View Full Version : Y2K8

9th Dec 2007, 14:58
I hear the latest shuttle launch has been postponed until January. After the first postponement they said that they would have to get it aloft soon, because they didn't dare have it in the air when the date changed from 2007 to 2008

wtf? what king of crap computers did they put in this thing?

9th Dec 2007, 15:56
A bit surprised there, thought they had updated this odd shuttle feature. More info on the end of year change over at this website: http://www.nasaspaceflight.com/content/?cid=5026
As to which computers: http://en.wikipedia.org/wiki/Space_Shuttle
Flight systems:
The shuttle uses five identical redundant IBM 32-bit general purpose computers (GPCs), model AP-101, constituting a type of embedded system. Four computers run specialized software called the Primary Avionics Software System (PASS). A fifth backup computer runs separate software called the Backup Flight System (BFS). Collectively they are called the Data Processing System (DPS). The IBM AP-101 computers originally had about 424 kilobytes of magnetic core memory each. The CPU could process about 400,000 instructions per second. They have no hard disk drive, and load software from magnetic tape cartridges.

In 1990, the original computers were replaced with an upgraded model AP-101S, which has about 2.5 times the memory capacity (about 1 megabyte) and three times the processor speed (about 1.2 million instructions per second). The memory was changed from magnetic core to semiconductor with battery backup.

9th Dec 2007, 16:38
:{ :{ :{

I've got better at home

Loose rivets
9th Dec 2007, 16:49
Remember that the computers in 'Station X' could keep up with modern computers...for the job they were made for.

9th Dec 2007, 17:16
And they buy their spare parts on ebay (http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2002/05/12/MN141658.DTL&type=tech).......

9th Dec 2007, 17:17
The CPUs driving the avionics in a B747-400 are about equivalent to a 286... :eek:

9th Dec 2007, 17:27
I've got better at home

Rated to what 'g?'
Tested to what tolerances regarding heating and cooling?
How many interfaces does your home system have to interact with?
To what degree of redundency?
Designed how long ago by what cheapest bidder?

9th Dec 2007, 18:25
You took me seriously? :}

Lamenting Navigator
9th Dec 2007, 20:38
Are they running Windows in the space shuttle? Blimey, would've thought they'd've switched to Macs or Linux by now... Mind you, depends whether they needed to run a webcam or not.

9th Dec 2007, 21:59
You took me seriously?

Yep. Figured you were the quentisential (sp?) eccentric Englishman (living in Texas mind you. Wasn't Billy the Kid's employer an Englishman named Tunstle or the like? But I digress...........) who was building your own one stage to orbit machine to show those Yanks how it's done..........

Or a Mac user.....................

11th Dec 2007, 03:27
wtf? what king of crap computers did they put in this thing?

Mission-critical systems are a different kind of animal than ordinary desktop machines.... at every stage of the evolutionary cycle.

-- Architecture: When the vehicle speedometer has 4 or more digits above the decimal, or it cost several million$ per day for system down-time, one wants to minimise the frequency AND duration of outages when failures occur. This boils down to rather odd partitioning among components and subsystems, redundancy in some places that would otherwise be sparse and sparseness in places that would be redundant in an office desktop design.

-- Software: Right out of the gate the special architecture and requirements for robust failure recovery, "hot" repair, fail-soft behavior and interfaces to other spacecraft systems requires highly unique software.. by definition very different even if patterned after some existing design. Because of this it becomes a 1-up design, thereby. reducing ease and practicality of substitution of new at later stages of the project.

-- Reliable Components: special attention to details - even minor ones - to increase reliability and reduce chance of failures. The hundred-dollar flat washer sometimes makes sense in this context. Could become a million-dollar flat washer if that demonstrably makes a difference in the probability of survival and ultimate success of the mission.

-- Space capable: ditto to "Reliable". Vibration, G-forces, Radiation, cooling oddities, attention to having non-toxic combustion byproducts, testability, shelf-life, etcetera. Maybe there are a hundred specific reasons why one spends a pile on space-qualified hardware when allowed to do so.

-- Mission Plan, Mission Creep and Mission Ratchet - all project-related phenomena that lead to convergence on a single solution package that is valued, regardless of the age of the technology, because it all finally works, it uniquely fits the program dynamics, it is precisely testable and accountable, etc. General philosophy is :" if it doesn't work, find a fix. And if it does, do not mess with anything in the design."

These are roughly the same reasons why you may have some difficulty obtaining permission to put a blue-ray disk player in the panel of your
personal 747.

11th Dec 2007, 12:45
Slightly off topic, but in line with the original question...
The delay for the launch has something to do with a malfunctioning fuel gauge. Now this is pretty funny since regardless of what said gauge shows there are no filling stations up there. It's not like they'll turn to each other and say "Capt'n, you think we should pull into the next Shell, top 'er off and I gotta take a wiz?"
So delaying because of a gauge seems rather pointless.

11th Dec 2007, 12:48

11th Dec 2007, 13:08
I might be replying to a wind-up but still

The ECO sensor (Fuel Gauge) that have troubled so many launches play a rather vital role in the whole launch of the shuttle. The effects of no propellant or oxidizer reaching the turbopump has rather disastrous effects on the engines (something along the lines of very rapid disassembly). The role of the ECO sensor is to cut off the main engines as soon as they go dry, thus prevent the destruction of the SSME.