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

[marcus]

As of 20h UT (noon pacific) the current status view shows Dawn taking pictures of Ceres.
this time the side of the cube with the large high-gain antenna is pointing at the planet.
if the simulated view is realistic down to that level of detail, it must mean the "navcam" they're using is located on that same side of the box.

Anyway it is a slightly different orientation from what I recall the last couple of times they took pictures.
the main distinction is the view shows the thruster off (no blue-green plasma trail) and the main axis with the solar panel "wings" vertical rather than nearly horizontal. When they finish picture-taking and communicating back with Earth the simulated view will presumably show the craft rotated back and the thrust back on.
http://neo.jpl.nasa.gov/orbits/fullview2.jpg

 

[lpetrich]

I note the speed: 182 mph relative to Ceres -- nearly 300 km/h. The top speeds of many high-speed trains are typically 300 km/h, and sometimes a little bit more. These are the fastest land vehicles in regular service. Fast by familiar standards, but snail-paced by space-travel standards.

 

[marcus]

I note the speed: 182 mph relative to Ceres -- nearly 300 km/h. The top speeds of many high-speed trains are typically 300 km/h, and sometimes a little bit more. These are the fastest land vehicles in regular service. Fast by familiar standards, but snail-paced by space-travel standards.

Yesterday it was 184 mph. They are obviously working to slow Dawn down between now and the beginning of March, when capture should occur.
So that is part of what the thrust should accomplish. Without that, probe would be accelerating as it gets closer to Ceres and capture would not happen.

So as we watch the speed change over the next couple of weeks, we are hoping/expecting it to slow down.

 

[marcus]

Of course from our usual solar system point of view, motion relative to the sun, the probe is going 17.32 kilometers per second
http://neo.jpl.nasa.gov/orbits/fullview1.jpg

It's only relative to Ceres that the approach must be gradual, and must slow down over the next couple of weeks.

You may remember that the earlier approach trajectory (before events in September necessitated redesigning it) would have had the probe coming in much more slowly, at this point. And there would have been no overshoot. It would have settled into circular orbit over a month earlier, because it would have slowed down more completely before now.

In either case the capture date is about the same, 5 or 6 March. Since we've turned a page, I'll bring forward the labeled diagram that Om made.

 

[marcus]

I just saw Canberra start talking with Dawn
https://eyes.nasa.gov/dsn/dsn.html
When I looked, it was quiet, as if standing by at ready (or during a pause) at 2:18 PM local time (20 Feb) and then at 2:19 PM it became active.

the antenna is one of the big ones, #43. It now seems to be on continuously.
It is in daylight, Madrid would seem to be the next one to take over, three or four hours from now, if it's a long session.

 

[OmCheeto]

I just saw Canberra start talking with Dawn
https://eyes.nasa.gov/dsn/dsn.html
When I looked, it was quiet, as if standing by at ready (or during a pause) at 2:18 PM local time (20 Feb) and then at 2:19 PM it became active.

the antenna is one of the big ones, #43. It now seems to be on continuously.
It is in daylight, Madrid would seem to be the next one to take over, three or four hours from now, if it's a long session.

A few minutes ago, I watched the Madrid dish #63 come online, switch on the carrier signal, receive some data, and then shut off. It all took about 20 minutes.
It was about 4:50 - 5:10 UTC, Feb 20.

I sure they post a picture from today. It's almost twice as close as the image posted two days ago. 46 kkm vs 83 kkm.

 

[marcus]

Thanks for the heads up, it is about time for them to switch. I went and looked and saw Canberra still engaged with Dawn, and Madrid was standing by (assigned to Dawn but quiet).
I hope you are right about them posting a picture. Here's that table of planned photoshoots:

Jan 13  (383,000) 27  (36) 0.83 95% OpNav 1
Jan 25  (237,000) 43  (22) 1.3 96% OpNav 2
Feb 3   (146,000) 70  (14) 2.2 97% OpNav 3
Feb 12  (83,000) 121  (7.8) 3.8 98% RC1
Feb 19  (46,000) 221  (4.3) 7.0 87% RC2
Feb 25  (40,000) 253  (3.7) 8.0 44% OpNav 4
Mar 1   (49,000) 207  (4.6) 6.5 22% OpNav 5
Apr 10  (33,000) 304  (3.1) 9.6 18% OpNav 6
Apr 15  (22,000) 455  (2.1) 14 50% OpNav 7

http://dawnblog.jpl.nasa.gov/2015/01/29/dawn-journal-january-29/[/B

EDIT: just went back at 10:16 pacific and they had switched.
https://eyes.nasa.gov/dsn/dsn.html
it was 5:16 PM at Canberra and their antenna was off the job
It was 7:16 AM in Madrid and their antenna was working with Dawn.
I think you are right about a picture.

 

[marcus]

Goldstone antenna #14 is still receiving from Dawn. Transmission will presumably conclude sometime this afternoon (it is noon pacific time at the moment).
Then Dawn can get back to thrusting, to slow itself down wrt. Ceres
I see that the speed relative to Ceres has crept up from 182 to 185 just during this photoshoot session.
Prior to 19 Feb it had been coming down: 184...183...182... I'll switch to metric equivalents.
At the start of the shoot, on 19 Feb, when thrust was turned off, current status gave it equal to 81.4 m/s
and now at noon 20 Feb, with transmission not yet complete, it is equal to 82.7 m/s.
I'm noting that for the planned capture the speed re Ceres has to get down to around 45 m/s
and unless the craft is thrusting it will naturally tend to increase as approach continues.
So these long photo shoot sessions have a price.
https://eyes.nasa.gov/dsn/dsn.html
http://neo.jpl.nasa.gov/orbits/fullview2.jpg

 

[OmCheeto]

...
So these long photo shoot sessions have a price.
...

I wish you hadn't said that.

Marc Rayman says:
February 19, 2015 at 11:20 pm
Hi Matt,

Image releases will occur only on normal NASA/JPL work days, which do not include weekends.
...
Dawn is budgeted for single shift operations.
...

As a former 24/7 hospital worker, and 24/7 submariner, I found it somewhat depressing to find out that the Dawn mission is run on "banker's hours".

So I took a picture, of my log, again...

Sorry I didn't have time before shift end, to fix the image.

But check that out! In the upper left hand corner, is the track of a meteorite, streaking through the atmosphere.

 

[marcus]

Now Goldstone has stopped. 3 pm pacific, 23h UT, no antenna is working with Dawn.
It could be turned around and thrusting now, to slow down its arrival.
http://neo.jpl.nasa.gov/orbits/fullview2.jpg
But the current status update as of 23h UT on 20 Feb does not show as having resumed normal operation yet.

You may have discovered a creative use for old shredded magazines, newspapers, and computer manuals, namely to make asteroids out of them. My wife disagrees with me on this. She says it is not an asteroid but simply an ordinary log for the fireplace. The multicolored shredded debris around it just gives it a realistic look, she says. That is the natural lichen which often grows on logs in the woods.

 

[OmCheeto]

Now Goldstone has stopped. 3 pm pacific, 23h UT, no antenna is working with Dawn.
It could be turned around and thrusting now, to slow down its arrival.
http://neo.jpl.nasa.gov/orbits/fullview2.jpg
But the current status update as of 23h UT on 20 Feb does not show as having resumed normal operation yet.

You may have discovered a creative use for old shredded magazines, newspapers, and computer manuals, namely to make asteroids out of them. My wife disagrees with me on this. She says it is not an asteroid but simply an ordinary log for the fireplace. The multicolored shredded debris around it just gives it a realistic look, she says. That is the natural lichen which often grows on logs in the woods.

I do believe that we are in some sort of cosmic synchronization period. I bought a shedder a couple of weeks ago and have been cursing myself for not listening to that "Dental Floss" guy, regarding saving old bank statements. I'm only finished back through 1999. My multicolored shredded debris has been joining the siblings of Ceres/Log in the fireplace, daily. Ugh. The only consolation is that kids, in the future, will have no clue what that reference is about. Thank god for "paperless".

Anyways, it's currently 4:02 UTC, the last image of Dawn was at 5:29 UTC, and the ion engine will be still off.

Never noticed before that they posted the images early.

Also, the minimum distance is only a couple of days away, according to lpetrich's numbers, so I wouldn't worry about too much speeding up.

Date      dist    speed    esc v
20-Feb    42.5    79.05    54.51
21-Feb    40.1    79.41    56.07
22-Feb    38.7    78.75    57.09
23-Feb    38.1    77.44    57.57
24-Feb    38.2    74.44    57.44
25-Feb    39.3    71.36    56.67
26-Feb    41.0    69.68    55.49
27-Feb    43.1    68.45    54.10
28-Feb    45.5    64.25    52.69
 1-Mar    47.9    60.73    51.32
 2-Mar    50.4    58.68    49.98
 3-Mar    53.4    55.29    48.65
 4-Mar    56.1    50.19    47.45
 5-Mar    58.5    46.97    46.42
 6-Mar    61.0    44.36    45.47
 7-Mar    63.4    40.50    44.67

 

[marcus]

Good point about closest approach on this pass coming up around 24 Feb. And anyway current status showed thrust was resumed an hour or so ago at 11PM pacific 20 Feb (or 7h UT 21 Feb) so all's apparently back to normal.

Now that Dawn is trailing Ceres somewhat, the planet is showing a phase. We can locate the sun and the orientation of the solar panels is making better sense in the simulated view.

 

[mfb]

Dawn is flying in a right angle relative to the Dawn/Ceres direction, so speed should not change much based on gravity (but velocity does - the acceleration from Ceres exceeds the acceleration from the ion engines if my calculations are not too far off). Still at 185 mph = 83m/s.

 

[marcus]

Good estimate! A little slower now that it is later in the day.
Current status as of 4 PM pacific on 21 Feb( that is 0h UT 22 Feb) says range 40.07 kkm and speed about 82 m/s (183 mph)
2 arcsin(475 / 40 070) = 1.36 deg
272% moon size. Appearing just a bit more gibbous than a half moon. Dawn passing nearly astern of the planet--give it a day or two more and Ceres should resemble a half moon.

Dawn's line of sight, trailing behind Ceres, should then make a right angle with the Sun-Ceres line.

 

[marcus]

Current status as of noon pacific 22 Feb ( 20h UT)
In the simulated view you see a "half moon" shape, almost. So Dawn is almost at right angles to the Ceres-Sun line
The blue-green ion tail is in the direction it is going, past Ceres and astern of it. It is thrusting to slow down.
Range is 39.02 kkm and speed is 80.5 m/s.

Simulated views in the online current status section are not always accurate. Sometimes the spacecraft attitude is wrong, sometimes the solar panels are not facing the sun when the thruster is on (and they would need full-face)
But right now it is beautifully accurate. You can see the tail goes in the right direction and the panels face the sun.

279% of moon-size right now. about as large as it will look for next month or so, since the distance to
Ceres will start growing in a day or two as Dawn overshoots and sails on past Ceres outwards (from sun)

 

[marcus]

To have it handy I'll bring forward a table derived from L. Petrich's numbers slightly modified so as to orient Z forwards in Ceres orbit plane.

X Y Z are coordinates relative to Ceres, which is (0,0,0), measured in kkm---thousands of km.
X is directed out from sun, in Ceres orbit plane
Y is directed perpendicularly up off the orbit plane, in Ceres' north pole direction
Z is directed forwards in Ceres orbit plane, the direction Ceres is moving, a negative shows the probe trailing behind.
Scroll the table down to get to the last row. It extends to 5 April and I may add some more days later.

date      X          Y          Z        distance from Ceres
F17   -45.9972    6.4086    -27.2882    53.86             
F18   -38.555    9.71627    -28.2185    48.75
F19   -32.3324    12.4392    -29.202    45.30             
F20   -26.169    14.8491    -29.9728    42.46
F21   -19.6171    17.2648    -30.4689    40.14
F22   -13.2794    19.4975    -30.6993    38.71
F23   -6.73346    21.6416    -30.593    38.07
F24   -0.502056    23.4431    -30.212    38.24
F25     5.62894    25.0851    -29.7158    39.29
F26     11.407    26.4613    -29.1488    40.98
F27     17.2899    27.6663    -28.1919    43.11
F28     22.8583    28.5286    -27.0313    45.46
M1      27.9985    29.1842    -25.6846    47.90
M2      32.8862    29.7513    -24.1873    50.51
M3      37.6439    30.1647    -22.7166    53.31
M4      41.9734    30.4246    -21.3167    56.05
M5      45.8274    30.5605    -19.8726    58.55
M6      49.5028    30.6491    -18.2955    61.02
M7      52.8252    30.4896    -16.7451    63.24
M8      55.7681    30.3242    -15.1946    65.27
M9      58.5427    30.0761    -13.6441    67.21
M10     58.5427    30.0761    -13.6441    67.21
M11     63.2886    29.4796    -10.5963    70.61
M12     65.1256    29.1961    -9.32939    71.97
M13     66.8636    28.8417    -7.90296    73.24
M14     68.4790    28.2510    -6.38793    74.35
M15     69.7223    27.7726    -4.80202    75.20
M16     70.7383    27.1819    -3.57051    75.86
M17     71.5002    26.8275    -2.34785    76.40
M18     72.0023    26.5440    -1.37327    76.75
M19     72.3581    26.2900    -0.12403    76.98
M20     72.4098    25.8411     1.05432    76.88
M21     72.2873    25.4277     2.33013    76.66
M22     72.0303    25.0319     3.22497    76.32
M23     71.7734    24.5653     4.24385    75.97
M24     71.1281    23.9983     5.08554    75.23
M25     70.1580    23.3604     6.02468    74.18
M26     68.9840    22.7402     6.74232    72.94
M27     67.6521    22.1023     7.46883    71.56
M28     66.0440    21.553       8.08901    69.94
M29     64.1702    20.9978     8.57630    68.06
M30     61.9597    20.5548     9.23193    65.92
M31     59.6842    20.2240     9.60404    63.74
A01      57.1311    20.0527     9.85212    61.34
A02      54.4022    19.8283    9.81668    58.72
A03      51.2408    19.6570    9.97616    55.78
A04      48.0025    19.6393    9.84326    52.79
A05      44.5782    19.8637    9.69264    49.75

 

[OmCheeto]

Has anyone else blown up the image of Ceres on the JPL "where is Dawn now" page

compared it to my log, and noticed

a weird similarity?

Disregarding the fact that they know how to use Photoshop, and I'm really bad with MacDoodlePaint.

Or should I not mention this, as it might get people thinking I'm in a conspiracy with the government, and this entire space mission was filmed from the back of my truck?

 

[OmCheeto]

On a somewhat "conspiracy" related side-note, Svetlana shows off the log from the back of her truck.

ESA Rosetta Mission ‏@ESA_Rosetta 11h11 hours ago
Happy birthday Svetlana Gerasimenko, co-discoverer of #67P! (Image: DLR (CC-BY 3.0), http://ow.ly/JupqF)

 

[marcus]

This just posted, is it RC2? Is this from the recent shoot, 19 Feb, or the earlier RC1? It doesn't say AFAICS.

I guess it is from the earlier shoot on 12 or 13 Feb, but sharper print for some reason. In any case the RC2 pictures should be online soon.

 

[marcus]

Today is one of the planned optical navigation photoshoots.

Jan 13  (383,000) 27  (36) 0.83 95% OpNav 1
Jan 25  (237,000) 43  (22) 1.3 96% OpNav 2
Feb 3   (146,000) 70  (14) 2.2 97% OpNav 3
Feb 12  (83,000) 121  (7.8) 3.8 98% RC1
Feb 19  (46,000) 221  (4.3) 7.0 87% RC2
Feb 25  (40,000) 253  (3.7) 8.0 44% OpNav 4
Mar 1   (49,000) 207  (4.6) 6.5 22% OpNav 5
Apr 10  (33,000) 304  (3.1) 9.6 18% OpNav 6
Apr 15  (22,000) 455  (2.1) 14 50% OpNav 7

http://dawnblog.jpl.nasa.gov/2015/01/29/dawn-journal-january-29/[/B
I just checked the current status view and it showed the probe with thrust off, oriented for picture-taking:
http://neo.jpl.nasa.gov/orbits/fullview2.jpg
Presumably we should see an antenna receiving data later today at DSN
https://eyes.nasa.gov/dsn/dsn.html

 

[OmCheeto]

This just posted, is it RC2? Is this from the recent shoot, 19 Feb, or the earlier RC1? It doesn't say AFAICS.
View attachment 79561

I guess it is from the earlier shoot on 12 or 13 Feb, but sharper print for some reason. In any case the RC2 pictures should be online soon.

I spent half an hour comparing the original RC1 image to this one. The only thing I could conclude was that I had low definition eyes. But I think you are right. I also think it's from RC1.

OMG! OMG! The new Journal is out! The new Journal is out!​

Dawn Journal | February 25
by Marc Rayman

Dear Fine and Dawndy Readers,

Feb 19th 2015, RC2​

 

[Dotini]

Ceres seems to have no shortage of polygonal craters.

 

[OmCheeto]

Personally, I like the pictographic message the Cerians have sent us:

"Einstein was wrong.
God does play dice, and he rolled a 5.
Though, his dice appear to be round.
We haven't yet figured out how that's possible.
But welcome, Earthlings!
Perhaps, together, we can figure this out."​

 

[Dotini]

http://www.nbcnews.com/science/space/dawn-probe-spots-bright-surprise-ceres-it-ice-n312831

NASA / JPL-CALTECH / UCLA / MPS / DLR / IDA
15 hours

Edit: More photos and comment from Emily.
http://www.planetary.org/blogs/emily-lakdawalla/2015/02251857-ceres-geology.html

 

[OmCheeto]

http://www.nbcnews.com/science/space/dawn-probe-spots-bright-surprise-ceres-it-ice-n312831

NASA / JPL-CALTECH / UCLA / MPS / DLR / IDA
15 hours

Edit: More photos and comment from Emily.
http://www.planetary.org/blogs/emily-lakdawalla/2015/02251857-ceres-geology.html

That's no dwarf planet...

ps. Don't blame me for this one. Blame NASA.
NASA's Dawn Mission retweeted the above.

 

[marcus]

Om, who is shooting a death ray at whom? btw humor aside do you like the term "dwarf planet"?
As I understand the definitions, if something is massive enough to pull itself into a roundish ball shape (rather than an irregular chunk shape like asteroids and comets) then it is officially either a PLANET or a DWARF-PLANET
and what makes the difference is whether it has been massive enough to sweep clear and control its orbit pathway.

I don't like the terminology. It sounds unkind. It lacks a feeling of affection. Here are some alternatives that don't give the unfortunate impression that there is something wrong about a planet that hasn't cleared the debris out of its path.

1. Miniplanet
2. Planette
3. Planikin
4. Orblet
5. Planetino

Which of these would you like best? What alternative name SHOULD they have given the category.

 

[marcus]

For the next ten days the critical thing to watch is the meters-per-second speed of the probe. In order to achieve capture by 6 March it has to get its speed down to around 46 m/s ---then it will actually be bound in orbit rather than just a "fly-by" visitor.
From today (26 Feb) to 6 March, as its distance increases from 41 to 61 kkm, the speed should decrease roughly as Petrich calculated. I've adapted his numbers

X Y Z are coordinates relative to Ceres, which is (0,0,0), measured in kkm---thousands of km.
X is directed out from sun, in Ceres orbit plane
Y is directed perpendicularly up off the orbit plane, approximately in Ceres' north pole direction
Z is directed forwards in Ceres orbit plane, the direction Ceres is moving, a negative shows the probe trailing behind.
distance from Ceres continues increasing for a while because the probe has some excess momentum
v_escape is the escape velocity at that given distance
v_probe is the predicted velocity the probe will actually have that day. It must fall below v_esc to achieve capture.

date      X          Y          Z        distance  v_esc  v_probe
F17   -45.9972    6.4086    -27.2882    53.86           
F18   -38.555    9.71627    -28.2185    48.75
F19   -32.3324    12.4392    -29.202    45.30           
F20   -26.169    14.8491    -29.9728    42.46
F21   -19.6171    17.2648    -30.4689    40.14
F22   -13.2794    19.4975    -30.6993    38.71
F23   -6.73346    21.6416    -30.593    38.07
F24   -0.502056    23.4431    -30.212    38.24
F25     5.62894    25.0851    -29.7158    39.29    56.67    71.36
F26     11.407    26.4613    -29.1488    40.98    55.48      69.67
F27     17.2899    27.6663    -28.1919    43.11    54.10     68.44
F28     22.8583    28.5286    -27.0313    45.46    52.68    64.25
M1      27.9985    29.1842    -25.6846    47.90    51.32     60.73
M2      32.8862    29.7513    -24.1873    50.51    49.98     58.67
M3      37.6439    30.1647    -22.7166    53.31    48.65     55.28
M4      41.9734    30.4246    -21.3167    56.05    47.44     50.18
M5      45.8274    30.5605    -19.8726    58.55    46.42     46.96
M6      49.5028    30.6491    -18.2955    61.02    45.47     44.35
M7      52.8252    30.4896    -16.7451    63.24    44.66     40.49
M8      55.7681    30.3242    -15.1946    65.27    43.97     37.71
M9      58.5427    30.0761    -13.6441    67.21
M10     58.5427    30.0761    -13.6441    67.21
M11     63.2886    29.4796    -10.5963    70.61
M12     65.1256    29.1961    -9.32939    71.97

The table starts 17 Feb and it shows the probe overshooting Ceres in the X direction (it has not had time to slow its X motion and will need Ceres gravity to pull it back in line)
likewise it shows the probe overshooting in the upwards Y direction.
Ceres' orbit inclination is 10 degrees and it just recently passed its descending node, so it is sloping down relative to the ecliptic (solar system plane) and to Dawn's prior orbit.
This gives Dawn some unwanted Speed in the "up" or Y direction. Again Ceres gravity will help draw the probe in.

 

[OmCheeto]

Om, who is shooting a death ray at whom? btw humor aside do you like the term "dwarf planet"?

No!

As I understand the definitions, if something is massive enough to pull itself into a roundish ball shape (rather than an irregular chunk shape like asteroids and comets) then it is officially either a PLANET or a DWARF-PLANET
and what makes the difference is whether it has been massive enough to sweep clear and control its orbit pathway.

I don't like the terminology. It sounds unkind. It lacks a feeling of affection. Here are some alternatives that don't give the unfortunate impression that there is something wrong about a planet that hasn't cleared the debris out of its path.

1. Miniplanet
2. Planette
3. Planikin
4. Orblet
5. Planetino

Which of these would you like best? What alternative name SHOULD they have given the category.

Hadn't really thought about it before.
From your list, Planetino is the best, IMHO.

Though, I would have probably come up with "Hobbit planet", myself.

 

[OmCheeto]

ps. Emily tweeted this, this morning:

Emily Lakdawalla @elakdawalla · 3h3 hours ago
ICYMI: @NASA_Dawn's latest Ceres pics finally resolve it as a geological world:​

I didn't really understand what she was trying to say. Are there geoillogical worlds?

 

[marcus]

How about planetino versus planetello?

I'm thinking of 200 or 300 years hence when some DNA-engineering has enabled people to live healthy lives in soft gravity, like the planetello Ceres gravity of 3% Earth normal gee. And somebody says "My sister and her husband got jobs on that icy planetello just beyond Mars."
"They like living in the planetello's caverns, they're learning springboard ballet and muscle-powered flight."

I suspect it's not unlikely they'd just wind up calling it a "planet" (even though astronomer's conventions limit the use of that term) or calling it a "world". If people live on a solar system orb why not use the general term and call it a world?

Om, there's the old question "how high could you jump?" Using the radius 475 km and the mass 943 billion billion kg, I calculated the surface gravity as 1/35 of our 9.8 ms^-2. Around 0.28 m/s².

Is it as simple as saying that you could jump 35 times as high?

BTW just checked current status and it said speed relative to Ceres (as of 22h UT, or 2pm pacific on 26 Feb) is 70 m/s. Which fits fairly well with Pterich's timetable. He gives 69.67 m/s for 26 Feb.