Rise or Fall
2015 May 23
Saturday, Day 143
Phobos-Grunt - Contact
After several weeks of silence following launch 2011 November 8, contact was established between Phobos-Grunt (or as some prefer - Fobos-Grunt) and a ground station near Perth in Australia. The station is operated by the European Space Agency.
It occurred 2011 November 22 at 20:25 UTC. The ESA report says that the ground station sent a trigger signal and Phobos-Grunt responded. However, what was received was a carrier signal without telemetry. A report from the Russian space agency, Roscosmos, made a point of saying that the communication occurred while the vehicle was in sunlight but did not elaborate further. Later in the day, Novosti expanded on this to explain that Phobos-Grunt has an "emergency mode" that switches off the transmitter when no power is flowing from the solar panels. It is meant for during the interplanetary cruise if the solar panels were to lose their lock on the Sun, rather than when orbiting the Earth where there is a regular 'switch' between night and day.
After many days of trying with no tangible result (see the diary and table further down the page), a rescue seems unlikely. Watchers have switched to waiting for the Phobos-Grunt orbit to decay to a point where re-entry occurs. There is an evolving table of reentry predictions on the Phobos-Grunt Reentry Watch page.
Looking at the geometry of the situation, the Roscosmos comment can be expanded upon. The map shows the location of Phobos-Grunt at 20:25 UTC, the time contact was established. It had already passed-by Perth and was descending in the sky. It had also just exited the Earth's shadow (the shaded area on the map), a scenario that fits in with the "emergency mode" described by Novosti (above).
Phobos-Grunt was again received, this time much more strongly and with telemetry, at the ESA Perth ground station when it entered sunlight on a 13Â° elevation pass between 18:09 and 18:16 UTC. The data was passed immediately to NPO Lavochkin, the spacecraft manufacturer, in Russia.
The next pass was relatively short and used only to upload some data via one of the spacecraft's low gain aerials. The remaining usable passes for the visbility period yielded no signals. It was expected to use the second of its low-gain aerials but either it was not pointed in Perth's direction or it was not working.
ESA said it would concentrate on two passes out of the set and that new commands would be uploaded. In the event, it tried for all the possible ones but with zero result.
During the course of Nov 25, ESA let it be known that the next attempts to contact Phobos-Grunt from Perth would be November 28 (Monday). At about the same time, Novosti carried a story that whatever was achieved, it would be too late to mount a Mars mission. Anything learned would be of academic interest for future missions. There is however some confusion because, during Nov 25, Novosti reported that ESA would make a single contact attempt that evening but did not report which pass. Nothing was forthcoming from ESA.
Indications are that communication attempts were maded from Baikonur but with no positive results either in terms of an orbit-raising, or a transmission from, Phobos-Grunt.
The Baikonur station appears to have made a single attempt to upload thruster firing data but it produced no result. The ESA plan was to transmit but not listen on four out of the five available passes (the initial one was probably ignored because eclipse exit was relatively late in the transit). Spacetrack data showed no orbit change overnight and a morning press release through Novosti confirmed it.
Given that Russian engineers managed to decode same some of the data received at Baikonur and that further listening attempts seem to have been abandoned, it may be that the data told them that there was nothing more or different to be received.
During the course of the day, ESA let it be known that there would be further communication attempts over the night of November 29/30 and that an aerial similar to the one at Perth was being added to its 15m dish at Maspalomas, Gran Carnaria.
An element set issued by Spacetrack for epoch 02:57 UTC indicated that, until that point the only significant variation in the orbit was down to atmospheric drag but it showed a small 'hiccup' in continuity that will only be confirmed by further element sets. In the event, it was a discontinuity in the Spacetrack data. With no indication of what thruster firing data Russia was attempting to upload, it is not possible to know when the firing(s) are to take place other than probably being later than 02:00 UTC. If they are timed to be detectable by Russian ground sensors then nothing is likely before the middle of the day when passes over Asia start to occur.
A Novosti press release around 06:00 UTC said that no response had occurred to the attempt to upload commands and that a transmission attempt would be made from ESA's station at Maspolomas, Gran Canaria later in the day. Gran Canaria sees two sets of passes daily on each of the northbound and southbound legs of the orbit, only the northbound set is currently usable as the southbound one has Phobos-Grunt in eclipse.
An indicator of the sparsity of information being released is that Novosti is now basing its reports on Spacetrack, rather than Russian, orbit data so it's narrative reports might equally not be 'from the horse's mouth'.
Maspalomas came into play today but with the transmitter aerial modifications incomplete. There was no result from what was probably an underpowered transmission.
November 30/December 1
Perth used a slightly different routine on two overnight (UTC) passes but with no result. This time the transmitter interleaved alternate blocks of data to load orbit raising command, and an instruction for transmitter to switch on (no telemetry) in order to confirm commands were accepted
Maspalomas had two usable passes in daylight and, with each, transmitted a real-time command for Phobos-Grunt to turn on its transmitter and return telemetry. It seems there was no success.
Had it been successful on the first pass then Baikonur had a window, when transmissions could have been detected, between Phobos-Grunt clearing the horizon at 13:01 UTC and entering eclipse at 13:06. The map shows the position of Phobos-Grunt - near Baikonur at the point of entering eclipse. On the second occasion it overflew Baikonur fully in eclipse.
Overnight, Perth had opportunities and attempted communication, again with no response. The actual communication plan is not known.
Maspalomas had two usable passes in daylight and, with each, communication was attempted with no result, The actual communication plan is not known.
After these two attempts, ESA announced that there would be no more. However, ESA remains available to assist further should there be a significant (but unlikely) change in Phobos-Grunt's fortunes.
Russia announced that further, undocumented, attempts to communicate from Russian ground stations over the previous few days had failed and the effort to receive signals had ceased. However periodic transmission of instructions to fire the engine will continue.
After the event Russia revealed that, following a special request, a contact attempt had been undertaken by the Maspalomas station.
ESA announced that it was back in the hunt and that attempts to upload real-time commands to fire the engine would be made from Maspalomas on all available passes over a period of three days. NPO Lavochkin's engineers believe that it is still alive and that if it can be coaxed into a higher orbit, it might give enough time for it to be coaxed back to life. In the event there was no reaction whatsoever from the spacecraft.
ESA announced that it would make two contact attempts from Maspalomas on December 13.
There were actually three opportunities on the day but only two of them (in the morning) that went on to cross Baikonur's horizon a few minutes after passing Maspalomas. They are detailed in the log below
Hinting that ESA's involvement had probably come finally to an end, Novosti carried a story to the effect that Russian attempts would be made right up to re-entry (expected around January 9) to get a response. Some components are expected to survive re-entry but the only significant one is the sample return container which is heat-shielded and designed to withstand the temperatures and forces involved.
On a separate note, about 16:00 UTC marked the start of a 30 hour period with the whole orbit in full sunlight. Under those conditions, were Phobos-Grunt to come alive, the 'emergency mode' that switched it off when out of sunlight would not be activated. The same might be true 1-2 days either side if Phobos-Grunt did not stay in eclipse long enough for the emergency mode to be triggered.
When ESA first got involved in looking for Phobos-Grunt, the exercise involved stations in Australia, French Guiana, the Canary Isles and Europe. In the event, first contact came November 22 through Perth in Australia. Efforts became concentrated on getting more signals by the same route because, if Phobos-Grunt was in a stable orientation, the alignment of transmitting and receiving aerials would be similar from day to day. Modifications were made to Perth's transmission arrangement to reduce the outgoing power to levels similar to what Phobos-Grunt would expect to see if it was on the way to Mars rather than 200-300 kilometres above the Earth.
November 28, news came that similar modifications were being made to ESA's ground station at Maspalomas on Gran Canaria. Two days later, the first communication attempt was made from there. After December 2, Perth dropped out of the equation and Maspalomas took over.
Maspalomas was seeing less daylight passes than Perth. At best it was two each day, compared with Perth's four or five. However, an advantage of using Maspalomas was that after Phobos-Grunt passed by, it arrived over the Baikonur tracking station about fifteen minutes later. If Phobos-Grunt was triggered into activity then Russia would hear of it almost immediately. It also reduced the workload for ESA as the Maspalomas station only had to transmit and didn't need to get involved in listening out.
On the map, the track shown is one of the Maspalomas passes on December 13.
The table below covers known tracking attempts starting Nov 23, but includes the initial observation from the ESA station near Perth on Nov 22. Only passes where Phobos-Grunt was not in eclipse are covered and many Russian attempts have not been documented. Any significant developments will be broadcast via the zarya.info feed.
NOTE 1: According to Novosti, one of the Perth passes Nov 24/25 was not tracked but it was unclear as to which one. However, ESA later stated that ALL FOUR of the passes were used to try and detect Phobos-Grunt.
NOTE 2: With one possible exception, there were no attempts from Perth for the nights of Nov 25/26, 26/27, 27/28 while ESA was catching up on a backlog of its own observations that resulted from concentrating on Phobos-Grunt.
NOTE 3: The Baikonur observations may be from the nearby tracking station at Dzhusaly.
NOTE 4: There are no reported communication attempts from any Russian ground station after November 28 although attempts continued. Russia simply failed to issue reports.
NOTE 5: Phobos-Grunt orbit parameters.
On December 14, the Scientific American web site published an article purporting to examine a claim that an American research station had damaged Phobos-Grunt with its radio transmissions. The station in question is America's High Frequency Active Auroral Research Program (HAARP) observatory at Gakona in Alaska..
The claim, that came originally from a senior Russian military figure, has no basis in actual events. Phobos-Grunt did not pass anywhere near Alaska until nearly fourteen hours after leaving Baikonur. Its problems had already manifested themselves. If they hadn't then Phobos-Grunt would have been well away from Earth by that time.
If the radio transmission in question was powerful enough to knock out Phobos-Grunt then there should be a lot of other satellites with owners scratching their heads over why they are no longer working.
The original comment was certainly ill-informed and may have been politically motivated. It's just unfortunate that Scientific American maybe asked the question with good intent but came up with an answer based on technical understanding and depth of research that was as flawed as the logic of the comment's originator.
Copyright © Robert Christy, all rights reserved
Reproduction in whole or in part without permission is prohibited