Philae Wakes Up! Options

[fredk]

That revised Philae position image was released last week (always best to cite the original).

[Habukaz]

...and we got more contact.

https://twitter.com/esaoperations/status/611894877417291776

[Greg Hullender]

Slightly more data on today's contacts. There were two contacts, each 2-minutes long. 185 packets of data were collected.

They didn't say when the next contact would be, but they ended with this:

"The Rosetta and Philae teams will be closely monitoring subsequent transmissions between the spacecraft, not only to better determine the health of the lander, but also to understand the length and frequency of available communication timeslots. This information is needed to determine when to upload new commands in order to restart science operations and, similarly, when the data can be downloaded."

http://blogs.esa.int/rosetta/2015/06/19/ro...-contact-again/

[alphasam]

A bit more info,

http://www.dlr.de/dlr/en/desktopdefault.as...#/gallery/17198

The two previous transmissions contained status information from early May showing Philae was at least awake by then.

[MahFL]

"In the meantime, new commands have been uploaded to Rosetta to further adjust its trajectory and distance from the comet to improve the radio visibility between the two spacecraft, with the first sets of thruster burns having taken place this past Wednesday and the next set planned for Saturday morning. The goal is to bring Rosetta to about 177 km from the comet nucleus and keep it in a range of latitudes that maximise opportunities for lander communication."

rosetta-and-philae-in-contact-again

[DoF]

Looks like contact was made today as well, although I haven't seen any reports about it.

[chuck0]

Yes, http://isee3.p3s.nl/philae/ again has been updated with new data from Saturday. Quite a bit more than on previous contacts so i would assume that the connection got more stable. Another interesting thing is that some kind of periodicity becomes apparent when looking at the data... i wonder what that is about. Anyways, it will be interesting to see whether they really can start to use for example the MUPUS PEN sensors next week.

[nprev]

Periodicity, huh? Could be a great many things. I'd assume that the lander-orbiter link is the highest priority right now, so I'm not sure what would interrupt it except for Rosetta downlinking that data to Earth. Does it perhaps correlate to Rosetta's orbital period around the comet at this time?

[chuck0]

Really hard to say what the source is since i dont think the time axis in that chart always corresponds to the actual time the data was recorded (the DLR blog mentioned that some data was from May...). Instead it seems like it is the time it was received on the ground. Anyways it nearly looks like a heartbeat



The reported time between those spikes in current is really short (around five seconds).

[stone]

Instead it seems like it is the time it was received on the ground. Anyways it nearly looks like a heartbeat

Could it be that the time stamp is the receiving at the rosetta orbiter?

I think at -135°C temperature and no energy at all the internal time keeping of Philae became bogous anyway.
There was no downlink to Philae so were should the timing come from?

[Herobrine]

I do believe the timestamps originate on the ground, or on Rosetta, and are not based on the data from the lander. There are multiple reasons to think this is true, but the most telling reason is that this data is supposed to be from much earlier, perhaps even May, from what I've heard, but the timestamps appear to correspond with the days the data were received.

I've been working from the assumption that the cyclical nature of the battery data reflects the day/night cycle from Philae's location.
I dump the raw data from that server to a CSV file and play with it in Excel.
I like to imagine that Philae is trying to describe the surrounding terrain to me with its battery data as the shadows move across the panels.

That's just multiple cycles of one of the data series since Philae woke up, lined up side-by-side to form a surface, in case you're curious. Interestingly (to me), that particular data series doesn't seem to show up in the charts on the telemetry page, and the series aren't labeled in the raw data from the server, so I have no idea what it even represents.
(I dug through the javascript of that page once, back in November, to figure out what was what and what it was doing to the data before displaying it, but I've forgotten all of that and don't feel like doing it again right now.)

Here's a graph of the time (in milliseconds) between data points over the span of the new data (since the 14th or whenever):

Vertical axis is logarithmic. The highest peak corresponds to a gap of 4 days 16 hours. Assuming the timestamps are added by Rosetta, I'd like to think the relatively flat, long stretch is indicative of a more stable connection. If they're added on the ground, they could just represent different downlink modes on DSN or something; who knows; I really lack the context and background to draw any informed conclusions from any of this.

Edit/Update:
There were a few tweets from @DutchSpace over the weekend about the telemetry.

https://twitter.com/DutchSpace/status/612163178101907456 (includes chart)

After orbit change of @ESA_Rosetta it looks like we got another telemetry blip from @Philae2014 #lifeonacomet

https://twitter.com/DutchSpace/status/612167466211495936 (includes chart)

As @Philae2014 is sending more telemetry blips I can update my graph, will have to fine tune it over the weekend.

https://twitter.com/DutchSpace/status/612539793386401792 (includes chart)

Looks like the @ESA_Rosetta orbit changed worked, much more data points from @Philae2014 coming in

I noticed that the label for the bottom chart has been updated so it looks like there is/was some work being done to improve the telemetry page.

As long as I'm editing, I might as well throw out more wild speculation. If the number of data points is correlated with the number of packets received, then, given the 300 packets reported for the first communication session, and the 84 data points for the first block of new telemetry data, one could guess that the current total of 336 data points received since wake-up indicates about 1200 packets (actually, the math of 336 * 300 / 84 comes out to exactly 1200) have been received so far out of the I-forget-how-many packets they said were stored on Philae.

[alphasam]

Interesting, if not entirely positive, article from Le Point (in French) apparently regarding conversations with Gaudon,

http://www.lepoint.fr/astronomie/mission-r...938939_1925.php

Gist is it says there were two further contacts over the weekend on Saturday and Sunday, but none with uninterrupted communication windows longer than 2 minutes. They need at least 15 minute windows apparrently to upload commands to Philae. Says they'll try to get Rosetta down to 160km around Wednesday.

[scalbers]

Interesting they mention uncertainty in the orientation of Philae. I had thought they earlier stated they had a good sense of that. And the mosaic I had made, with the help of Mattias' sun vector also gives some potential information about orientation, with an estimated 80 degree tilt compared with the "local" surface. We can even see the CONSERT antenna in the mosaic. The specification of orientation is better though before the rotation maneuver, though we can get a sense of this by the shift in the ROLIS images before/after.

[alphasam]

I suspect the point is Philae might not be in the orientation they left it, if it is tilted more on its head that might explain the communication difficulties.

[scalbers]

Makes sense that Philae could have shifted. I believe though the CONSERT antenna projects off the lower part of one of the sides, unless there's another reason the head (top) would be important.