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NASA proves once again that, for it, the impossible is not even difficult.

Jog your memory of some few but noteworthy software design errors by NASA/contractors:

1997: Mars Pathfinder. Data Losses, repeated. Error in RTOS, task scheduling priority inversion yielding deadlock. System hardware/software transient yielding a case not practical to analyze, predict or simulate.

1999: Mars Climate Orbiter: Orbit insertion failed. Error in conversion from imperial to metric units.

1999: Mars Polar Lander: System of Systems logic error causing premature engine shutdown in descent.

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IMO: System/software errors are proportional to the number of software engineers working the same project. Fewer is always better.

To Err Is Human. To Truly Screw-up Takes A Computer.

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stevech
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MitchAlsup sent on February 14th, 2011: |

Reply to
Paul Colin Gloster

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Actually, 30 degrees is 1/sqrt(3), which is even steeper than 6/12. A

6/12 roof pitch might be scary for the average person, but not for anyone who has spent any amount of time working on roofs.

Today was warm enough that I could venture from my home for any reason other than to get into my car or to shovel snow. The steepest driveway within steps of my home is about 3 in 10 (or 4 in 12). Lots of sand on that driveway now. There is a road I have to walk further in icy conditions to get to that I estimate to be even steeper and which also has some pretty steep drives on it. Going down that road in snow and ice, you want to keep your foot off the brake (I have a manual transmission). I have never ventured to approach that roadway from the steepest direction in snowy conditions going uphill. When the weather is warmer still, I will venture forth with my carpenter's level. ;-)

Robert.

Reply to
Robert Myers

Paul Colin Gloster sent on February 14th, 2011: |-------------------------------------------------------------------------| |"On 2011-02-12, Del Cecchi wrote: | ||-----------------------------------------------| | ||"Actually you can kill someone with a bicycle."| | ||-----------------------------------------------| | | | |Maybe we should restrict normal modes of transportation | |to walking and pogo sticks. | | | ||-----------------------------------------------------------------------|| ||" Hell, I damn near killed || ||myself. Anything that causes your head to strike a hard surface at any|| ||significant velocity, like falling down from a standing position, will || ||do it. Wearing a helmet is a small amount of protection. I got a nasty|| ||concussion and was wearing a quality bike helmet when I hit a patch of || ||sand." || ||-----------------------------------------------------------------------|| | | |Wow. Thanks for the heads up (ho ho). | | | |I use a Limar helmet. What brand of helmet were you using, so that I | |can avoid it when I shall need a new one? | | | |[..]" | |-------------------------------------------------------------------------|

Hi!,

I never received a response to this. My Limar helmet is old and I could do with replacing it some year. A car crashed into the bicycle which I was cycling today, but I survived and I would like advice of inferior helmets to avoid buying.

Yours sincerely, Colin Paul Gloster

Reply to
Colin Paul Gloster

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