Mars Rover Remains In 'Critical' Condition...

Spaceflight Now.com ^ | 01/23/2004 | William Harwood

[Ernest_at_the_Beach]

They should have done a single point of failure analysis. Yeah, that's it!

Didn't we have a system in one of the space programs where we had things in three so that all three computers were doing redundant calculations and at certain break points , would check with each other, and the correct answer was decided by majority vote!

Kind of appropriate for a democracy!

[Central Scrutiniser]

Mr. Grudgemeyer got to it:

[Ernest_at_the_Beach]

LOL!

Windows 95 is a guaranteed multiple reboot multiple reboot each and every day!

[Ernest_at_the_Beach]

LOL!

[spokeshave]

Maybe it got a Zap up the Butt from the dangling umbilical cable to platform that was severed.....?

[TMSuchman]

To All Those who responded to my posts;

Yes, I agree that exploration is very dangerous. Just look at our history here on Earth. Thousands of lives were lost in the exploration of our planet. We are driven by something deep down inside us to see what is over the next hill, around the river bend, over the next mountain.
But why send a robot,when it is more than ovious that only a person can do the job right, the first time. yes some may pass away [and it would be a terrible loss to us all], but it is the "cost" of our spreading across our universe. We must send astronauts back up into cosmos now! We have the technology, & the means to do, but due to the nay sayers, we may not have the will.

[foreverfree]

bump

[Ichneumon]

What's worse, a dead Rover or dead people?

Exactly. The cost (in lost money, time, morale, etc.) of a failed manned mission would be hugely greater than the cost of a failed unmanned mission.

Yes, there are problems that people "on the spot" could possibly fix. But there are also more problems that can arise *because* you've got life-support issues to worry about. Overall I'd think that a manned mission would have greater risk of failure than an "unattended" unmanned mission. And the cost of failure is so much higher.

[tm22721]

With our horrendously stagnant technology these days, we are not going anywhere for hundreds of years.

That 'horrendously stagnant technology' has boosted productivity to the point where we have high growth, almost no inflation and companies don't need to hire new workers.

IMHO there is no subsititute for humans in space exploration. If you ever designed a complex piece of software you would understand the impossibility of proving its reliability.

BUMP

[Churchjack]

Gort! Klaatu barada nicto!

[bonesmccoy]

I think the problem in interplanetary exploration is payload mass. You can design redundant systems, but the rover's size and mass limitations preclude a highly redundant system.

It was a stunning accomplishment just to land successfully and return images.

Tonight, we'll see if the first landing can be replicated. The first landing suggests that the EDL team at JPL are the best in the world.

Tonight's landing will put the exclamation point on the sentence.

[al baby]

"

[Professional Engineer]

Yeah, What you said.

[SteveH]

The directory tree looks as if it might be a directory tree for the applications support and applications directories for a VXWorks OS. My (limited) understanding is that VXWorks is a real time OS in which the entire memory space of the CPU; that is, it does not use the virtual address space paradigm of large time-sharing OSs such as Unix and variants (Linux, Solaris, FreeBSD, whatever).

In conventional terrestrial applications, the vast majority of problems are software-related (usually 99+%).

For planetary exploration purposes, the chances of there being a hardware failure is probably boosted significantly.

Redundancy is achieved by various means. Voting was used on the shuttles. Pair-and-spare are used on some proprietary earth applications. A "Cadillac" solution would be to use multiple vendors for separate missions. In effect missions from other nationalities achieve an approximation to this ideal.

A composite of some of these approaches is represented in Arthur C. Clarke's "Rendezvous with Rama," which incidentally appears to be in the process of being made into a movie.

[SteveH]

I interpret that to mean there is no way to hot-swap components manually.

A full redundant system, such as sending two rovers, presupposes all failures are hardware failures due to abnormally harsh environmental conditions impairing the normal operation of the hardware, and that all software problems can be overcome by (a) extensive pre-flight testing and (b) remote field upgrades and reboots.

I am interested in more details about the communications problems. 120 bits/sec is very slow. I wonder if they sidelined their normal (sliding-frame?) more sophisticated communications stack and substituted a simple request-response protocol, which might account for some of performance degradation. They might simply be suggesting in public, or not bothering to contradict the suggestion, that the problem is hardware, because such a description might be too difficult to communicate through non-technical news media outlets.

[Robert_Paulson2]

A composite of some of these approaches is represented in Arthur C. Clarke's "Rendezvous with Rama," which incidentally appears to be in the process of being made into a movie.

---

most kewl.

[SteveH]

The directory tree looks as if it might be a directory tree for the applications support and applications directories for a VXWorks OS.

I now see that the directory tree is for a real time control application put out by Argonne National Labs and called "EPICS", for "Experimental Physics and Industrial Control System." The web site is here.

Collecting information from the web, it appears that the Rovers are using "RAD6000" CPUs. These are are made by BAE Eystems and are based on the IBM RS-6000 RISC-like 32 bit processor architecture. The processors are radiation-hardened. Check this out.

From here the system seems to have a single 20 MHz CPU, 128 MByte DRAM with error recognition and correction and a 3 MByte EEPROM.

VXWorks OS images appear to be traditionally cross-compiled from Unix (Solaris, etc.) systems, so the directory structure of the build tree does not necessarily represent the directory structure of the live filesystem.

The RS-6000 architecture does not appear to be a standard Wind River supported architecture, so VXWorks might have had to be ported to it by BAE Systems in their BSP (Board Support Package)-- another potential source of problems if it was not done carefully...

[JoJo Gunn]

Same tailor?

[boris]

Does the second rover use the same S/W, same version?

If so, its prognosis seems questionable.

Oops.