Slashdot Mirror
NASA Reconnects With 'Lost' STEREO-B Satellite (businessinsider.com)
NASA lost contact with its STEREO-B spacecraft twenty-two months ago during a routine 72-hour test. On Sunday, the spacecraft reconnected with NASA roughly 189 million miles away from Earth. While that would seem like a cause for celebration, "the very hard and scary work is just the beginning, says Stereo project scientist Joe Gurman, as the agency has to turn on the computer to learn more about the current state of the spacecraft -- a process that may make the craft lose contact with them again. Slashdot user bongey writes: NASA may have only two minutes or less to fix a STEREO-B satellite before the computer causes it to lose contact again. NASA lost contact with their STEREO-B satellite nearly twenty-two months ago when performing a routine test. NASA scientists are afraid to turn on the computer at this point because it may cause them to lose contact again. A more detailed technical summary can be found here. "We have something like two minutes between when STEREO-B receives the command to boot up one of its computers and when it starts doing what we don't want it to do," Gurman said. Business Insider writes, "Making matters worse, it takes about 20 seconds to send commands to the spacecraft -- a data rate that makes a dial-up modem seem lightning fast."
I'm guessing that the throughput is slow enough that sending a command to the spacecraft takes 20 seconds of tx time - e.g. it might take 10 bytes to send a command and are getting a data rate of 4 bits per second.
Latency isn't as much of an issue in this case, as once they send the wake up command, they can have the other commands in flight on their way to the satellite, but it's going to stop listening and do something they don't want it to do ~2 minutes after it gets the wakeup command - likely due to a fault with a sleep timer or similar.
Specialist Mac support for creative pros, Melbourne
This is the kind of stuff that is truly exciting to an engineer interested in space. A satellite in an uncontrolled spin due to a bad inertial unit, without enough power in its batteries to transmit at full power, a network of deep space communications satellites colliding signals to create constructive interference to boost communications, a plan to point several radio telescopes towards it in the hope to hear something, sweeping the sky with different frequencies and if all else fails point the Hubble at it.
Combined with the short time window to make things work the only thing missing here is Matt Damon and you got yourself a summer blockbuster.
NASA lost contact with their STEREO-B satellite nearly twenty-two months ago when performing a routine test. NASA scientists are afraid to turn on the computer at this point because it may cause them to lose contact again.
What's the point of being able to talk to it if they can't turn it on and actually do stuff with it?
If they thought they lost it 22 months ago, they have nothing further to lose if it goes away again now.
With no javascript the page is black-on-black. Congrats for leading edge tech.
You have to be trolling.
Knowledge of what the Sun is doing is essential for anything we do in space, including studying the weather and climate, because solar radiation is dangerous to equipment as well as people. And down here on earth - someday there is going to be a solar storm such as happened in 1859, which set telegraph cables sparking across the planet. Today, such a thing would fry our phone and electric systems if we can't predict it with the certainty needed to, literally, shut down and disconnect our electricity and copper communication networks while it passes by.
And of course, while it is CO and methane that are driving climate change, the heat it traps comes from the Sun, so good knowledge of what the Sun is doing is needed to understand our measurements of temperature.
Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
F2 F2 F2 F2 F2 F2 F2 F2 F2 F2 F2 F2
Dammit!
TFA quoted one of the NASA engineers "If we turn on the computer, which is the only way we can get insight into the current state of the spacecraft ... what got us into this mess in the first place could turn back on again."
It seems that in order to really know what commands to send, they first need to query some data from the computer. So something like:
Query the most interesting parameter. 20 seconds to rx the reply. (1:40 remaining)
Decide what to query at next. 10 seconds to think and decide. (1:30 remaining).
Decide on a fix and get it sent off, 1 minute. (30 seconds remaining).
Commands take 20 seconds to reach the spacecraft (10 seconds remaining).
Craft executes the instructions, changing its orientation or whatever is required.
Unpucker.
They couldn't find the goddam recovery CD.
View the page source. It seems that stalking analytics code from iPerceptions and Google is the reason their forcing Javascript use.
https://www.google.com/analyti...
When are they ever going to implement the AE-36 units??
I blame systemd.
More likely, it takes about 20 seconds to boot up, at which point it runs the same routine that caused the problem in the first place.
But how do you really feel?
Wanna buy a shirt?
https://www.redbubble.com/people/stealthfinger/shop?asc=u
They couldn't find the goddam recovery CD.
Isn't the recovery disc on voyager?
Wanna buy a shirt?
https://www.redbubble.com/people/stealthfinger/shop?asc=u
This is a definite improvement on the cows moo shit and the appy apps shit. Well done you.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Why is this even on Slashdot? It sounds like it belongs on the Missed Connections page of Craigslist or something like that?
First bandwidth. It's probably decreased with distance, signal strength, etc. Even Barker code fails at some point.
Then distance, my friend. Unavoidable latency. Not going to be able to respond before the darned thing has gone awry.
And there was probably a failsafe startup, but *it* failed...
I feel sorry for them, but it's a teaching moment also.
deleting the extra space after periods so i can stay relevant, yeah.
You're right. I interpreted that "20 seconds" as meaning 20 seconds delay. That would indicate a distance about 12-13 times as far as the moon. As you mentioned, the craft is actually roughly on the opposite side of earth's orbit, near where the earth will be in 5-6 months. That's a much further distance, about 16 minutes at the speed of light.
> most likely the result of the small bandwidth they can work with due to the computer not being booted up or something - because for example the "BIOS" can only receiver commands at 1kb/s or something
That, or since it's low on power, the data rate is much lower than max. (That's to be expected, over long distances, lower power signals need to be slower.)
The transceiver is capable of up to 427 Kbps or 720 Kbps, depending on the source you read.
http://stereo.gsfc.nasa.gov/im...
http://stereo.gsfc.nasa.gov/sp...
As you said, it's entirely possible that the main computer can do that data rate, but the IPMI/DRAC/ILO is far slower, or the lack of available power dictates a slow rate.
You are correct. 189 million miles (from TFA) is 17 light minutes. The STEREO satellites are positioned opposite Earth from the Sun http://stereo-ssc.nascom.nasa....
NB: The message above might reflect my opinion right now, but not necessarily tomorrow or next year.
No, its on Stereo A.
Can't they just switch it to "Stereo A"? I mean even my A/V receiver at home has that switch.
It must have been something you assimilated. . . .
No, the article specifically says that after it boots they have approximately 2 minutes before it goes into a fault condition
Specialist Mac support for creative pros, Melbourne
I wonder what it would be like running a CD mount on that IPMI...
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
I am impressed we can communicate with those sats so close in angle to the Sun. I would think the Sun would drown out the carrier frequencies and make locking onto the spacecraft's signals damn hard.
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?