Posted by
CmdrTaco
on from the congrats-from-the-news-nerds-to-the-nasa-nerds dept.
tvh2k writes "CNN reports that both the Mars Rovers Spirit and Opportunity are now both fully functional. Working on opposite sides of the red planet, they have begun analyzing rock and soil samples."
I guess the idea of a redundant rover is to make sure that errors are not a total loss. But it's nice to have both, especially since Opportunity seems to have found evidence of water. This has been really exciting to follow.
Re:Very good news
by
Dominic_Mazzoni
·
· Score: 3, Informative
That's a funny quote and all but I don't know if it's entirely true in this case. A lot of the cost involved was put towards getting the technology together and paying the people involved. Once one was built, the other one just required the same set of parts and a team to assemble and test it. No R&D costs were repeated.
While it's not exactly assembly line type savings, there is a reduced cost for building a duplicate of something that already has been built.
That's true, and FYI, they actually built three rovers, just in case there was an accident with one of them before launch.
Rover status updates
by
aurum42
·
· Score: 5, Informative
I've found this site very informative, with frequent rover status updates, links to images, NASA press releases and details of rover activities.
-- "The slave who knows his master's will and does not get ready...will be be beaten with many blows."Luke 12:47-48
Re:Erosion caused by water
by
Feyr
·
· Score: 4, Informative
the "source" you're looking for is usually the clouds (rain) AFAIK. though i'm no geologist, but i'm pretty sure of that
Re:Power leak
by
Tablizer
·
· Score: 5, Informative
So, is the power leakage on the Opportunity rover also fixed or are they just going to put up with a shorter lifespan of the machine?
My understanding is that it is still not resolved. Appearently the rovers can still work in the day with a dead (non-rechargable) battery, but the cold from lack of heaters eventually damages electronics. Thus, one way or another it will probably shorten the mission (assuming something else does not bust or dust-up first).
Re:if it can dust one thing, why not another
by
Thagg
·
· Score: 4, Informative
I have heard that it's really important that space probes -- especially ones that have large staff to run them like the MER-A and -B -- need to have some kind of life-limiting feature. Otherwise, you could never realistically budget them. Also, you have to consider the strain on the shared resources -- the Deep Space Network in particular. There are quite a few systems that depend on the Deep Space Network, which is monopolized to a large extent by Spirit and Opportunity today.
The other major life-limiting feature on Spirit and Opportunity are the batteries. They can't be cycled indefinitely. Opportunity, in particular, with its arm heater always on, is going to overtax its battery system relatively quickly. It will probably get to its 90-day design life, but not much further.
Spirit will likely go quite a bit longer. It's warmer there than expected, which means that they don't have to run the internal heater at night as much as they thought. They are seriously talking about an extended mission for Spirit -- maybe up to 180 days. This would give it time to drive quite a long ways, maybe even up to the nearby mountains about 1.5 km away.
thad
-- I love Mondays. On a Monday, anything is possible.
Re:if it can dust one thing, why not another
by
krlynch
·
· Score: 5, Informative
My understanding from earlier articles is that they aren't "brushing off" the rocks, but rather "grinding" off a circular area of the rock so that they can get to the unmodified interior of the rock. So, even if the arm can reach up to "scratch its own back", so to speak, you probably wouldn't want to use the grinder to dust off the solar panels:-)
Re:What's the underlying technology?
by
aurum42
·
· Score: 4, Informative
They run on Vxworks, a real-time operating system (RTOS) which has been used by NASA for several years now. You have to remember that these aren't run of the mill systems, but ones that need military grade radiation hardened components, and it's amazing what can be done even with a simple embedded system (I wrote a minimal TCP/IP stack and ethernet driver for an 8-bit processor once, the 8052, and while complex). It's mostly technology that has proven to be reliable time and time again, but not all codepaths can be explored even in a simple system. The problem with spirit was apparently in the flash filesystem implementation (sounded like they ran out of inodes, but I haven't seen a detailed analysis).
-- "The slave who knows his master's will and does not get ready...will be be beaten with many blows."Luke 12:47-48
Cool Details on Color Calibration
by
Mean_Nishka
·
· Score: 4, Informative
Not to bring up the color calibration controversey again, but Nasa has published a detailed two-part feature on calibrating the pancam. The first part can be viewed here and the second can be found here.
This feature was presented to the mission managers during one of the 'lunchtime lectures' they present in the MOC. I caught a glimpse of this presentation the other night while watching the NASA TV stream. The presenter mentioned/. during his presentation and talked a little bit about the color debate started here a few weeks ago.
Another geeky thing to enjoy is Maestro, software that allows anyone to download real data from both landers and observe in exhaustive detail what the JPL guys see (they use a much more complex version of the package). It's Java.
-- Vos teneo officium eram periculosus ut vos recipero is.
I don't have a link handy but the reason it wasn't caught in testing is because the longest test they ran was 9 days. The errors started to happen (IIRC) 18 days into the mission.
SP
-- "It is dangerous to be right when the government is wrong." - Voltaire
care and feeding of rovers
by
CleverNickName
·
· Score: 3, Informative
Also why dont the rover have some kind of wipers to stop the buildup?
I wondered the exact same thing, and asked all the scientists I spoke to at JPL (for TechTV) that very question. They said that the added weight, and potential for joints and servos to fail outweighed the possible benefit of wiping off the solar panels. One of them told me that they were effectively routing out milligrams of weight from various areas of the rovers to get the total down.
I didn't ask about the base station (because I didn't think of it -- that would have been a good question) but I imagine they'd say the same thing about weight vs. benefits.
Re:Great -
by
AKAImBatman
·
· Score: 3, Informative
But to supply a generator large enough to obviate the need for solar cells most likely would blow the weight budget (soft landing, remember?). Just my guess.
BZZT. 2.5 pounds of Plutonium per 75 watts of electricity. That's probably not that much heavier than the solar panels. The best part is that you'd need less battery with an RTG (just enough for large power draws) so you can save more weight there than your RTG costs you.
Did a little research on this specific mission (before I was just talking based on my experience with the much smaller satellites I worked on), and I learned some stuff:
The forwarders are much better (bigger antennas, more solar cells = better power budget, higher orbit means the earth is visible for a bigger portion of the day), but they're another link in the system and prone to failure. (I'm guessing that they don't provide as many emergency debug options, either)
This page includes a description of the low-bandwidth control channel that communicates directly to the DSN.
I couldn't find mention of how much use the high gain-to-DSN path gets vs. via-relay-satellites path - does anyone have this info?
Actually, I'm an EE who has has some on-orbit hardware and software. Your examples are kindof primitive because these instruments have been implemented in a variety of very different ways, but I'll run with them.
Cell phones use a range of frequencies. Sometimes these frequencies are reused, and this is either CDMA or TDMA. TDMA is essentially cooperation; CDMA will suffer the same power differential problems that near-frequency transmissions will.
Cordless phones are similar - either multiple FM frequencies (49MHz), or some form of CDMA/TDMA (2.4GHz+). CB's use different AM channels and also use a form of TDMA (you don't start talking until the other guy says "over"... thus, you are time-dividing a single chanel).
Even at different frequencies, transponders* need to have realively close amplitudes- that's what I was saying in a previous post. TV-relay satellites can well-control their uplink power; cell phones are commanded to vary their power by the towers. These options may not be available to mars rovers, where you want even more reliability and have little ability to change the ground stations (i.e. if a tv uplink is wildly putting out too much power causing other uplinks to be lost, you can bet someone will drive there pronto and pull the plug. Or, if the signal is too weak, someone will realign the antenna or replace the power amp)
(*This is probably not a problem for the DSN, where they can much better filter the signals for special situations. Assuming, of course, that a fault hasn't put the signals on top of each other.)
Slashdot Mirror
I guess the idea of a redundant rover is to make sure that errors are not a total loss. But it's nice to have both, especially since Opportunity seems to have found evidence of water. This has been really exciting to follow.
I've found this site very informative, with frequent rover status updates, links to images, NASA press releases and details of rover activities.
"The slave who knows his master's will and does not get ready...will be be beaten with many blows."Luke 12:47-48
the "source" you're looking for is usually the clouds (rain) AFAIK. though i'm no geologist, but i'm pretty sure of that
So, is the power leakage on the Opportunity rover also fixed or are they just going to put up with a shorter lifespan of the machine?
My understanding is that it is still not resolved. Appearently the rovers can still work in the day with a dead (non-rechargable) battery, but the cold from lack of heaters eventually damages electronics. Thus, one way or another it will probably shorten the mission (assuming something else does not bust or dust-up first).
Table-ized A.I.
I have heard that it's really important that space probes -- especially ones that have large staff to run them like the MER-A and -B -- need to have some kind of life-limiting feature. Otherwise, you could never realistically budget them. Also, you have to consider the strain on the shared resources -- the Deep Space Network in particular. There are quite a few systems that depend on the Deep Space Network, which is monopolized to a large extent by Spirit and Opportunity today.
The other major life-limiting feature on Spirit and Opportunity are the batteries. They can't be cycled indefinitely. Opportunity, in particular, with its arm heater always on, is going to overtax its battery system relatively quickly. It will probably get to its 90-day design life, but not much further.
Spirit will likely go quite a bit longer. It's warmer there than expected, which means that they don't have to run the internal heater at night as much as they thought. They are seriously talking about an extended mission for Spirit -- maybe up to 180 days. This would give it time to drive quite a long ways, maybe even up to the nearby mountains about 1.5 km away.
thad
I love Mondays. On a Monday, anything is possible.
My understanding from earlier articles is that they aren't "brushing off" the rocks, but rather "grinding" off a circular area of the rock so that they can get to the unmodified interior of the rock. So, even if the arm can reach up to "scratch its own back", so to speak, you probably wouldn't want to use the grinder to dust off the solar panels :-)
They run on Vxworks, a real-time operating system (RTOS) which has been used by NASA for several years now. You have to remember that these aren't run of the mill systems, but ones that need military grade radiation hardened components, and it's amazing what can be done even with a simple embedded system (I wrote a minimal TCP/IP stack and ethernet driver for an 8-bit processor once, the 8052, and while complex). It's mostly technology that has proven to be reliable time and time again, but not all codepaths can be explored even in a simple system. The problem with spirit was apparently in the flash filesystem implementation (sounded like they ran out of inodes, but I haven't seen a detailed analysis).
"The slave who knows his master's will and does not get ready...will be be beaten with many blows."Luke 12:47-48
This feature was presented to the mission managers during one of the 'lunchtime lectures' they present in the MOC. I caught a glimpse of this presentation the other night while watching the NASA TV stream. The presenter mentioned /. during his presentation and talked a little bit about the color debate started here a few weeks ago.
www.lonseidman.com
Most news sites are too damn slow for news on the rovers. Hell, Spirit was fully up and running over two days ago.
Visit the official MER web site from JPL for at least better day-to-day detail.
Another geeky thing to enjoy is Maestro, software that allows anyone to download real data from both landers and observe in exhaustive detail what the JPL guys see (they use a much more complex version of the package). It's Java.
Vos teneo officium eram periculosus ut vos recipero is.
I don't have a link handy but the reason it wasn't caught in testing is because the longest test they ran was 9 days. The errors started to happen (IIRC) 18 days into the mission.
SP
"It is dangerous to be right when the government is wrong." - Voltaire
Also why dont the rover have some kind of wipers to stop the buildup?
I wondered the exact same thing, and asked all the scientists I spoke to at JPL (for TechTV) that very question. They said that the added weight, and potential for joints and servos to fail outweighed the possible benefit of wiping off the solar panels. One of them told me that they were effectively routing out milligrams of weight from various areas of the rovers to get the total down.
I didn't ask about the base station (because I didn't think of it -- that would have been a good question) but I imagine they'd say the same thing about weight vs. benefits.
But to supply a generator large enough to obviate the need for solar cells most likely would blow the weight budget (soft landing, remember?). Just my guess.
BZZT. 2.5 pounds of Plutonium per 75 watts of electricity. That's probably not that much heavier than the solar panels. The best part is that you'd need less battery with an RTG (just enough for large power draws) so you can save more weight there than your RTG costs you.
Sorry, tree huggers are the problem.
Javascript + Nintendo DSi = DSiCade
Did a little research on this specific mission (before I was just talking based on my experience with the much smaller satellites I worked on), and I learned some stuff:
How rovers communicate with earth
- the Deep Space Network (DSN) communicates directly with the rovers, but is busy because it also tracks 28 other missions.
- the rovers can talk to one of two mars-orbiting satellites that will forward the messages.
The forwarders are much better (bigger antennas, more solar cells = better power budget, higher orbit means the earth is visible for a bigger portion of the day), but they're another link in the system and prone to failure. (I'm guessing that they don't provide as many emergency debug options, either)
This page includes a description of the low-bandwidth control channel that communicates directly to the DSN.
I couldn't find mention of how much use the high gain-to-DSN path gets vs. via-relay-satellites path - does anyone have this info?
HIV Crosses Species Barrier... into Muppets
Actually, I'm an EE who has has some on-orbit hardware and software. Your examples are kindof primitive because these instruments have been implemented in a variety of very different ways, but I'll run with them.
Cell phones use a range of frequencies. Sometimes these frequencies are reused, and this is either CDMA or TDMA. TDMA is essentially cooperation; CDMA will suffer the same power differential problems that near-frequency transmissions will.
Cordless phones are similar - either multiple FM frequencies (49MHz), or some form of CDMA/TDMA (2.4GHz+). CB's use different AM channels and also use a form of TDMA (you don't start talking until the other guy says "over"... thus, you are time-dividing a single chanel).
Even at different frequencies, transponders* need to have realively close amplitudes- that's what I was saying in a previous post. TV-relay satellites can well-control their uplink power; cell phones are commanded to vary their power by the towers. These options may not be available to mars rovers, where you want even more reliability and have little ability to change the ground stations (i.e. if a tv uplink is wildly putting out too much power causing other uplinks to be lost, you can bet someone will drive there pronto and pull the plug. Or, if the signal is too weak, someone will realign the antenna or replace the power amp)
(*This is probably not a problem for the DSN, where they can much better filter the signals for special situations. Assuming, of course, that a fault hasn't put the signals on top of each other.)
HIV Crosses Species Barrier... into Muppets