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#340
by
kevin-rf
on 23 Nov, 2011 10:27
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Not throw an even wetter blanket on HEO storage, but that mean storing it in the Van Allen belts for several years. Not a healthy place. Also, while the probe is designed to spend years in space, the drop tank is not. They need to use it or risk complications.
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#341
by
Galactic Penguin SST
on 23 Nov, 2011 10:33
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Not throw an even wetter blanket on HEO storage, but that mean storing it in the Van Allen belts for several years. Not a healthy place. Also, while the probe is designed to spend years in space, the drop tank is not. They need to use it or risk complications.
Well, you can't reach a higher Earth orbit without making a burn and disposing the drop tank.... (the tank was designed to separate after the first burn to something like a ~4000 X 20000 km X 48 deg. orbit)
As for the radiation problem.... how about storing it in GEO?
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#342
by
Galactic Penguin SST
on 23 Nov, 2011 10:37
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#343
by
Cbased
on 23 Nov, 2011 10:45
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2) The probe has only responded with a 'bleep'. A computer with a crashed hard-drive will do that too but it can't do anything useful. Let's wait until regular uplink/downlink and is established and useful data is transferred before cheering;
No, it's better than that. The ground station in Perth sent the command to turn the transmitter on and received a signal straight away (just a carrier frequency). The station was not ready to receive real telemetry. They used a direct action command (bypassing the main computer/control unit). But the fact that the spacecraft reacted to this command is very good news.
3) This very limited signal was received only on one out of four comm attempts - This may imply changing antenna positioning (axial roll) or possibly issues with the probe's hardware
... or that the orbital position of the spacecraft was not known well enough.
4) The fact that the probe only responded whilst on Earth's dayside may indicate problems with the battery charger system.
Correct. The batteries were not designed to last that long.
So the spacecraft can only operate on the day side (getting power from solar panels)
I don't want to be overly negative but I hope this gives some indication of the challenges facing the team right now.
Let's call it - cautious optimism
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#344
by
Svetoslav
on 23 Nov, 2011 10:45
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http://ria.ru/science/20111123/495893243.htmlRussian Phobos-Grunt is in safe mode...
A source from the aerospace industry explains that P-G is possibly in safe mode and it always turns off each time when it goes into shadow of Earth.
The unnamed person also thinks why it was impossible to contact P-G with Russian space antennas - the spacecraft is above then only when it's in the shadow of Earth.
But the European station in Pert has contacted P-G when the spacecraft was in the sunny side of the Earth. It's the only period when there's electricity on board.
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#345
by
Cbased
on 23 Nov, 2011 11:00
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Apparently (according to NK forum and ESA) there will be 5 attempts to establish communications tomorrow (Moscow time):
00:25, 01:57, 03:32, 08:16, 09:49.
The station in Perth has got commands "turn transmitter on" and "turn telemetry on".
Hoping for the best - fingers crossed.
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#346
by
JimO
on 23 Nov, 2011 11:10
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I've been around RF signals too long NOT to worry the simple tonal signal
might turn out to be spurious. Was the antenna tracking the source across the sky? Was any doppler observed? That would make me feel a lot less worried.
But the report that the tone appeared right after the on command, and the explanation for other failures to receive tone [shadowing after batteries have failed], does provide a warm fuzzy feeling.
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#347
by
plutogno
on 23 Nov, 2011 11:40
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Well, you can't reach a higher Earth orbit without making a burn and disposing the drop tank....
Theoretically at least WSB orbits and lunar flybys could put F-G in a very high orbit at the expense of relatively little fuel. The same process in reverse could be used in 26 months to send the unlucky probe to Mars. Think of Hiten, Nozomi, Artemis and GRAIL
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#348
by
notsorandom
on 23 Nov, 2011 12:25
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Wow! Hats off those in Perth. They did an impressive job of aiming their antennas. There was speculation that the drop tank was covering the low gain antenna making communications impossible. The DSN has a facility at Canberra which is on the other side of the continent. Are there any assets there that can help?
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#349
by
cneth
on 23 Nov, 2011 13:12
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Well, this is quite exciting.
But this sudden safe mode 'discovery' is very puzzling. Surely the folks doing the troubleshooting should have known of this 'only listening when insolated' mode, after all, they designed it, right?
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#350
by
demorcef
on 23 Nov, 2011 13:43
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This is fantastic news. Now we need some more good luck and maybe life can be restored to our little probe.
Выздоравливайте скорее !
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#351
by
apollolanding
on 23 Nov, 2011 13:53
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Congrats to the ESA engineers for getting their antenna to track and communicate with F-G. For the sake of science (and all who worked on the mission) I hope some sort of productive communication can be established, a diagnosis is obtained and a fix can be worked up... a lot of ifs and a long shot to be sure but the ingenuity of aerospace engineers never ceases to amaze me so here's hoping some kind of science mission can be salvaged.
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#352
by
plutogno
on 23 Nov, 2011 14:17
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#353
by
aquanaut99
on 23 Nov, 2011 14:19
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Even assuming they can regain control of the probe, what options do they have, other than implementing a controlled crash back to Earth to prevent a later uncontrolled re-entry?
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#354
by
mr. mark
on 23 Nov, 2011 14:25
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Can they put the probe into a safe holding orbit for a 2013 burn to Mars?
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#355
by
Galactic Penguin SST
on 23 Nov, 2011 14:26
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This post on Universe Today seems to clear up the mess on the Mars transfer window. Apparently the November 21st date refers to the last day that allows Phobos-Grunt's return capsule to return to Earth during the 2013-2014 window, and the actual window of reaching Mars/Phobos in 2012 is actually a bit longer, lasting until mid-December for P-G.
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#356
by
plutogno
on 23 Nov, 2011 14:28
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#357
by
savuporo
on 23 Nov, 2011 14:30
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Data received from Phobos-Grunt were then transmitted from Perth to Russian mission controllers via ESA's Space Operations Centre, Darmstadt, Germany, for analysis.
So there is hope that there is more than just carrier frequency obtained ?
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#358
by
bolun
on 23 Nov, 2011 14:39
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#359
by
JimO
on 23 Nov, 2011 14:42
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This post on Universe Today seems to clear up the mess on the Mars transfer window. Apparently the November 21st date refers to the last day that allows Phobos-Grunt's return capsule to return to Earth during the 2013-2014 window, and the actual window of reaching Mars/Phobos in 2012 is actually a bit longer, lasting until mid-December for P-G.
I would caution about trusting the interpretation in that article. Since the lander has to wait over at Mars for more than a year, there is no problem making the return leg even if the arrival leg is delayed significantly. Trans-Earth insertion is decoupled from Mars arrival date.
What a delayed arrival MAY do is raise the required delta-V for Mars orbit insertion. It certainly also raises the required delta-V at Earth departure.
