Stereo Mapping Proceeding Well

"Yesterday and today the spacecraft transmitted its latest Ceres data to Earth. Now it is taking
more stereo photos to reveal the three dimensional character of the alien landscapes. It is
also continuing to acquire neutron, gamma ray, visible and infrared spectra of Ceres."

Asteroids are getting a lot of attention lately.

 

[1oldman2]

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

"June 17 - Dawn To Complete Orbit Adjustment
Dawn has had another very productive week of operations, but it has still
more to do. Occasionally Dawn executes small maneuvers with its ion
engine to keep the orbit synchronized with the observation plans. These
orbit maintenance maneuvers (OMMs) are always performed in two
windows separated by eight or nine days. The first part of the latest OMM
was on June 9. Today the spacecraft will complete the OMM, this time with
two thrust segments. Starting about 4:00 PM, it will use its ion engine for a
little over an hour, and then it will thrust once more for 44 minutes starting
shortly after 1:00 AM tomorrow. The combined effect of all three thrust
segments is to change Dawn's velocity by about 0.8 mph (1.3 kilometers
per hour).

Following the OMM, the spacecraft will point its main antenna at Earth to
transmit more pictures and spectra. On June 19, it will resume observing
Ceres."

 

[1oldman2]

 

[1oldman2]

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

June 24 - Dawn Making More Ceres Measurements

The spacecraft transmitted a large volume of Ceres measurements on June
22-23 and now is collecting even more stereo photos and spectra of the dwarf
planet.

Dawn and Ceres orbit the sun together, independently of Earth. Shortly before
4:00 AM PDT today, the spacecraft was pi astronomical units from Earth, or
about 292 million miles (470 million kilometers). One astronomical unit is the
average distance between Earth and the sun.

 

[1oldman2]

I can't help but wonder what Marcus would have made of this.
http://www.nasa.gov/feature/jpl/recent-hydrothermal-activity-may-explain-ceres-brightest-area
Dawn is definitely giving us our moneys worth.

 

[OmCheeto]

I can't help but wonder what Marcus would have made of this.
http://www.nasa.gov/feature/jpl/recent-hydrothermal-activity-may-explain-ceres-brightest-area
Dawn is definitely giving us our moneys worth.

I would imagine, that he would have laughed that my only observation, was my new discovery, that the "soda", in "soda pop", was etymologically linked to "sodium carbonate".

 

[1oldman2]

http://www.nasa.gov/feature/jpl/dawn-completes-primary-mission
June 30 - Dawn Completes Prime Mission and Continues Observing Ceres

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

June 30 - Dawn Completes Prime Mission and Continues Observing Ceres

Today marks the official conclusion of Dawn's prime mission, which began when
the spacecraft left Earth on September 27, 2007. The mission has far surpassed
all of its objectives for exploring protoplanet Vesta and dwarf planet Ceres.
Some interesting statistics and other information on the prime mission are here.

Dawn transmitted a large volume of scientific data to Earth on June 27-28, and it
is continuing to observe Ceres even as the prime mission concludes. On July
1-2, it will transmit more pictures and spectra from its final mapping orbit at an
altitude of 240 miles (385 kilometers).

http://dawn.jpl.nasa.gov/news/news-detail.html?id=6553

 

[mfb]

I guess the recent spectroscopy data makes staying at Ceres more attractive, compared to the idea of going to a third object. But then they will have to do something about the orbit to stay out of the shadow.

 

[1oldman2]

I guess the recent spectroscopy data makes staying at Ceres more attractive, compared to the idea of going to a third object. But then they will have to do something about the orbit to stay out of the shadow.

I have read one of the main reasons for leaving Ceres orbit is there are rules in place concerning the contamination of other bodies by Earth organisms, thus they don't want Dawn crashing on Ceres. I'm just wondering why that wouldn't apply to a third body as well. In the case of the Juno spacecraft they plan on deorbiting and burning it up in the atmosphere of Jupiter to remove the chance of it contaminating Europa or other satellites of the Jovian system.

 

[mfb]

The nominal mission let's Dawn stay in its current orbit. Dawn doesn't go to a lower orbit partially for that reason: the current orbit is expected to be stable for decades, if we think we have to avoid a crash there is enough time to plan and launch a mission that captures Dawn and puts it in a higher orbit (or even completely away from Ceres).

 

[OmCheeto]

How did I miss this news?

Perhaps I'll extend my road trip this week, to include Pasadena. I think I need a face to face chat with Mr. Rayman...

I guess Marc was upset that I didn't come visit.

...NASA determined that the Dawn spacecraft should remain at the dwarf planet Ceres, rather than changing course to the main belt asteroid Adeona. [ref]​

Well, at least we know where they were planning on going.

 

[1oldman2]

Well, at least we know where they were planning on going.

I can't tell you how pleased I am with this decision!

 

[1oldman2]

July 6 - Dawn Exploring Ceres in Extended Mission
- from Chief Engineer/ Mission Director, Marc Rayman (JPL)
"NASA Headquarters approved an extension of Dawn's mission at Ceres,
taking advantage of the probe's capabilities to continue making discoveries
about the nature of this fascinating dwarf planet.

Dawn has been acquiring more stereo images and gathering additional
information with all of its spectrometers. The spacecraft began sending its
latest data to Earth early this morning, and it will continue until tomorrow
afternoon when it resumes its observations."

 

[1oldman2]

Dawn is full of surprises, this is very "cool".
http://dawn.jpl.nasa.gov/news/news-detail.html?id=6560
http://www.astronomy.com/news/2016/07/dawn-maps-ceres-craters-where-ice-can-accumulate

 

[OmCheeto]

Several new things to report:

1. I was kind of bummed out, thinking that Marc Rayman was no longer doing his monthly journal, as it's now two weeks late, and I didn't remember it ever being late, so I sent him an email this morning. He kindly replied with basically the same message included in today's status report:

2016
July 13 - Extended Mission Proceeding Flawlessly

Dawn is being very productive in its extended mission. It has been taking more stereo photographs (including some in color) as well as measuring spectra of Ceres in visible, infrared, gamma rays and neutrons. The spacecraft is healthy and continuing in its orbit 240 miles (385 kilometers) above the alien surface.

For readers who follow the Dawn Journal, there has been a delay for personal reasons, but don't worry: the Dawn Journals will resume soon and will continue as long as Dawn continues its ambitious and exciting mission of exploration. There is much more to look forward to!​

2. JPL has announced that they will have a live show tomorrow:

NASA Jet Propulsion Laboratory
1 hr ago
To Boldly Go! Join us for a live-streamed public talk about the voyages of the NASA Dawn Mission to Vesta and Ceres in the Asteroid Belt. http://ustream.tv/NASAJPL2
July 14, 2016
7 p.m. PT
10 p.m. ET
0200 UTC​

3. It appears that there was more than one reason for staying in orbit around Ceres:

“The long-term monitoring of Ceres, particularly as it gets closer to perihelion — the part of its orbit with the shortest distance to the sun — has the potential to provide more significant science discoveries than a flyby of Adeona,” Mr. Green said in a statement. [ref]​

I never thought of that.

per wiki

Aphelion_: 445,410,000 km
Perihelion: 382,620,000 km​

That seems like a pretty significant difference.

per Dawn Journal, January 31, 2016

Ceres, which takes 4.6 years (one Cerean year) for each loop, attained its aphelion, or greatest distance from the sun, on Jan. 6. On that day, it was 2.98 AU (277 million miles, or 445 million kilometers) from the gravitational master of the solar system.​

So perihelion should be around April of 2018.
That would be pretty awesome if they could extend the mission that long.
Though, I think that would be a stretch.
On the other hand...

“Less than a year ago, I would have thought it was ridiculous that the spacecraft would even be operating at this point,” lead Dawn engineer Marc Rayman told the New York Times.​

And here's something I didn't know, and I find somewhat mind boggling:

One famously extendable mission has been the Mars rover Opportunity. Its primary mission was only three months long, yet it’s lasted for more than 12 years. Opportunity got another extension this time around.​

Wow.

 

[1oldman2]

Fantastic post! thanks. I particularly appreciate the heads up in item #2, got to see that, and I likely would have missed it without your post.
I hadn't thought about the possible advantages of observing Ceres and the changes as it gets in closer, might just get to study some interesting sublimation process or who knows what, but I'm glad Dawn is sticking around for the show.
I do follow what Opportunity is up to and noticed the "extension", these announcements always make me smile, I see they are considering extending the Juno science orbits if the radiation doesn't fry it first, my fingers are crossed on that one. I'm a firm believer in milking these missions for all the data we can.

 

[1oldman2]

Hi Om, A while back in this thread I mentioned reading and looking at illustrations of Ceres as a kid, thought I would show you a cover shot of the book in question.
(note the price)

 

[1oldman2]

Almost forgot !

 

[mfb]

Opportunity and all similar expensive missions get extended as long as the devices are working somewhat - would be a waste to shut them down. A rover that lasts for 50 times its design lifetime is still exceptional, of course.

 

[1oldman2]

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

July 20 - Dawn Performing More Investigations of Ceres

"Since completing its last transmission of data on July 18, Dawn has been collecting
more data with all of its scientific instruments as it circles dwarf planet Ceres every 5.4
hours. It will send more data to Earth on July 21 and 22.

Dawn has been in orbit around Ceres for more than 500 days. During that time, it has
revealed complex and fascinating landscapes and provided scientists with a wealth of
information on the alien world."

 

[1oldman2]

And something new to ponder. http://www.nasa.gov/feature/jpl/the-case-of-the-missing-ceres-craters

 

[OmCheeto]

The new journal is out!

DAWN JOURNAL
July 27, 2016​

Still no hint as to a time frame for the end of the mission.
I wonder if the craft can operate just with the two remaining reaction wheels, as it sounds like the hydrazine is running low.
hmmm... If so, it could go on, for decades.

 

[1oldman2]

If so, it could go on, for decades.

Thats what mfb mentions in post #977, would be interesting.
From marc,
"the orbit will remain relatively stable for much longer than that,
perhaps even millennia. The ship will not make landfall."

 

[mfb]

It won't have xenon fuel forever, at some point it will enter the shadow of Ceres unless they find some very clever orbit that precesses at the right rate - similar to sun-synchronous orbits on Earth. And that is assuming the two reaction wheels continue working - but even then, they are not sufficient for three-axis control, so some hydrazine will be spent.