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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?
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
QUOTE (deglr6328 @ Sep 27 2005, 08:22 PM)
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!......... wacko.gif
tfisher
QUOTE (deglr6328 @ Oct 9 2005, 02:01 PM)
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!......... wacko.gif
*


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
QUOTE (Rakhir @ Nov 17 2006, 09:47 AM) *
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
QUOTE (remcook @ Jan 29 2007, 03:52 PM) *
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! wink.gif
remcook
ah I see now.
ustrax
There goes Ulysses...again... smile.gif

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!"
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... cool.gif

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
QUOTE (nprev @ Feb 11 2007, 09:17 PM) *
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
QUOTE (nprev @ Feb 11 2007, 03:17 PM) *
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... cool.gif

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
QUOTE (Jeff7 @ Feb 12 2007, 10:36 PM) *
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
QUOTE (centsworth_II @ Feb 12 2007, 10:56 PM) *
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. wink.gif


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
QUOTE (dvandorn @ Feb 21 2007, 03:43 PM) *
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... sad.gif
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
QUOTE (dvandorn @ Feb 21 2007, 10:43 AM) *
...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
QUOTE (ustrax @ Feb 7 2007, 02:47 PM) *
"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
QUOTE (Paolo @ Feb 11 2007, 08:44 PM) *
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! smile.gif 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
QUOTE (edstrick @ Feb 24 2008, 12:28 AM) *
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
QUOTE (peter59 @ Feb 23 2008, 09:14 AM) *
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
QUOTE (IM4 @ Feb 23 2008, 02:23 PM) *
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
QUOTE (Paolo @ Mar 15 2008, 10:31 PM) *
fatti non foste a viver come bruti,
ma per seguir virtute e canoscenza".


Thanks for the info, Paolo! smile.gif
jamescanvin
Looks like news regarding the death of Ulysses may have been a little premature. smile.gif

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

QUOTE
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.


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