What's Up With Ulysses?, alive? dead? cancelled soon? Options

[deglr6328]

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 dying 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 looks 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?

[Guest_Myran_*]

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/....cfm?fareaid=11

[djellison]

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

[deglr6328]

Hmmm looks like alot of the instruments are switched off "HUS, BAM-E, KEP EPAC/GAS and STO2 are off." from here.

[ynyralmaen]

Hmmm looks like alot of the instruments are switched off "HUS, BAM-E, KEP EPAC/GAS and STO2 are off." from here.

That's due to power-saving measures. As the output from the RTGs is decreasing, not all the instruments can be operated at once. The (arguably) "key" instruments for monitoring solar wind conditions, wind composition, and the interplanetary magnetic field are all on, and providing near-continuous, unique data of excellent quality.

It's unfortunate that all the other instruments cannot currently operate at once... there is some swapping of operation time going on between the instruments, and some instruments are more likely to be kept on because they're providing heat that prevents the hydrazine from freezing at key locations in the fuel lines. As Ulysses nears the Sun again over the next couple of years, the heaters will not be required so much, freeing up power to operate more of the instruments again.

Funding has been approved by ESA and NASA to the end of the third fast latitude scan in 2008 (when Ulysses goes from solar pole to pole in 10 months). As a result of the change of focus at NASA, they're reviewing their funding for Ulysses and around 10 other missions, including Voyager. A loss of any of these extended missions would be a terrible waste - they're providing excellent, valuable data for a relatively tiny outlay. Ulysses is particularly unique - it's probably going to be a very long time before a spacecraft is put into a near-polar solar orbit again, so the data are extremely valuable.

As well as providing the valuable out-of-ecliptic heliospheric data that it was primarily designed to do, Ulysses did cross a second comet tail in 2000 (McNaught-Hartley), and performed unique observations of Jupiter last year. See the
Ulysses Status Reports for more information.

[ljk4-1]

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

[SigurRosFan]

Ulysses 15th Anniversary

Video: http://www.jpl.nasa.gov/videos/solar_syste...ideoOct7-cc.mov (26.5 MB)

October 6, 1990 to October 6, 2005

[deglr6328]

Neat video. Does anyone know how to unlock the easter egg in thispage? 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!.........

[tfisher]

Does anyone know how to unlock the easter egg in this page? 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!.........

I clicked around randomly in the applet for a couple of minutes and seemed to hit it eventually by chance. It just adds options to see the orbits of outer planets: Saturn, Uranus, Neptune, Pluto.

[deglr6328]

oh. well that's not very exciting is it.

[Rakhir]

Ulysses embarks on third set of polar passes

http://www.esa.int/esaCP/SEMWPIUXJUE_index_0.html

[The Messenger]

Ulysses embarks on third set of polar passes

http://www.esa.int/esaCP/SEMWPIUXJUE_index_0.html

I wandered around and found this webpage:

http://ulysses-ops.jpl.esa.int/ulsfct/orbits.html

Which includes current orbital data.

[ustrax]

For those interested I've posted at the spaceurope blog a small query with Dr. Richard Marsden about Ulysses.

[remcook]

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!

[ustrax]

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!

Thanks remcook, it is always good to have some feedback.
About the colour change...I'm still looking for an editing style...
It is just a way of differencing my words from the guest's ones.
Looks like it's not the better solution.
I'll think about another way of doing it.

Once more, thanks for visiting it, you're welcome, some more queries under way and future surprises being cooked...As this guys use to say...Stay tuned!

[remcook]

ah I see now.

[ustrax]

There goes Ulysses...again...

I really enjoy Dr. Marsden' updates:

"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!"

[Guest_AlexBlackwell_*]

Ulysses scores a hat-trick
ESA
7 February 2007

[nprev]

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?

[Paolo]

Also, is there any possibility that it will re-encounter Jupiter at some point?

Back when I was in university, a dozen of years ago I played with simulating Ulysses' orbit. In that occasion I "discovered" the second flyby of 2003.
Ulysses crosses Jupiter's orbit every 6.5 years, and approaches it every 13 years, but IIRC, the encounter distance is increasing and there will be no more flybys during all of the 21st century.

[Jeff7]

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?

I figure that they've probably got some pretty tight tolerances on these components. What I'm learning in my engineering classes is that tight tolerances are expensive. According to my Product Design professor, a Professional Engineer, they probably could design cars that would come with lifetime warranties. But they might cost $500,000 each, or more. Parts would need to be made out of more corrosion-resistant materials (more expensive), more parts wouldn't pass inspection because they'd be out of tolerance (higher manufacturing costs, and more time required to manufacture, which also = higher costs), and you might need more highly skilled engineers and machinists to properly design and construct this super-accurate car.

If they manufactured the MER's to the tolerances you probably find in the consumer auto industry, the rovers might never have left their landers.

Something else to consider - car manufacturers want you to buy a new car every so often. A car that might fail eventually increases your chance of buying again. NASA and JPL don't expect a lot of that sort of return business for most of their designs.

[centsworth_II]

A car that might fail eventually increases your chance of buying again.

But not from that manufacturer. I think car failure is due mostly to keeping costs down,
not planned shoddy workmanship. How much would a car built to NASA specifications cost?

[Littlebit]

Ulysses Update:

http://www.spaceref.com/news/viewpr.nl.html?pid=21934

[Jeff7]

But not from that manufacturer. I think car failure is due mostly to keeping costs down,
not planned shoddy workmanship. How much would a car built to NASA specifications cost?

It depends how long it lasted, and it depends on the person. I doesn't have to last long. Just long enough. If it was long enough, the person may rather stay with a brand whose quirks and issues they know, rather than risk venturing into the unknown, buying something different that might be much worse.
And maybe it's not planned, but the engineers making it have to know what's going to happen. Heck, one of the equations I've learned has "reliability factor" built into it. What reliability do you want? 50%? 90%? 99.9%? Different percentages have different numbers (1 for 50%, .75 for 99.9%) that go into determining endurance strengths and allowable stresses to give the certain reliability rating.
I guess it's not planned so much as it is a side effect.

How much would a car built to NASA spec cost? See the post you quoted me out of.


It'll be interesting to see how much longer it'll last. They seem to have a fair level of confidence in it:
"The definitive proof will come when Ulysses measures the temperature of the north polar coronal during the next 15 months."

[dvandorn]

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

[David]

They settled on having a 90% chance of completing any given mission, and a 99% chance of getting any given crew back alive.

Which are remarkably accurate estimates: they lost one mission out of 11 and 0 astronauts out of 33 (though they came pretty close).

[ustrax]

We'll miss you...

[djellison]

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

[ilbasso]

...and a 99% chance of getting any given crew back alive.

I can't remember who said it, but someone once commented that all the safety features of modern cars - multiple airbags, seatbelts, etc. - actually cause more crashes, with people driving less safely because they assume they'll survive an impact. The person said, "Imagine how much more safely we would drive if our cars had foot-long spikes extending from the steering column and ending just in front of our chests. You wouldn't DARE make a stupid move or tailgate someone!" Think how much cheaper that would make our cars - a spike is a lot cheaper than an airbag!

[stevesliva]

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=...tnG=Search+News
"End of the odyssey for brave space probe Ulysses"
"Ulysses mission coming to a natural end"

[djellison]

I'm hoping that this is how MER goes out - with a proud, somber moment.

Doug

[peter59]

"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!"

It's not very great achievement, Ulysses at last was launched in 1990. Pioneer 6, the first in a series of solar-orbiting satellites was launched December 16, 1965. Although the spacecraft have not been regularly tracked for science data return in recent years, a successful telemetry contact with Pioneer 6 was made on December 8, 2000 to celebrate 35 years of continuous operation since launch. As of March 15, 2006, Pioneer 6 is still described as "extant", and is the oldest operating space probe (if still operating).

[IM4]

Back when I was in university, a dozen of years ago I played with simulating Ulysses' orbit. In that occasion I "discovered" the second flyby of 2003.
Ulysses crosses Jupiter's orbit every 6.5 years, and approaches it every 13 years, but IIRC, the encounter distance is increasing and there will be no more flybys during all of the 21st century.

I explored Ulysses orbit evolution with JPL HORIZONS system. Here are some interesting encounters till the end of XXI century:

CODE

          Date (CT)       Body  CA Dist      Vrel
  ----------------------  -----  --------  ------
  A.D. 1992 Feb 08.78380  Juptr  0.006795  20.895
  A.D. 2004 Feb 04.98546  Juptr  0.804396  13.984
  A.D. 2086 Nov 13.65625  Juptr  0.780194  14.070
  A.D. 2095 Nov 01.78213  Mars   0.056797  37.722
  A.D. 2098 Nov 07.59152  Juptr  0.004053  24.594

November 7, 2098 Ulysses will be kicked out of the Solar system by Jupiter's gravity. Spacecraft's final trajectory will be highly hyperbolic (eccentricity~1.42), so it will be travelling very fast and one day, thousands years from now, Ulysses will reach some star.

[deglr6328]

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?

[djellison]

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

[edstrick]

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.

[mcaplinger]

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.

Certainly once the s/c loses attitude control the mission is essentially over.
The S-band and X-band both go through the high-gain antenna, but the S-band output power is only 5 watts compared to 20 on X-band, so the maximum data rate is pretty limited (I believe 128 bps compared to 1024 bps on X-band through DSN 34m).

Presumably, if they didn't have the power problem as well, they'd keep the mission going on S-band.

Lots of good info at
http://ulysses-ops.jpl.esa.int/ulsfct/spac...ft/scframe.html

[tedstryk]

It's not very great achievement, Ulysses at last was launched in 1990. Pioneer 6, the first in a series of solar-orbiting satellites was launched December 16, 1965. Although the spacecraft have not been regularly tracked for science data return in recent years, a successful telemetry contact with Pioneer 6 was made on December 8, 2000 to celebrate 35 years of continuous operation since launch. As of March 15, 2006, Pioneer 6 is still described as "extant", and is the oldest operating space probe (if still operating).

Pioneer 6 is an incredibly simple spacecraft, operating in a relatively consistent thermal environment. Ulysses is far more complex and relies on a finite power source. The fact that it lasted all these years and is only now being killed by the natural decay of RTGs (or the side effects from that lack of power) is very remarkable. Plus, Ulysses could have been preserved longer if they elected to turn the instruments off, but what would be the point in that?

[robspace54]

Thermal Constraints of the Reaction Control Subsystem

From: http://ulysses-ops.jpl.esa.int/ulsfct//spa...ft/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

[tedstryk]

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.

[ugordan]

November 7, 2098 Ulysses will be kicked out of the Solar system by Jupiter's gravity. Spacecraft's final trajectory will be highly hyperbolic (eccentricity~1.42), so it will be travelling very fast and one day, thousands years from now, Ulysses will reach some star.

I'm wondering how accurate HORIZONS data can possibly be for such distant dates. There has to be a number of unmodelled factors affecting orbital evolution of the spacecraft that the system doesn't take into account such as solar radiation pressure, slow outgassing from the spacecraft, etc. These will, given enough time, measurably perturb the orbit and I'm wondering what the real flyby distance and slingshot effect will be in 2098. Even tiny perturbations now can lead to large deviations in the future predicted passes.

I wouldn't put my hand into the fire and say Ulysses is heading out of the solar system, let alone heading out on a highly hyperbolic trajectory. Move the closest approach point to Jupiter by a million km in one direction and it could end up being decelerated by Jupiter instead.

EDIT: To give a sense of what I'm talking about, consider Jupiter's orbital velocity is 13 km/s and so it needs some 21 hours to cross a million kilometers. If Ulysses is early in its orbit by a mere 20 hours at the time of the 2098 flyby, the outcome could be radically different. A 20 hour cumulative in 90 years is really not much, especially since weak forces like light pressure tend to not change orbits much, but change their circumference a bit, which then brings timing differences that accumulate over time.

[tedstryk]

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.

[IM4]

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:

CODE

          Date (CT)        Body   CA Dist   Vrel
  ----------------------  -----  --------  ------
albedo=0 :
  A.D. 2098 Nov 08.19535  Juptr  0.009333  19.193

albedo=1 :
  A.D. 2098 Nov 08.71105  Juptr  0.014856  17.347

[robspace54]

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

[mcaplinger]

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."

[Mongo]

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

[elakdawalla]

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

[Paolo]

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"

[dilo]

fatti non foste a viver come bruti,
ma per seguir virtute e canoscenza".

Thanks for the info, Paolo!

[jamescanvin]

Looks like news regarding the death of Ulysses may have been a little premature.

http://www.spaceflightnow.com/news/n0804/15ulysses/

Scientists continue to extract bits of data trickling to Earth from the Ulysses solar probe as ground controllers employ new strategies to extend the life of the 17-year-old spacecraft, including a "long shot" plan to put the observatory in hibernation until the sun's activity reaches its next peak in 2013.

[GravityWaves]

After more than 17 years relentlessly exploring the effects of solar activity on the space that surrounds us, the Ulysses mission is now approaching its end.

[Paolo]

From the "programmes in progress" section of the latest ESA bulletin

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.

[Paolo]

Today at ESA Headquarters, the Ulysses Legacy press conference
http://www.esa.int/esaSC/SEMPEQUG3HF_index_0_ov.html

[robspace54]

Today is June 30th, so folks, say goodbye to old Ulysses, he's heading home at last... End-of-Mission July 1st, 2008.

Rob

[tedstryk]

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 nominal date, although tracking is still scheduled through the middle of the month (basically, this is as long as they figured fuel-bleeding might keep the hydrazine lines from freezing). A major science blow occurred at the end of May, when it reached a point at which it could only send data to the 70 meter antennae at 512bps. This is significant because the tape recorder plays at 1024bps at its slowest, meaning that Ulysses can only send data in real time now. Back during the 2003-2004 Jupiter Distant Encounter, the tape recorder was turned off for about three months so that it could operate all instruments at the same time (as opposed to power sharing, which it needed to do when far from the sun, since during the recent perihelion it could shut its heaters off and get the same effect). However, this required 24/7 DSN coverage, which, given the Jovian Science (a highlight was the additional data about dust streams from Io) that was being done, was worth it. However, at 512 bps (and soon to drop below that), it would be hard to justify constant coverage.

[nprev]

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

[ynyralmaen]

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!

[Rakhir]

Ulysses hanging on valiantly
http://www.esa.int/esaCP/SEMKWKSHKHF_index_0.html

[ustrax]

Humm...changes in the solar system?...any idea of what kind of changes we might be talking about here?...
Guess we'll have more details tomorrow...

[tanjent]

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.

[ustrax]

I'm starting to get the chills...Can it be related to this?...

[Del Palmer]

Don't fret, a new sunspot just appeared today.

[Del Palmer]

Ulysses 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.

[SolarSystemRubbl...]

Ulysses 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.

Even though most of the questions at the audio conference had to do with the earth's climate.

sigh....

[Guest_Sunspot_*]

Even though most of the questions at the audio conference had to do with the earth's climate.

sigh....

I wonder what it does mean for the climate...... clearly something unusual is going on.

[imipak]

Climatology's been ruled off-topic for UMSF I'm afraid. For alternative forums, you may find this search of interest (or not )

[Paolo]

There are status updates on Ulysses at http://ulysses-ops.jpl.esa.int/ulsfct/the_..._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.

[Paolo]

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

[elakdawalla]

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...

[tedstryk]

I would love it if it picked up one last comet tail!

[G0DXS]

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 ...

[robspace54]

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

Attached thumbnail(s)

 

[dmuller]

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.

[dmuller]

From the mission ops blog:

UTC Timestamp: 29-Jun-2009 21:00
Received notification that DSS-14 (Goldstone 70m ground station) has been declared RED. We are scrambling to rearrange the command sequences for the final day of operations which are due to be transmitted during our scheduled pass over DSS-14 which is supposed to start tomorrow at 00:00 UTC. We are also persuing alternate coverage over the 34m network, in which case the command sequences will be transmitted in the blind, i.e. without telemetry verification.

[Astro0]

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!

[ustrax]

"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

[dmuller]

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

[cbcnasa]

Thank you and farewell Ulysses