Dust Storm- Opportunity EOM, the end of the beginning of a new era in robotic spaceflight Options

[fredk]

I suppose you may not need to resolve Oppy. In principle I could imagine comparing images of Perserverance Valley now with images before the storm under the same lighting conditions, and looking for signs of increased dust on the ground more generally. In principle.

In practice this sounds hard if not impossible. Can images at sufficiently similar lighting be obtained, especially given the changing season? And a current tau above the pre-storm level will surely confound a fair comparison due to the atmospheric dust contribution. And it's not clear how much of an increase of dust cover on the panels would be implied by some increase on the ground, due to the different surface characteristics.

[mcaplinger]

Maybe it might be possible to look for a glint (specular reflection) from the solar panels?

I think that's not possible given the orbital geometry; given the low tilt the imaging would have to happen around local noon, and MRO is in a roughly 3 PM orbit.

[djellison]

The one time we’ve seen a ‘glint’ via HiRise was off Spirit years after it died. And it was just lucky. I don’t believe it can be used quantitatively.

There is a huge back catalog of dust factor and tau data that’s been collated by people here.....one could quite easily see when cleaning events occur by plotting dust factor against Ls and looking for periods of general improvement.

[marsophile]

I think that's not possible given the orbital geometry; given the low tilt the imaging would have to happen around local noon, and MRO is in a roughly 3 PM orbit.

I think if an orbital pass was chosen to be about 22.5 degrees to the east of Opportunity, the geometry might be about right to hope for a reflection, since 3pm should mean a sun angle of 45 degrees from the zenith. Of course it would still take careful planning and a lot of luck.

[mcaplinger]

I think if an orbital pass was chosen to be about 22.5 degrees to the east of Opportunity...

I think that would be way off nadir, since from the MRO orbit the limb is only about 27 degrees of longitude from nadir. But I haven't studied the geometry carefully, and if there was an observed glint from Spirit there must be some way to make it work, though I don't remember what Spirit's tilt was.

However, I still argue that it's not diagnostic at all anyway.

[serpens]

Well we know that Opportunity is in a good position for panel cleaning events which is a plus. I would have thought that the real danger period would be as the dust settles and minimum temperatures start dropping while power levels are insufficient to recharge the batteries for heating.

[marsophile]

I'm afraid what you saw was an antenna briefly locking up on MRO as its orbital motion put it's nominal downlink frequency on top of the expected MER frequency due to Doppler shift.

Is it possible that the same thing could happen in reverse? That a low bit/sec signal from Opportunity might go unnoticed because it is misidentified as being from MRO or another mission? Something like this, for example:

[djellison]

No - 11b/sec on MAVEN is a regular LGA telemetry only check in. Moreover - in the same way we can go 'that's a false lock on MRO while looking for MERB' it's also similarly obvious if there's a false lock on MERB when looking for something else.

The data rate for Opportunity in various fault modes would also be unique compared to other Martian spacecraft.

Recommended reading - the DESCANSO Design and Performance Summary Series

https://descanso.jpl.nasa.gov/DPSummary/summary.html

[mcaplinger]

That a low bit/sec signal from Opportunity might go unnoticed because it is misidentified as being from MRO or another mission?

Being "in lock" is only a very early step in the whole decoding process that ends with digital packet data being produced. If a signal makes it all the way to the end, it has a unique spacecraft ID in it AFAIK, and shouldn't be confusable with anything else; even without the unique ID it's hard to confuse one spacecraft's packets with another's.

In listen-only mode, signals are recorded in wideband, not decoded in real time, and can be combed through later in much more detail than real time will permit. So if there's a signal in there, it will be found.

[marsophile]

However, I still argue that it's not diagnostic at all anyway.

Apart from the luminance, the color spectrum might also provide useful information on the combined attenuation due to the tau and the dust factor. If a glint could be obtained, even if it proved not to be diagnostic, I think the general public might be excited by the daring and audacity of the attempt.

However, the existing tilt of the rover (is it known?) might render the task impossible. A tilt in the wrong direction would be doubled in terms of the needed offset to get a reflection.

[djellison]

The exact pitch/roll/yaw are known.

[Explorer1]

From A.J.S. Rayl's latest report:

Actually, word is there is a plan to schedule the High Resolution Imaging Science Experiment (HiRISE) camera onboard MRO for imaging Opportunity sometime in September, when MRO orbits around Endeavour.

I'm sure we're all looking forward to seeing Opportunity, even if it remains silent at the time of the imagery.

[mcaplinger]

From A.J.S. Rayl's http://www.planetary.org/explore/space-top...pportunity.html :

“A lot of people don’t realize that when we had the campaign to listen for Spirit, that campaign was active listening the whole time, because of a mistake in the fault protection settings,” Squyres elaborated.

Maybe a lot of people don't realize that because it's never been written down anywhere publicly before now, at least as far as I know.

[fredk]

It's good to finally read some detail on the active/passive distinction. From the report:

the passive listening efforts would continue though until at least the end of January, Squyres said. “It’s a good plan. ‘Active listening’ really means trying to send commands to the rover, which is labor-intensive. It’s also probably unnecessary, since the rover should simply wake up and start talking to us on its own if and when there’s enough power,” he said. “Commanding shouldn’t even be necessary. So a fairly short period of active listening to cover all the bases, followed by a longer period passive listening makes sense.”

Still, "probably" and "shouldn't" aren't definitive. Is anyone aware of a scenario where we could regain contact actively but not passively? (I guess we don't have the mistake in the fault protection settings that Spirit had, so that shouldn't be a problem.)

[marsophile]

Maybe a lot of people don't realize that because it's never been written down anywhere publicly before now, at least as far as I know.

http://www.planetary.org/explore/space-top...mer-update.html

Is this the issue? (From the MER update from 2010 that you cited above.)

With the mission clock fault however, there is an unexpected and unintended consequence: the vehicle wakes up and expects to communicate using a comm window one hour later. “With that 20-minute up-too-long parameter, the rover wakes up and sets the comm window for an hour, and then shuts down after 20 minutes,” said Nelson. “And the comm window is volatile so -- poof -- it disappears!”