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ExoMars
elakdawalla
post Jun 24 2006, 10:41 PM
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QUOTE (Greg Hullender @ Jun 24 2006, 09:52 AM) *
Has anyone proposed a manned mission for the purpose of controlling one or more rovers from orbit...
Yep, that's a pretty clear way to make the most of human brains & robot brawn. Let the humans stay in orbit with a nice big station that you don't need to land, and let them run remotely operated robots all over the place that can stay out there all the time, don't need to come in at night (or in winter), don't need the constant "maintenance" that us humans need. This is considered to be the only feasible way to do "human" exploration of Venus. It was also one of the motivations behind our original "Red Rover, Red Rover" project with LEGO. And we still have the pipe dream of a project in which we'd build some kind of nanorovers that could be landed on the Moon -- and then operated by members of the public, for no other reason than how cool it would be for you to be able to sit down at your computer and drive a rover that was actually on the Moon. Wouldn't that be neat? Someday...

--Emily


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djellison
post Jun 24 2006, 10:54 PM
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I confess...I've driven every functional RRGTM station I could find - and even made a little mosaic from one of them (long lost...but I might try and make another one biggrin.gif )

Doug

(PS - attached one from the Davis Creek Elementary site....the TPS one worked for a bit, then the top half of the interface wouldn't refresh sad.gif If I can get it working again, I'll do a pan from there as well....but I have to say, the calibration process is shocking laugh.gif )
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elakdawalla
post Jun 24 2006, 11:43 PM
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Beautiful work, Doug! biggrin.gif

To get the TPS one to work better I have to give a kick in the pants to the guy who is SUPPOSED to restart its computer daily...who usually remembers to do so for a couple of days and then, well, it doesn't happen anymore...sigh...

--Emily


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RNeuhaus
post Jun 25 2006, 01:29 AM
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QUOTE (djellison @ Jun 24 2006, 03:58 PM) *
Actually the CPU's in most modern spacecraft are more like 1/10th the performance of a Pentium 3....and what's more, there's not much requirement for anything better.

Now - you could argue that it's cyclical - the need for more on orbit computing power has not arisen because people have programmed for what is available and that's tended to be 'enough'. Also - spacecraft are tending to become little centres for distributed computer, with each instrument having it's own processor dedicated to the aquisition, compression and storage of it's own data - it leaves the CPU of most spacecraft doing the comparatively simple task of attitude control, data management, and streaming stuff through to telecoms etc.

I'm sure if there were something 10x faster availabel for on orbit computing, it would be utilised...but the fact that such a processing system isn't in place perhaps suggests it isn't really that necessary.

You drop the bloated OS, the graphics and so forth, dedicate the use of your CPU to on orbit computing, and actually, the mathematics behind a spacecraft are comparatively simple.

Doug

Yes, sure that NASA has selected rightly the capability of microprocessors for the missions of MRO and MSL since they aren't going to need a more powerfull microprocessors to support the mission cores that is mostly dependent by remote control principally to MSL. If NASA has put more effort about the improvement navigation autonomy of robot, sure MSL will need a more powerfull microprocessor to depend less from Earth remote control. Hence, the geology and biology scientific missions would be more productive with improvement advancement and faster return of results.

Rodolfo
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elakdawalla
post Jun 25 2006, 01:39 AM
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Question -- would faster microprocessors also require more power?

--Emily


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RNeuhaus
post Jun 25 2006, 01:54 AM
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QUOTE (elakdawalla @ Jun 24 2006, 08:39 PM) *
Question -- would faster microprocessors also require more power?

--Emily

Definitely, yes. That is one of the engineering concerns.

However, there is a new variety of microprocessors which are energy efficient, inclusive much energy economy than RAD750 and are much more powerfull such as the Intel Centrino of last genertion which as capable as the last model of Pentium IV.

Rodolfo
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mchan
post Jun 25 2006, 05:19 AM
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Well, I wouldn't say definitely. In general, power = C*v^2*f where C is a constant depending on the number of gates and the process (how small the gates are), v is the supply voltage, and f is the switching frequency. You can bump up the frequency and keep the same power by improving process and reducing supply voltage.

Terrestrial bound commercial microprocessors have kept pushing process improvements (lower switching and quiescent power per gate), and supply voltage reductions. Analagous improvements in rad-hard microprocessors are more difficult and have been slower-paced since reducing gate geometries and switching threshold voltages typically makes them more susceptible to particle induced single event upsets. And there is less economic demand for rapid improvements in rad-hard proceessors than in commercial processors. Rad-hard processors are thus more likely than commercial processors to require more power for higher switching frequencies.
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helvick
post Jun 25 2006, 10:09 AM
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QUOTE (mchan @ Jun 25 2006, 06:19 AM) *
Rad-hard processors are thus more likely than commercial processors to require more power for higher switching frequencies.

100% true however it is worth pointing out that as the technologies improve the general trend is towards (much) more computing power per watt within similar processors.

The MER RAD6000 from BAE consumes 20watts @ 20Mhz. The RAD750 comsumes 5-14watts @ 132Mhz. The 750 in it's most stringent radiation hardened mode is at least 20x more efficient (in terms of instructions/watt) than the 6000 used on the MER's.
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RNeuhaus
post Jun 26 2006, 12:12 AM
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QUOTE (mchan @ Jun 25 2006, 12:19 AM) *
Well, I wouldn't say definitely. In general, power = C*v^2*f where C is a constant depending on the number of gates and the process (how small the gates are), v is the supply voltage, and f is the switching frequency. You can bump up the frequency and keep the same power by improving process and reducing supply voltage.

Thanks for your comments which are good.

About the power consumption of microprocessors depends what you mentioned (more gates or transitors and frequency, leads greater temperature due to greater power consumption in Watts). There is a limit of temperature that the semiconductor material becomes unstable its electrical conducting properties (leakages currents). That is the Moore's law.

The other factor that influences the consumption of watts is related to the type of material (Bipolar versus CMOS). Historically, there is a growing power consumption when the frecquency and number of circuits grows until a change of material technology, drops the power consumption. As an example: Bi-polar material was requering lots of much power energy versus CMOS. Now there is a new variety of CMOS which needs less power than the original CMOS for the same frequency and density of circuit.

So I was saying the previous post as the general principle. However, a new semiconductor material technology helps to consume less power for the same computing capacity.

Rodolfo
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mchan
post Jun 26 2006, 09:13 AM
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Sounds like a different Moore than the one I am familiar with. Something may be getting lost in translation here. What you refer to as material, e.g. bipolar vs. cmos, I would refer to as design. Or in your other use of material, I would use process technology. Detailed discussion of semiconductor physics and fabrication are getting somewhat OT here. Suffice to say that there will be continued improvements in computational power per watt in processors, whether commercial or rad-hard. Care should just be taken in comparing performance / power of commercial vs. rad-hard. Somewhat different beasties.
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djellison
post Jun 26 2006, 09:36 AM
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Actually - the current interpretation of Moore's law is that processor density will double every 18 months. People read that as a double of CPU performance every 18 months, but that's not true.

Doug
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RNeuhaus
post Jun 26 2006, 05:15 PM
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I agree to leave the above discussion about the microprocessors power consumption since it is too complex and vast which would lead a very long discussion to understand the technology trends versus power consumption. Besides this theme is not focused to the above topic: ExoMars. I forgive to the audience due to the confusion and noise. sad.gif

Rodolfo
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Stephen
post Jun 27 2006, 08:00 AM
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QUOTE (djellison @ Jun 23 2006, 12:39 PM) *
"[I]n that respect nothing much has really changed since the days of the Soviet lunar rovers of the 1970s and it seems unlikely to change any time soon; and even if it could change it needs to be remembered that a rover is really only a kind of proxy explorer for its human controllers on Earth."

Actually - that's not quite fair - Sojourner and MER were both able to be given a target point, and make progress toward that target point, and would avoid obsticles in the way, navigate around them and return to the target point. There was one great example where Spirit actually gave up and drove backwards around an obsticle early on.

So yes - you couldn't say to Spirit "go to the top of Husband Hill " from the rim of Bonneville..it still requires people in the loop on a daily basis - BUT - it's a lot smarter than you give credit for really.

Doug

I fully appreciate that the remarkable achievements of both Spirit and Opportunity have only really been possible due to the software "smarts" in them. But at the same time we need to keep things in perspective. The reality is that most of the rovers' intelligence is still sitting inside human brains on Earth. In fact had it not been for the greater distance to Mars and the intermittent nature of communications with the rovers those rovers would probably be being driven in real time--or almost real time, as in the case of the Soviet Lunokhods. Or at least the people with control of the funding would doubtless have queried the need to spend money on autonomous driving for them--just as car manufacturers have never (well, at least until recently) bothered spending money developing cars which drive themselves or which prevent their human drivers driving into power poles or off cliffs. They rely on the human beings at the wheel being smart enough not to do such things.

Since the rovers' human masters can't drive their proxies in real time, however, that has necessarily meant giving the rovers a large degree of autonomy. Without that they would not have been able to accomplish their mission at all.

But we should not kid ourselves. The "smarts" the rovers do have are largely there to stop the smart humans doing dumb things with their martian proxies by telling them to do things which may damage the rover or the mission. Like telling the rovers (unwittingly) to drive off cliffs or over tall boulders. In particular AFAIK the rovers have no learning capability. The "smarts" they do have are largely wired into them. If they do make a blunder--like wandering into a sandtrap--it's up to their human masters not them to learn the lesson and then find ways to avoid it happening again, such as tweaking software parameters or not sending them through places where the same conditions that caused the blunder might occur again.

So like I said. Let's keep things in perspective. Spirit and Opportunity are undoubtedly "smarter" than their predecessors. (Remember that famous pic of Sojourner with one wheel perched against a rock many times larger than itself, as if it had been attempting to scale it before it realised its blunder? smile.gif ) But at the same time those "smarts" are also largely an illusion, the product of clever programming, just as an old computer program named "Eliza" could give users the illusion of talking to a certain kind of psychiatrist.

One day rovers & other bots will be able to do a lot more for themselves. They'll need to if their human masters are ever to send them into places where communications with their masters become not merely intermittent but impossible, such as driving down martian lava tubes or diving beneath the ice of Europa. But that day is not here yet.

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Stephen
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Cugel
post Jul 12 2006, 08:02 PM
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marsdaily

Here they talk about Exomars having more autonomy. It sort of has a backseat driver build in....
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SkyeLab
post Jul 17 2006, 02:01 PM
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ExoMars prototype on show at Farnborough Air Show.
Link to a webcam situated on the test bed chassis "Bridget"
http://www.eads.net/web/lang/en/1024/conte...6/41401960.html

Story at http://news.bbc.co.uk/1/hi/sci/tech/5186596.stm

Cheers

Brian


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