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Ham Satellite Suffers Failures, Is Silent
"We may have to wait until after Christmas for another reset. Controllers have not transmitted a hard reset command yet, which would work even with the flight computer crashed, as they wish to explore other options. The satellite would automaticaly cycle through a number of frequencies and antennas if it does not get any commands for 10 orbits, and controllers hope to re-establish control as this happens. A hard reset could delay that option.
"The satellite waited several years for launch due to Arianne 5's early failures and a revised accelleration profile for the booster that required a redisign of the satellite frame to take additional stress. Aging may have effected components such as the fuel valves. Telemetry stopped suddenly during work on the 400 Newton kick motor, leading to speculation that the satellite may have suffered physical damage, but NORAD radar profiles indicate that it has not exploded.
Problems with Phase 3-D are bad news for hams, who raised $1 Million for the satellite, the 40th in the series of Amateur satellites launched since 1962. Phase 3-D has been criticized for pu ting too many eggs in one basket, unlike other small ham satellites built on a low budget and more easily launched as hitch-hikers with other payloads than the multi-ton Phase 3-D.
"The core development team urges patience. The satellite is in a stable orbit in one piece, just where it is expected to be, as confirmed by NORAD. They can take lots of time to debug it where it is, and hope to restore its functionality.
"For bulletins, see the AMSAT web site.
"A number of other ham satellites remain operational, and astronauts are currently using a ham station on the International Space Station to speak with people on the ground."
A hard reset would be physically turning the system off and on again.
ctrl-alt-delete is a soft reset.
How quickly do bits get corrupted? I would have thought that with a load of error correction and a device continually fixing things up again would grant you quite a bit of stability© Really there isn't anything preventing storing 128 bits¥or more for every byte© If any go wrong they should be correctable before the byte becomes unrecoverable© The only thing that this wouldn't help is if bursts of radiation take out all of the data very quickly, Is this what happens?
I would also have though that the same should go for processors© If you sent up a satelite chock full of FPGA's ¥presubably with every cell containing a lot of redundancy on their state memory you could make work arounds for many failures, lik say a NASA Screwdriver going through one of the PCBs©
How well can the radiation conditions of space be replicated on earth for testing tis sort of thing?
-- That which does not kill us has made its last mistake.
Linux does this too. I've had various linux installations lock up hard. It's generally due to bad hardware, or a hardware conflict. This is true on windows as well, however. Also, linux may kernel panic (I've had my FTP/shell box do this twice since I installed it three weeks or so ago) and if you're in X, it may look like the box has just hung, depending on your video card.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
My understanding is that they also have the equivalent of the "big red power button" or "control-alt-delete", which they haven't even started to try yet.
Plus, when you increase the amount of metal shielding around electronics, you start to get a small amount of radiation from *that*.
"Beware of he who would deny you access to information, for in his heart, he dreams himself your master."
In 2000. I guess you haven't seen this! 1.8 MHz through 450 MHz, all modes, self-contained AA batteries, and OK it's got a shoulder strap, but it's a handheld.
And no, I haven't missed articles on working satellites via FM. That's what I was talking about.
People can set their own challenge levels, and if they are interested they work from low to high. Having an easy satellite mode would have been a great starter for beginners and especially young people. You know young people, they look like other hams, but aren't bald with a limp :-)
People gave me the same argument about packet in the 80's, which came down to where's the sport in that? Not everybody is into Amateur Radio for the sport.
Thanks
Bruce
Bruce Perens.
They should have consulted with Pizza Hut for better funding, like the Russians did.
------
Let me give you the lowdown
I've got $20 that says that MIR hits Earth before this thing does! Any takers?
------
Let me give you the lowdown
The RAM corruption on the experimental backup flight computer is a normal feature until the EDAC software "scrubbing" routine is enabled. This constantly scans RAM for errors and corrects them before they grow too large to be correctible. That software has not been loaded yet.
The 145.898 beacon was not damaged, a 440 MHz one was. The 145.898 beacon runs from the backup flight computer while the 440 MHz one runs from the primary one. That's why the backup flight computer could cause a loss of telemetry.
There have been a good deal more than 40 Amateur satellites, only the ones that actually reached orbit and transmitted get numbers, and there are Amateur satellites outside of this numbering series.
Insiders tell me to relax, have patience, and that it is really jumping the gun to think the bird is lost.
Thanks
Bruce
Bruce Perens.
I was with you until the "Maybe the jews deserved to be cooked,..." comment. Personally I don't care if you're fat, disabled and gay, but the "jews deserved to be cooked"? Please. I'm not even Jewish and I'm offended.
Bruce?
Bruce Perens.
Clever little script kiddies here have either crackerjacked my password, or have hacked /. itself. They were even congratulating themselves on how clever this was, on a thread I'd posted to a day ago.
:)
It's been changed, and shall be changed fairly often, too. Maybe this will help. For those who've read these, you *might* know me well enough to realize that my spelling is darned good, and that I've never been raped, nor have I ever "had" a man, period.
As for the Jews, that's too sick to comment on. Perhaps I should run this past my ex-boss, one of the nicest men I've ever known, himself Jewish? He may get a mild giggle from it. I'm sure my partner, herself Jewish, would be amazed
Lemon curry?
Apparently, there are a great many of us who neither care for, nor wish to be a part of the "action" on Slashdot, which these days has turned into something i'd imagine closer in resemblance to a gay bar than a channel for geeks to use and enjoy. [....] PS.. Be sure and snicker in amusement as an endless stream of kiddies and tyrant moderators take their time to write out a few lovable responses to this post--After all, encouraging geeks to go elsewhere is no fun for them--They'll have nobody to push around! But incase they do, be sure to note their names..Look them up with a handy /whois command next time
you're in IRC and decide for yourself the answer to the topic. The rest
of us are already sadly aware of the answer.
Nope, ctrl-alt-delete is soft....
We at the Great News Network present the official transcript from the room where the satellite was being constructed:
Bubba: "Hey Jeb, you got that there SIMM that I need fer the new sat?"
Jeb: "Yeah Bubba, Ah got 'er right here... CATCH!"
(throws 8 MB 30 pin SIMM to Bubba, it bounces off of Bubba's head and lands in a cup of cola)
Bubba: "Awwww, dang, what are we gonna do now?! The dern thing fell in the pop and sunk in!"
(Jeb picks up the cup and pours the cola out to retrieve the SIMM)
Jeb: "Just keep quiet about this, maybe none of them controllers will notice, here, get me that there can of WD-40 to clean this pop up..."
"Titanic was 3hr and 17min long. They could have lost 3hr and 17min from that."
IBM had PL/1, with syntax worse than JOSS,
And everywhere the language went, it was a total loss...
Sorry, maybe I need more sleep, but that's the first thing that came to mind when I saw "Ham Satellite Suffers Failures"... Either that, or more caffeine...
Just because you can mod me down, doesn't mean you're right. Shoes for industry!
Ask NASA, other space agency or people in university labs that research this stuff about proper radiation shielding for processors?
Actually, NASA and most other space agencies utilize data collected on Amateur satellites. IOW, a lot of the research comes from the Amateur community.
A Ham satellite might launch with five different types of RAM, each hardened using five different new techniques. The hardened RAM might be donated by various agencies. They get to test their RAM-hardening techniques cheap. The Amateur community gets free space-hardened RAM in exchange for the risk posed by using something not quite tried-and-true.
I, too, wish them luck. I might even blow the dust off my IC-970H and 22C/40CX!
de Gus 8P6SM (formerly active on AO10, AO13, AO16, FO20, KO23, AO27)
Several years ago I worked for an "engineering service contractor" for NASA, and had the opportunity to design the sensor electronics for a space-based sun-staring telescope, called Solar X-ray Imager. The task would not have been excessively difficult except that the radiation levels expected were quite high, and we had to design it to be very radiation resistant. This proved to be very expensive to do.
For certain electronic functions, there are radiation hardened integrated circuits. We used a set of CMOS devices manufactured by Harris (now Intersil) which are manufactured using a silicon-on-sapphire technology which makes them tough indeed. (The manufacturer claimed that they were radiation resistant up to "strategic levels" - to run through massive radiation doses and never glitch...) While they were very good parts, their cost was incredible. They were getting US$ 225 for a single 75hc00 equivalent device which usually costs 25 cents. Processors and memories had prices that were proportionally worse. Nobody but government bodies with the power of taxation can afford these things.
The other method of achieving radiation hardness is shielding. In our case, we had to use this in addition to the radiation hardened integrated circuits, because the telescope sensor itself was not radiation hardened (otherwise it would not have been able to see light either!) The shielding we used was made from tantalum, machined in shapes to cover the sensitive parts. Now tantalum is not inexpensive, it does not machine well, and is heavy. The weight is the limiting factor, since whatever you use you have to launch into space, and the cost per kg is very high. Shielding which is sufficient is also too heavy to launch on a secondary payload.
My thoughts? Amsat did the best they could within the budget, and the budget (raised from donations) did not provide enough money to use the premium radiation hardened parts everywhere.
Too bad...
73 de W4TI
Free the mallocs!
This made me curious as to the major storage medium being used in space?
...its RAM corrupted every 1 or 2 days in orbit as it crosses radiation belts... because this single-bit error mode is common and expected. I'm not really current but I don't think any Amateur birds fly with hard disks on board...
:)
RAM-disks are common. Cosmic rays and gamma particles cause single-bit errors every few hours, which is why they use 11-bit RAM for EEC and run a software program that "washes" the RAM continually. I don't think this is what they mean when they say
Is heavy shielding a solution for this?
Heavy is not a good word when you are trying to get something into orbit!
de Gus 8P6SM (formerly active on AO10, AO13, AO16, FO20, KO23, AO27)
How well can the radiation conditions of space be replicated on earth for testing tis sort of thing?
You use an X-ray machine, a van de Graf generator, a vaccumm chamber, and so on. It doesn't get you all of the way there, but it can give you some data.
Thanks
Bruce
Bruce Perens.
Where the hell are you getting this ESA stuff from?
All they did was sell space on their rocket - The launch itself went perfectly. No evidence of government screwups there.
The satellite was designed, built, and the launch paid for with private funding. AMSAT is non-profit, but non-profit != government!
retrorocket.o not found, launch anyway?
No crackerjack needed, check the user numbers ... Gee, that's lame :) 17812 is me, any other number is not-me. Simply little boys trying to have fun. :)
Lemon curry?
Hey, Bruce? There have been SSB handhelds around since at least the late 1980's. I distinctly remember a couple of 6- and 2-meter SSB handhelds put out by various manufacturers - and they *were* handhelds, about the size of a dual bander today.
-- Ed Carp, N7EKG erc@pobox.com PGP KeyID: 0x0BD32C9B What I'm up to: http://intuitives.mine.nu
As I read this article (at +2, no parent -- seems reasonable in most discussions), I'm distraught by the number of posts being displayed by Bruce Perens. Sure, he's (appearently) a smart guy who knows at least enough about the subject to author the article, but why are 10 out of 22 >+2 posts from him?
Counting the article itself as 1, that's -half- of the displayed posts, which is just silly.
Either the moderators are favoring Bruce's commentary (which is typically useful, informative, and insightful -- though not without context), or Bruce is using his +1 bonus on every post (which is -not- needed on a three-line message, no matter what it contains).
As it is, some of Bruce's replies are without displayed parent posts, and in (at least) one instance he appears to have replied to himself (which means there's at least two <+2 posts which need attention).
Just a random musing...
Kid-proof tablet..
Bruce has explained that the critical onboard computer is rad-hard. The one that has the ram corruption is an experimental unit. The control team was planning on uploading error detection and correction (EDAC) code to deal with the ram corruption.
Hamsats spend their money where they have to and use clever design to get workarounds where they need it. And we take more risks than the commercial and scientific folks.
Eyesat/AO-27 (launced in 1993) uses a NEC V50 CPU with EDAC code for a 16MB ram disk. The only rad-hard chips were used for the boot roms, so a reset (either CPU crash or from a reset command) is unlikely to fail. As I recall, those few chips cost a fair percentage of the rest of the satellite's computer.
I might add that the AMSAT designers are VERY experienced with the space environment. Many work in space-related industries. The primary computer on AO-40 has a design history including two successful predecessors (AO-10, 13). They know what they are doing.
KA1LM
To find out more, go to http://www.amsat.org.
what they do put windows on it.... this stuff sounds familir http://members.home.net/jessezack/images/320.gif
kinda rediculus if you aske me..
As a ham who's used satellites before, this is awful :( I hope they figure it out soon.
Lemon curry?
Just one question. What is the purpose of this satellite? Are people with ham radios supposed to be able to brodacast back and forth to it or something? I guess I am just out of the loop on this one.
What's a Sig???
A backup flight computer, itself an experiment to see if the CPU would be radiation-hard enough to survive, has its RAM corrupted every 1 or 2 days in orbit as it crosses radiation belts and currently is not set up to reboot automaticaly.
I don't want to sound arrogant here, but couldn't they either:
1. Put a radiation hardened processor instead just like everybody does or...
2. Ask NASA, other space agency or people in university labs that research this stuff about proper radiation shielding for processors? [I understand this option may be more complicated than it sounds]
In any case, I wish them luck.
Flavio
Google, Yahoo, Metacrawler, etc. are all more efficient then asking every time someone else to explain it for you.
ps Also check the links in the article itself.
I don't read ACs: If a post isn't worth so much as a nom de plume to its author then I wont bother either.
"Controllers have not transmitted a hard reset command yet, which would work even with the flight computer crashed,"
Is that like hiting ctrl-alt-delte?
Have you ever had one of those days when nothing goes right for you?
I think there's at least 50 satellites up there for grabs. Pick your favorite color.
Launching stuff into space is a risky and difficult process. All these problems are why NASA used to build triply-redundant probes (Mariners, Voyagers, etc) and then send two or three of them.
Anyone who's ever programmed on a REAL production system will attest to the fact that it's the last few obscure bugs that are the most difficult to find. The difference between a 99.99% bug-free product and a 100% bug free one is enormous.
The rad-hard CPU of choice for spaceborne equipment is the 1802. Remember the RCA COSMAC personal computer of long ago? I think they have this in silicon-on-sapphire. There are a small number of satellite hackers who still practice 1802 assembler at this late date. It should suffice to say that nobody uses this CPU for anything else any longer. So, an experiment with a modern CPU was very desirable. It looks like the problem might not be in the CPU.
Thanks
Bruce
Bruce Perens.
I can actually answer some of this. I used to work at JPL on spacecraft computers, back when I was a EE student. I did stuff like writing bootstrap code in assembler that was particular to the custom chips that comprised the computer. I also designed PCBs for the test platform.
Space is a brutal environment. Even out in the deep black between the outer planets, there are a lot of gamma rays and charged particles that would play hell with a conventional computer. Spacecraft computers are built of relatively old-fashioned components, and they are made with a special radiation hardening process. There are no 1GHz CPUs in space. We don't really need them, either; the tasks performed by robotic spacecraft are pretty simple, compared to say running Windows.
Shielding isn't the answer. Imagine a metal box around a computer. Now imagine a proton or some other relatively heavy charged particle is fired into the metal. The particle can hit an atomic nucleus and shatter it, flinging MORE particles into the hapless computer. Bad news. And shielding thick enough to protect against this is heavy, and that's bad for spacecraft too.
So they use simple, rugged components, that can usually resist a proton zipping through them. And for the times when a bit gets flipped by a particle -- this is called a Single Event Upset or SEU -- there is a TON of error correction & detection bits allocated in these computers. The system I worked on, which is the computer in the Cassini craft, used a modified Hamming code. I think that almost 1/2 the bits in every 16-bit word were allocated to EDAC.
Unfortunately I do not remember the details of how you fab a chip to be radiation resistant. Some special substrate, special transistors... I'm sure you can Google for it.
But yes, this is a large number of initial failures for a ham satellite. Most of them are much simpler. But all of them have things break and they patch around it and go on using the bird. The same is true for commercial communications satellites.
Thanks
Bruce
Bruce Perens.
A backup flight computer without a watchdog timer?
I believe there is a watchdog timer. It triggers if there is no traffic on the telecommand receiver(s) for ten orbits. Since it's a deep-space bird, AO40 has a long orbital period (mean motion 1.268-ish orbits/day). The watchdog timer will not time out for nearly eight days.
de Gus 8P6SM (formerly active on AO10, AO13, AO16, FO20, KO23, AO27)
My understanding is the controllers had not yet uploaded EDAC code to the IHU-2 computer when the telemetry failure ocurred. That would have solved the RAM corruption problem. And maybe alleviated whatever happened, as they were having problems with the default 70cm telemetry beacon from IHU-1 and were using IHU-2 to activate the 2M beacon.
KA1LM
It is premature to conclude that the spacecraft has failed. This has not been determined and there several steps yet to be undertaken in a recovery process. This is just one, albeit the most complex so far, of a great many "open source" satellite projects. Space projects are a very complex undertaking, and even tougher when done by volunteers on donated $ contributions.
AMSAT has announced that it will put together a (volunteer) inquiry into what happened, during the next few weeks. There are many speculations as to "what went wrong", but very few based on actual data. It remains entirely possible that controllers will regain control by issuing a hard reset in the near future. After the inquiry is completed, and after all system restarts have been completed, then it is time to make plans for the future.
Ed, KF7VY
http://hamradio-online.com
RIAA and M$ have stated, "We can not allow hacker ham radio operators to steal our intellectual property." They will allow AMSAT Corp access again for 26 Million Dollars for a 1 year license fee.
They also want to inspect the satellite HD contents because the Napster server says they have a MP3 of Rocket man and a AVI video of the Moon Launch on the HD
In a related story the FBI has raided the ARRL ham radio HQ looking for antennas and radios that could be used to listen to frequencies, they also confiscated secret PSK31 transmitters that could be used by spies to send signals to spy agencies.
Also discovered was a secret world wide system to track people, cars, boats and planes without the knowledge of the passengers. The secret program, called APRS, violates USC 3, 21 and Janet Reno indicated today that all licensed ham radio operators will be investigated. You may remember that the Branch Davidians used ham radio during the seige at Waco.
Will the last company to abandon Linux please turn off the lights??!
I find them fascinating. I'm surprised we don't see a real investigation about them - or maybe not, considering what they probably are. :-)
The revolution will NOT be televised.
What's stopping you? Get the money and launch yer ass into orbit.
The role of government in space should be ZILCH. If you think otherwise, look at its fucking track record.
You mean the track record that put us on the moon THIRTY YEARS AGO when most countries were happy to have running water? Oh yeah, I'm sure we would've landed on the moon if it was left to companies who have to keep Wall St. happy on a quarterly basis.
If the government hadn't had its hands in there we would have been on the moon five years earlier.
If you turn off Rush Limbaugh for a few minutes and check your history books or talk to some of the people involved you'll quickly see that statement is ridiculous. I followed the space program quite closely in the sixties, and we were lucky any of that stuff worked. Who do you think does the work? Private contractors. If they could have done it faster, commercially, and made money at it they would have. They didn't.
The revolution will NOT be televised.
It is only "open source" if you define "open source" as "done by enthousiasts in their spare time". I don't think the "open source" folks will accept that definition... While some design information, like block diagrams, is available in various scattered papers submitted to amateur satellite conferences, there is no complete documentation available to the world. No circuit diagrams, technical drawings, let alone sourcecode of the software running on the IHUs (the onboard computers). Some people already indicated it would have been good if that was the case (because of peer review possibility). The reason for not doing it seems to primarily the extra work it would be for the core design, construction & control team to document everything well enough to put it on a website. (probably this could be solved by finding a volunteer who can do most of this task without too much involvement from heavily burdened people)
Actually, not even ESA is involved in this. Ok, they are involved in the design of the rocket, but not in the launch. Ariane launches are sold and managed by Arianespace (http://www.arianespace.com/), a commercial company.
and let responsible corporate entities do what they do best
What would that be, gouge their customers and dump toxic waste in the local waterway?
"responsible corporate entities" is a bit like military intelligence - they both DO exist, but only in very small quantities.
Oh yeah, I'd feel much better if Microsoft was running the space program. No slip-ups, cover-ups or nefarious business practices there. No suh.
The revolution will NOT be televised.
If you're a developer like me, you definitely realize the technical challenge of developing hardware and software for which you cannot explore all test cases, and cannot test under the real conditions at all, until the thing is sent off in space and you cannot do much about it if something important breaks.
There is a lot to learn from such a project, about software/hardware fault tolerance. Is there anybody from the project reading this (Bruce, do you know who to contact ?) who could give a basic explanation of the produces involved?
I know about error-correction for RAM, watchdog timers, duplicate hardware, and self-contained communication code that you can use to get control back. This is pretty classical stuff for the domain I work in (embedded systems); but this is way more impressive.
I'd love to have someone from the project give a rundown of their procedures, even if not all goes as expected - we can learn a lot from it.
--
Emmanuel
Penguins have lots of non-volatile RAM. The Linux Pimp
--It's Pimptastic!--
I work for a telemetry company as a programmer (www.veridiansystems.com), and I can tell you our bit syncs will lock on just about any signal. I'm not sure what these people are using, I pretty sure it's not our stuff, but with the current state of technology in telemetry, I can say that satelite is as good as dead.
In another somewhat unrelated note, our company has been in the process of porting some of our "Front End processing" technology to Linux. This is where the real telemetry number chrunching goes on. We are looking to replace Origin 2000 servers with little x86 boxes....
actually, read the article and check the link out. the satellite was built by amsat and launched on an ESA rocket. nothing to do with NASA. wake up.
So this is kind of an open source satellite, isn't it? At least it is clearly an effort of multiple people donating their own time to a project. And here is a result - a piece of crap in space, useless and broken.
Next time you try to point fingers at NASA look this up and shut up.
Um, this bird was NOT designed, nor built, by NASA. It was designed and built by a corporation, of radio amateurs from all over the world. They had the idea, they raised the money, they built it, tested it, and paid to launch it.
:(
Don't pin this one on NASA. The hams decided they didn't really need rad-hardened hardware and multiple redundancies. They're learning the hard way, I fear
Lemon curry?
It is common for subsystems to fail on satellites. That is why they usually have redundant systems for critical functions. On scientific satellites, there may be many experiment packages on the satellite. You normally don't hear about one of them failing, unless you have an interest in that experiment and read the status reports.
Mea navis aericumbens anguillis abundat
A backup flight computer without a watchdog timer? Couldn't they rip out out of a Pac-Man machine and use it?
Whoever just moderated this comment down to a zero, you are EXACTLY the type of idiot I'm talking about.
AMSAT-OSCAR 40 Status report of December 13, 2000 Nearly four weeks have now passed since the launch, and there are some good things and some bad things to report. As you all know, immediately after separation, we could not receive the 70 cm transmitter. Consequently we programmed IHU-2 to act as repeater and use the 2m middle beacon instead as our main downlink. In addition the two S-band transmitters have been operated occasionally, but the geometry within the orbit must be right to have the antennas point into the general direction of earth. This limits the use we can make of S-band. The main activity so far for the command stations was to learn to fly the s/c and to prepare it for the first burn with the 400 N motor. This required a reorientation - the s/c must point opposite to the perigee orbital speed vector - and a spin-up to about 9 rpm. In view of this ongoing work, it was decided to postpone the analysis of the problem with the 70cm Tx to a time after the first burn. The reorientation of the spacecraft turned out to be more time-consuming than initially assumed. We had two problems to solve: 1. As we get to our firing attitude, the geometry is very poor for producing direction changes of the spin-vector. The magnetic field of the earth is nearly perpendicular to the spin axis meaning that we can change rpm easily, but not direction. It turned out that rounding errors in the software of the IHU were in the same order of magnitude as the desired spin-change. Thus reliable control was not possible. But careful tweaking of the parameters used in the IHU finally enabled us to solve this problem. 2. The geometry is also poor in terms of attitude determination by our sensors with earth and sun viewed almost from the same direction. In fact for a certain time the earth sensor was blinded by the sun and delivered no useful data at all. But here the YACE camera in conjunction with the IHU-2 came in very handy. By taking pictures of the earth at strategic times we could use the YACE as another earth-sensor looking to the top of the s/c. It gave us badly needed additional data. The IHU-2 played a vital role in processing and storing these pictures. Unfortunately the IHU-2 turned out not to be so reliable as the IHU-1; every one or two days it crashes. This results in the beacon transmitting only a weak carrier, but no modulation, until the IHU-2 is manually reset from the ground. So far this posed no real problem, but it is a nuisance. Also we have now some data of how the memory is corrupted by radiation. Eventually we hope to install additional software in the IHU-2 which allows us to avoid or at least automatically recover from these crashes. But this has to wait until things get a bit quieter. Until this time we will have to live with the IHU-2 crashes, which seem to be caused by hard radiation and typically occur, when the s/c comes out of perigee and enters the radiation belts again. Around Sunday Dec. 10 we had finally reached the proper orientation and spin for the first 400 N motor burn to take us to 50000 km apogee altitude. After reviewing the various constraints it was decided to execute this burn on Monday, Dec. 11 in the perigee of orbit 50/51. The necessary program was uploaded - this is an automatic sequence since the s/c is at this time at the equator with only 600 km altitude. Thus no command stations can be in contact with the satellite at the time of the burn. So perigee 50/51 came and went - but the burn did not take place. The stored telemetry was analysed and it was found that the sequencer went through all the necessary steps, but no helium pressure was built up and consequently the burn did not take place. (It takes helium pressure to open the fuel-valves.) On Monday Dec. 11 the situation was investigated and it was found that the pressurisation command was not resulting in any action. Initially the investigation concentrated on a software discrepancy, which existed between the software to test the system in Kourou and the one used in flight. But it was found that this probably was not the cause - the valve(s) simply refused to open. We had such a problem before during the test phase of the s/c, and one of the helium valves was repaired as a consequence. All the indications are that we ran again into this type of problem - which may be caused by the age of the components we are using. We then executed multiple open and close commands, which eventually got the helium flowing. But it was also noted that the helium flow was almost an order of magnitude less than required. Still we build up pressure in the tank to nominal and then programmed the s/c to perform the burn on Monday evening. This time the burn started properly, but there were some anomalies in the telemetry indicating that the burn did not stop at the programmed time but lasted about 3 minutes longer. Thus we achieve an orbit with about 60,000 km apogee altitude. For our ultimate plans this is no problem, we would have used the electric propulsion anyway to further increase the apogee. James Miller had written a data collection program for IHU-2, thus we have a very detailed account of all the events of this burn. A detailed analysis is under way, but we have already some first indications of the nature of the problem and also possible ways to cure it or at least to cope with it, provided that the motor was not damaged by this event. During the next days we will investigate this matter in detail. If we have a real problem with the 400 N propulsion system, we may need to change our strategy for achieving a useful final orbit. But it may also mean only that we have to observe a number of boundary conditions during the following burns and that the situation may have no impact on the mission goals. For the next days no attitude changes are planned, thus we will be able to start to investigate the problem with the 70cm TX. During these tests we will find out if we can operationally plan on using the 70cm TX or not. So we are living exiting times. Finally we would like to express our compliments and our appreciation to the command stations for the superb job they are doing. Each day they are facing new difficulties requiring a very large amount of time and dedication. They are doing a SUPER job
I'm not stupid, I'm disabled. Get it straight.
I gave up Catholicism for Lent
That is an amazingly high number of failures for something like this.
I always percieved space vehicles to be perfect and assumed that nothing every broke on them, but simply wore out by design
Is is normal to have so many things fail on a space vehicle? Does this kind of thing always happen, but doesn't get mentioned?
--- I hate my sig