What is up with the tiny Ulysses spacecraft that was launched in 1990 to study the solar whatever at high lattitudes? Last I heard it was in danger of http://science.nasa.gov/headlines/y2004/17mar_ulysses.htm?list24876 because the RTG power was running low and at aphelion there was a risk of the hydrazine freezing/exploding in its propulsion system. Well that was like a year ago and I haven't heard anything since. It http://ulysses-ops.jpl.esa.int/ulsfct/rgpCafe/solsys/solsys.html like it should've passed aphelion by now and should be out of danger.....
Its been going up there for over a full solar cycle, is it one of the missions on the chopping block because of the new humans on moon/mars thing?
Yes I havnt heard much news about Ulysses since it flew trough the tail of Hyakutake, (and got some personal exitement over same comet. Me and a friend watched it span more than half of the sky!)
The mission page say its operational and with funding until March 2008:
http://ulysses.esa.int/science-e/www/area/index.cfm?fareaid=11
http://ulysses-ops.jpl.esa.int/ulsfct/opssumm.html
Current operations
.....
23 September Routine Operations
24 September Routine Operations
25 September Routine Operations
268.16:43-17:06 23m realtime 8192 bps plus 21m playback 512 bps data lost due
(268.16:22-16:43) to DSS-14 inability to acquire caused by bad predict file.
DR G106105 refers.
26 September KEP IFC - cancelled as instrument is off.
Earth pointing manoeuvre w/power save - 269.11:47 SCET
...
Doug
Hmmm looks like alot of the instruments are switched off "HUS, BAM-E, KEP EPAC/GAS and STO2 are off." http://ulysses-ops.jpl.esa.int/ulsfct/reportframe.html.
Fifteen years after its launch, the grand ESA/NASA Ulysses space mission is
still going strong, orbiting the Sun and continuing to tell exciting stories
about our nearest star.
More at:
http://www.esa.int/esaSC/SEMTNC5Y3EE_index_0.html
Ulysses 15th Anniversary
Video: http://www.jpl.nasa.gov/videos/solar_system/UlyssesWebVideoOct7-cc.mov (26.5 MB)
October 6, 1990 to October 6, 2005
Neat video. Does anyone know how to unlock the easter egg in http://ulysses-ops.jpl.esa.int/ulsfct/rgpCafe/solsys/solsys.htmlpage? It's driving me nuts. Every once in a while an icon that looks like a keyhole will appear on the applet but if I try to click on it nothing happens and then it disappears!.........
oh. well that's not very exciting is it.
Ulysses embarks on third set of polar passes
http://www.esa.int/esaCP/SEMWPIUXJUE_index_0.html
For those interested I've posted at the http://www.spaceurope.blogspot.com a small query with Dr. Richard Marsden about Ulysses.
ustrax: interesting. But what's up with the mid-sentence colour changes? sorry to nitpick, but it's something I find a bit annoying when reading. I'm used to there being a link if there are colour changes in sentences. For the rest, interesting website. Keep it up!
ah I see now.
There goes Ulysses...http://www.esa.int/esaSC/SEMUHTN2UXE_index_0.html...
I really enjoy Dr. Marsden' http://www.spaceurope.blogspot.com:
"It's amazing to think that a satellite that was designed in the mid-1970's
and built in the early 1980's is still operating perfectly in 2007!"
http://www.esa.int/esaCP/SEMUHTN2UXE_index_0.html
ESA
7 February 2007
I agree with ustrax; the longevity of this spacecraft (and others) is astounding. These are arguably among the most complex devices ever built, yet without hands-on maintenance, periodic overhauls, etc., they just keep going. Wonder if the space agencies might be interested in building a few cars on the side...
All that aside, how much longer can Ulysses keep going given this new power conservation strategy? Also, is there any possibility that it will re-encounter Jupiter at some point?
Ulysses Update:
http://www.spaceref.com/news/viewpr.nl.html?pid=21934
This is the old argument they went through when they were designing the Apollo system. They asked themselves, how much would it cost to develop a system that would have a 100% reliability rating, that could never fail and never, ever endanger the lives of any of the crews.
They decided it would cost more than the entire American gross national product from then to their deadline (the "end of the decade") to accomplish that, and it would likely result in a first manned lunar landing sometime around 1980.
They also figured they could develop Apollo for about five billion dollars if they were willing to lose about half of the crews they launched.
They settled on having a 90% chance of completing any given mission, and a 99% chance of getting any given crew back alive. That determination *alone* set the cost of the program at about $25 billion in 1960s dollars.
So, yes, you can pursue perfection. Just understand that, first, you'll never achieve it, and second, that you'll spend an *awful* lot of time and money trying to get there.
The better is the mortal enemy of the good enough...
-the other Doug
We'll miss http://www.esa.int/esaSC/SEM6UE3CXCF_index_0.html...
Well - there's a lot of science to be had from the archives, and while it's always sad to see a spacecraft go, it's always a bonus to get some DSN time back.
Doug
You know, for all the flack that ESA's press folks get, I have to say that their framing of this story is pretty apt. Usually this sort of thing ends up reported in the press as "BILLION EURO SPACECRAFT MALFUNCTION" not http://news.google.com/news?hl=en&ned=us&q=ulysses&btnG=Search+News
"End of the odyssey for brave space probe Ulysses"
"Ulysses mission coming to a natural end"
I'm hoping that this is how MER goes out - with a proud, somber moment.
Doug
Looks like my old thread was just a few years too early! I'm not criticizing the decision to switch off the HGA but I want to understand exactly what happened. They switched off the 60W HGA in attempt to divert the extra energy to the heater and science instruments instead but found that not only would the HGA not turn back on again but they couldn't even re-route the power to the heaters either. Right? But is the fuel freezing faster than expected now due to the fact that those 60W which would have been dissipated in the HGA subsystem are wasted out the RTG?
Basically, yes. That's my understanding of it. The HGA power down either caused or unearthed a power subsystem problem that they didn't know about.
Doug
Remember that Ulysses needs to periodically re-orient it's high-gain antenna to point toward Earth. Though it's now irrelevant, the X-band beam is several times narrower than the S-band beam due to the diffraction limit of the dish antenna. We're moving out of the S-band beam, I presume, and data rates will drop to useless levels. There may be an omni antenna (I'd presume there is) for tracking immediately post-launch, but data rates would be like the raw data rate (before heroic efforts) of Galileo at Jupiter or worse, and depending on spacecraft orientation, might drop to zero for months or years. The spacecraft might well continue to transmit for some more years, but it's mission is essentially about to end.
Thermal Constraints of the Reaction Control Subsystem
From: http://ulysses-ops.jpl.esa.int/ulsfct//spacecraft/scframe.html
Fuel-bearing components are specified to be kept above 5°C. This is to prevent the fuel, hydrazine, from freezing, which would cause two problems. Firstly, the fuel would not flow to the thrusters and no manoeuvres would be possible. Secondly, if the fuel were to subsequently thaw, pockets of expanding liquid could form possibly rupturing RCS sections.
During the prime mission (1990-1995), meeting this requirement was not difficult, but with RTG power levels becoming so low it is no longer possible to keep remote RCS components above (5+margin)°C, particularly when the margins have been made particularly generous. In order to keep as much of the payload operating as safely possible, it is necessary to trim thermal margins to the lowest level. This in turn necessitates careful calibration of the spacecraft Thermal Model against in-flight temperature data.
The Reaction Control Subsystem (RCS) has several thermistors that measure component temperatures directly, shown on the right. There are also thermistors elsewhere on the spacecraft that can be used to infer RCS component temperatures.
Early in the mission, the available telemetry and generous thermal margins were sufficient to ensure compliance, however with steadily decreasing power availability, greater scrutiny of margins and more insight on the thermal behavior of all RCS components was necessary.
- - -
Sounds as if since 1995 things have been dicey when themal heating was low... Hydrazine freezes at 34 F (4 C) so holding temps above 5 C is a minimum requirement.
Rob
I know that during the Jupiter Distant Encounter in February of 2004, Ulysses had to turn its tape recorder off to run all of its instruments at once. However, during the ~40 days around the encounter, it had round-the-clock DSN coverage, so it had little effect. Once Ulysses began approaching the sun again, it was able to turn its heaters off, freeing up power.
For most of that time it should be away from major influences. However, when I run the numbers, I am seeing a Jupiter flyby in 2092 that is fairly close and would extend the orbit too far out to be thrown out of the solar system in 2098. In fact, at least on the "kiloyear" level, the orbit looks stable.
Yep, I made a stupid mistake. Or even two.
As for the solar light pressure, that's significant pertubator indeed. When I entered actual Ulysses area-to-mass ratio and size into the HORIZONS, results were changed dramatically. For example, Jupiter-2098 encounter:
This paper from 2004 tells us that the "freezing" of Ulysses was understood long ago.
It explains various techniques during the extended mission, including shutting off the X-band transmitter, to save power to keep going UNTIL MARCH 2008.
www.vega-group.com/assets/documents/10000207ExtendingtheUlyssesMissionto2008.PDF
Here is a tiny url!
http://tinyurl.com/26kaan
So Ulysses has reached the end of her odyssey, as planned long ago.
Rob
From Emily's blog on planetary.org about Ulysses: "In preparation for the mission's end I started rereading the Odyssey to look for a good epitaph. I haven't come across anything yet..."
Surely Teiresias' speech in Book 11 about how Odysseus will die: "It shall come to you out of the sea, death in his gentlest guise."
There are some fine lines in Tennyson's poem Ulysses that would fit:
To follow knowledge like a sinking star,
Beyond the utmost bound of human thought.
To sail beyond the sunset, and the baths
Of all the western stars, until I die.
To strive, to seek, to find, and not to yield.
Bill
Thanks for the tip, Mike. Haven't gotten to book 11 yet.
Mongo, everyone else in the blogosphere was quoting Tennyson and Joyce -- I wanted to do something different, and anyway I'd had that Fagles translation on my "to be read" bookshelf for a decade and hadn't read it yet. This made a good excuse!
--Emily
From Dante's Commedia (Inferno XXVI):
'O brothers,' said I, 'who through a hundred thousand perils have reached the West, to this so little vigil of your senses that remains be ye unwilling to deny, the experience, following the sun, of the world that hath no people. Consider ye your origin; ye were not made to live as brutes, but for pursuit of virtue and of knowledge.'
http://pd.sparknotes.com/poetry/inferno/section27.html
or if you prefer it in the original Italian:
"O frati", dissi, "che per cento milia
perigli siete giunti a l'occidente,
a questa tanto picciola vigilia
d'i nostri sensi ch'è del rimanente
non vogliate negar l'esperïenza,
di retro al sol, del mondo sanza gente.
Considerate la vostra semenza:
fatti non foste a viver come bruti,
ma per seguir virtute e canoscenza".
By the way, Ulysses received its name from Dante's sentence about "following the Sun"
Looks like news regarding the death of Ulysses may have been a little premature.
http://www.spaceflightnow.com/news/n0804/15ulysses/
http://www.esa.int/esaCP/SEMEVQNKRGF_index_0.html
From the "programmes in progress" section of the http://www.esa.int/esaCP/SEMA8LUG3HF_index_0.html
The third northern solar polar pass was completed on 15 March. In spite of the reduced data rates following the X-band anomaly in mid-January and the transition to an S-band mission, key arameters
characterising the solar wind, magnetic field and energetic particles continued to be measured. The picture that emerges shows great similarity to that observed in 1995, during the first northern polar pass, with the spacecraft immersed in the fast solar wind flowing from the Sun’s northern polar coronal hole.
Efforts to delay hydrazine freezing will continue in the coming months. It is very difficult to estimate exactly when the hydrazine will freeze since predictions are based on thermal modelling rather than actual temperature measurements in telemetry. However, a projected mission operations end date of 1 July 2008 has been agreed. It is possible that operations could continue beyond that date but it is also possible that the mission will end earlier. Once freezing occurs, it may be possible to thaw the fuel again for a while by switching off instruments but the science mission will essentially be over. When thawing is no longer possible, the loss of manoeuvrability will result in an increasing Earth off-pointing angle and the loss of telemetry after about a week.
Today at ESA Headquarters, the Ulysses Legacy press conference
http://www.esa.int/esaSC/SEMPEQUG3HF_index_0_ov.html
Today is June 30th, so folks, say goodbye to old Ulysses, he's heading home at last... End-of-Mission July 1st, 2008.
Rob
A sad day to be sure, but also a happy one. Could you ask for a more successful and long-lived mission? What a wonderful tribute Ulysses' longevity is to the scientists and engineers who designed and built it.
"A man of genius makes no mistakes. His errors are volitional and are the portals of discovery."
-Joyce
Yes, a hugely successful mission... many congrats to all involved. There's still a huge amount of science hidden in all those squiggly plots that it's produced - I'm sure it'll be a few decades until we fully appreciate its legacy.
<---- image at left shows Ulysses's 1996 comet Hyakutake encounter, in case it isn't obvious!
Ulysses hanging on valiantly
http://www.esa.int/esaCP/SEMKWKSHKHF_index_0.html
Humm...http://www.nasa.gov/home/hqnews/2008/sep/HQ_M08176_Ulysses_teleconference.html?...any idea of what kind of changes we might be talking about here?...
Guess we'll have more details tomorrow...
That should indeed be interesting. I assume the phrase "50-year low" means that prior to the IGY and the orbiting of the first satellites, there were no good measurements of the solar wind, so it could easily be much longer than 50 years since the present levels were reached. I guess if that trend continues for a couple decades it will be a good time for people to go to Mars, as long as no solar sails are involved.
I'm starting to get the chills...Can it be related to http://wattsupwiththat.com/2008/02/13/where-have-all-the-sunspots-gone/?...
Don't fret, a new http://spaceweather.com/images2008/22sep08/midi_lab.jpg?PHPSESSID=u3e0moub541tbsc2ks9a3kjkr4 just appeared today.
http://www.jpl.nasa.gov/news/news.cfm?release=2008-178 finds that the solar wind pressure and magnetic field strength is 20% lower than the previous solar cycle, and the lowest since such measurements began.
Implications are that Voyager 1 and 2 could reach the heliopause sooner than predicted, if this trend continues.
Climatology's been ruled off-topic for UMSF I'm afraid. For alternative forums, you may find http://www.google.co.uk/search?hl=en&safe=off&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=solar+sun+activity+sunspots+site%3Arealclimate.org&spell=1 of interest (or not )
There are status updates on Ulysses at http://ulysses-ops.jpl.esa.int/ulsfct/the_odyssey_continues.html
This is the latest, dated 11 December:
Dear Ulysses colleagues,
It has been a couple of months since my last status report. That's
because nothing much has changed. We are continuing with our S-band
science mission and typically we are now tracking once a day for
about 2 to 4 hours. We don't want to increase pass durations much
more than that because the temperature of the TWTA radiator panel
(close to the cold hydrazine pipework) now falls rapidly when we
switch the S-band transmitter on. But we are looking to increase our
tracking time by taking two short passes per day separated by enough
time for the radiator panel temperature to rise again.
The data we have been getting recently has been of very good quality.
The spacecraft-Earth distance has been decreasing and the link margin
has increased to a point where we don't need to drop to 256 bps very
often. In fact, we are close to being able to support 1024 bps which
would enable us to get data from the tape recorder again. We're
keeping a very close eye on the downlink SNR and we'll try 1k data
again if we think the data quality won't be degraded. No promises though.
There's another benefit from the low Earth range when coupled with
the fairly low Earth drift rate that we're experiencing this month.
If the hydrazine froze or ran out tomorrow, we could continue to
acquire telemetry for around 20 days before the High Gain Antenna
offpointing was too great to support even 128 bps. That's compared to
about 5 days if the fuel had frozen back in May or June this year.
However, this is a short-lived effect and by February next year,
we'll only have 8 days of data before the end.
The latest mission status. Ulysses is still alive!
Status report: 20-Feb-2009
Date: Thu, 20 Feb 2009 11:45:38 -0800
From: Nigel Angold
Subject: Ulysses Status Update 5
Dear Ulysses colleagues,
Yesterday was mission day 6712 and we surpassed 400 days of S-band
mission operations. Given that we thought the spacecraft would only
survive a few months after the X-band transmitter failure on 15
January 2008, that's pretty good going!
The last month or so has seen a dramatic increase in data return.
This is due in part to a request by NASA HQ for additional DSN
coverage and also due to the fact that we can record and play back
data again on board the spacecraft. That's possible because the
spacecraft-Earth distance is low enough to support a 1024 bps
telemetry data rate at the moment (this situation will last until
sometime in mid-March). I've attached a plot of our weekly data
return percentages which clearly shows the recent improvements.
As far as the hydrazine is concerned, it's obviously not frozen yet,
but there can't be very much left. Our estimate is that we have
almost no fuel left even using our best-case estimates. However, it's
very difficult to get an exact figure of fuel usage over the mission
given that we have had about 3 years of closed-loop conscan
operations to control nutation when the spacecraft fired the thruster
autonomously. During those periods, we had to estimate the number of
pulses fired by monitoring the increase in catalyst bed temperature
after each period of thruster activity which is not the easiest thing
to do. So the bad news is that we don't have an exact estimate of how
much fuel is left but the good news is that it's still above zero!
We hope that the data returned is continuing to excite you as the
solar activity slowly begins to increase.
Best regards,
Nigel
I was in JPL's Space Flight Operations Facility (SFOF) yesterday afternoon and saw a scrolling display indicating that, at that moment, the DSN was receiving data from Ulysses. So it was still alive as of about 00:00 March 17 UTC...
I would love it if it picked up one last comet tail!
The day has finally come! The last day for mission operations on Ulysses will be 30th June 2009 (see newsflash item on http://ulysses-ops.jpl.esa.int/). The LAST ground station pass of the mission is currently scheduled for 30th June 2009 over the Madrid DSN 70m station (DSS-63) from around 15:25 to 20:20 UTC (08:25 to 13:20 PDT). This will be a full year after the originally announced mission end date of 1-Jul-2008!
An open-loop slew manoeuvre will be executed before the start of the pass to set up the spacecraft to point directly at the Earth for the middle of the pass in order to maximise the downlink margin. Due to the short notice and low priority for DSN allocation, a full decommissioning of the spacecraft (including some end-of-mission engineering tests that a number of former and present Ulyssess engineers have been waiting to try out) will not be carried out.
It is expected that the events in the Ulysses mission support area at JPL leading up to the ceremonial last command to the spacecraft will be carried live on real-time streaming video and/or with mission ops blog update in real-time. Check http://ulysses-ops.jpl.esa.int/ often for announcements and the timeline for the final day of operations. The mission ops team members can now all be counted on the fingers of one hand, so plans can change ...
... so long and thanks for all the fish ...
The little spacecraft that could... and DID from Oct. 6, 1990 to June 20, 2009. STS-41 got you started, but the rest was on your own!
Fare the well, good friend.
-Rob
Man I saw the launch live at Cape Canaveral. I was still in high school then. Now I have 3 kids, the oldest half-way through primary. And the mission lasted for that long. Amazing.
From the mission ops blog:
While Goldstone is down, the torch has been passed to the Canberra DSN.
We are uplinking to Ulysses and Madrid will be receiving its last telemetry before bye, bye.
(this is the second time we've said goodbye, and most likely the last)
So long Ulysses and thanks for all the data!
"The thunder and the sunshine, and opposed
Free hearts, free foreheads you and I are old;
Old age had yet his honour and his toil;
Death closes all: but something ere the end,
Some work of noble note, may yet be done,
Not unbecoming men that strove with Gods.
The lights begin to twinkle from the rocks:
The long day wanes: the slow moon climbs: the deep
Moans round with many voices. Come, my friends,
'Tis not too late to seek a newer world.
Push off, and sitting well in order smite
The sounding furrows; for my purpose holds
To sail beyond the sunset, and the baths
Of all the western stars, until I die."
Excert from Ulysses by Alfred Lord Tennyson
Ulysses has just been switched off in good config (i.e. all off except receiver and sun tracker) if I understood the broadcast correctly. Farewell
Thank you and farewell Ulysses
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)