Spirit Restored; Opportunity Set to Roll Onto Mars

Reuters ^ | 1.30.04 | Reuters

[gcruse]

Good news all around.

[IncPen]

Glenn Reeves said Spirit's apparent return to good health came after engineers deleted about 1,700 non-essential files...

Porn.

[randog]

...it crashed, possibly because the memory was overloaded.

It's nice to see that code jockeys still think that memory is unlimited. It's a universal constant that I've grown accustomed to.

[polemikos]

ALT-CTRL-DEL

[randog]

Yeah, some young engineering intern at JPL is sweating bullets now that his 'secret stash' has been discovered.

[biggerten]

Here's what I don't understand.

From watching the press conferences, I know that the rovers each have 512M bits of flash memory, divided into two 256M bit mirror image partitions.

Now 256M bits / 8 = 32M bytes. If Spirit had 13,000 files, and assuming 100% flash utilization (unlikely, to say the least), that's 2.5K bytes per file, on average.

If I mis-understood the bit/byte thing, then that's still only 20K bytes per file on average.

I have a hard time believing that the file sizes are that small.

There is 128M bits of RAM, and some EEPROM, how much I don't know. I assume there is a boot loader or somesuch in EEPROM, and I know (from the press conferences) that at least some of the actual run-time image is in flash, further reducing the memory available for file storage.

Anybody got a clue? I sure don't.

[IncPen]

I worked at an IT shop at the height of the 'dotcom boom' that took pride in being progressive in many ways

Except when they found that one of the techs had 500GB of porn and was hosting it from their servers. Ouch.

[AppauledAtAppeasementConservat]

"I have a hard time believing that the file sizes are that small."

I can't speak for JPL but back in the DOS days you could do an aweful lot with small files. Adding graphical interfaces and fancy stuff on cumputers takes up alot of space and that most likely would be useless on a robotic rover.

[randog]

Your math looks good, so my explanation would be:

The rover is basically a sensor that's gathering raw data and sending it back to the mothership (earth) where more powerful computers can process it. The files are probably designed to be very compact, e.g. a time stamp, a sensor ID, and sensor data. The pictures would pose a problem, but those might be taken when the satellite passes by and uploaded immediately. I dunno--I'm just speculating here.

[randog]

500 gigs of porn, eh? Back then that would account for a RAID box or two. I'm sure the IT admin was glad to get all that drive space (and bandwidth) back!

[onedoug]

Biogenesis?

[DarthMaulrulesok]

I am no expert on electronics, but I do have a question:

If wrapping a device as complicated as a Mars Lander in air bags and letting it bounce around as it lands is not the best way of getting a probe down without damaging any circuits, why were air bags used? We got the Viking one and two probes down just fine using retro-rockets (I think).

So, could the fact that Spirit spent its arrival time bouncing off hard surfaces account for its later problems? Any ideas?

[Don Joe]

I can't speak for JPL but back in the DOS days you could do an aweful lot with small files. Adding graphical interfaces and fancy stuff on cumputers takes up alot of space

I wrote a DOS shell -- GUI, but character-mode-based -- that fit on two 360kb floppies (or one 720K floppy) for distribution.

It included a DOS menuing system, a GUI configuration program (for creating your DOS app menu entries), a graphical file manager (including a full licenced copy of PKZIP/UNZIP, with a GUI frontend I wrote), and an "in-program" cooperative multitasker (for maintaining the on-screen clock display and animated background).

It also included a Windows 3.x component that I wrote, to allow you to run Windows apps from DOS. My shell would launch Windows, run the selected application, and then sit silently in the background, monitoring your app. When you closed your app, my code would terminate Windows, and put you back in the DOS shell. (It also had options to stay in Windows when your app ended, or, query you as to whether to remain in Windows or return to DOS.) I added that because at that time, many people didn't have a lot of Windows apps, and only went into Windows for the express purpose of running a single program, and they'd go back to DOS when they were done.

Yes, you could do a lot in a little bit of space back then. (Both disk space, and RAM. My shell worked on computers with 640 KB RAM.)

I gave up on my shell when Windows 95 came out and I could see the handwriting on the wall. I'd had a distributor all lined up, too, hot to start publishing it, too. Timing is everything, argh.

[Don Joe]

If wrapping a device as complicated as a Mars Lander in air bags and letting it bounce around as it lands is not the best way of getting a probe down without damaging any circuits, why were air bags used? We got the Viking one and two probes down just fine using retro-rockets (I think).

So, could the fact that Spirit spent its arrival time bouncing off hard surfaces account for its later problems? Any ideas?

I suspect that everything was soldered, and probably potted, too. I remember reading about a satellite that went up a long time ago, it had the motherboard from an Apple II, which had been modified by having all the sockets removed, and every component soldered into place. Then, they potted the entire thing (embedded it in epoxy).

When you know you're never going to have to repair a device, it's not that hard to secure it against an amazing amount of sheer physical brutality.

[Grig]

"about 1,700 non-essential files"

They were all MP3 files and the RIAA is now chartering a mission to Mars to prosecute. :)

[HowlinglyMind-BendingAbsurdity]

Can we send Kerry and Dean into orbit to Mars as a test run of the equipment? Socialism really seems to belong in Outer Space.

[ambrose]

The old Apollo spaceships were run off of 16k computers!

[ambrose]

Someone said on a previous thread that the rovers weighed a lot more than the Viking landers...