Simulations May Explain Loss of Beagle 2 Mars Probe 98
chrb writes "Researchers at Queensland University have used computer simulations to calculate that the loss of the US$80 million British Beagle 2 Mars probe was due to a bad choice of spin rate during atmospheric entry, resulting in the craft burning up within seconds. The chosen spin rate was calculated by using a bridging function to estimate the transitional forces between the upper and lower atmosphere, while the new research relies on simulation models. Beagle 2 team leader Professor Colin Pillinger has responded saying that the figures are far from conclusive, while another chief Beagle engineer has said 'We still think we got it right.'"
Re:How weird (Score:5, Insightful)
another chief Beagle engineer has said 'We still think we got it right.'
They got it right, yet the mission failed. What sort of weird mental block do these people have?
Something else might have gone wrong even tho the choice of spin rate was the correct one.
Re:How weird (Score:5, Insightful)
Re:How weird (Score:5, Insightful)
Crazy talk (Score:3, Insightful)
Explanation? (Score:4, Insightful)
There is undoubtedly something to the contention that a computer simulation does some explanatory work, but it must be in a roundabout way. Maybe this: the computer simulation provides evidence to the effect that some prior event was able to cause the known outcome; but then it is the prior event (the bad choice of spin rate in this case) that explains the loss of the Beagle 2, not the computer simulation.
Re:Come on, it's british (Score:1, Insightful)
Name a one thing british ever made right.
Beer.
Re:How weird (Score:1, Insightful)
Those things are a bit expensive, so rather than have 3 of those probes burn up one after the other due to a design fault or cosmic rays; they send one, check the results, and only *then* think about sending another.
Re:How weird (Score:4, Insightful)
If the spin rates were off afterall, then they could have lost two or three probes instead of one. It's always a gamble, and if a mistake with big consequences has been made, sending more probes might not give you more chance of success...
Re:Come on, it's british (Score:3, Insightful)
Calculate This (Score:5, Insightful)
How many different independent forces could have influenced Beagle? Represent each with a variable. Calculate how many emergent properties could have influenced the craft (those arising from interactions between main variables). Assign these a variable. Estimate the range of values for each variable. Calculate the dynamics of each variable (ie. linear, logarithmic, hyperbolic, etc., including estimation of those whose behavior does not fit a simple function, instead requiring complex functions). For each variable, estimate a reasonable granularity (they may be analog, but the resulting computation would include infinities, so digitizing is necessary). Calculate the matrix necessary to represent all the possible results. Determine whether the calculations could be completed in polynomial time. Almost certainly not, so estimate how many variables (and their dynamics) must be retained and drop the rest. Calculate the solutions matrix for this reduced set. Check for polynomial time solution. If no, reduce yet again. With each reduction estimate the error range introduced, and whether any of them are unacceptable and the prior value retained.
Estimate the amount of computational power/time necessary to complete the solutions matrix, including the cost of buying/building/renting/etc. and your available resources. Calculate how many orders of magnitude there are between what's necessary to solve the problem and what you have to work with. From that estimate how much you have to reduce the solutions matrix in order to be able to arrive at some solutions, as well as how inaccurate any results will be.
Once you have the calculation of the solution set down to polynomial time and within your budget, look at how inaccurate your results will be. If the accuracy is found to be acceptable, and the calculation therefore worth doing, chances are you've made a mistake in your estimations. Almost certainly the inaccuracy will become too great before your reductions result in a solvable problem. Also note that the minimal matrix dimension will probably not be an integer. Choosing the best number of variables would be trivial, as you simply choose the next highest integer. However just because the solution here is between N and N+1 does not mean that there is only one variable with a fractional influence; estimate how many and which variables are best characterized as non-integers and select the best set of variables to use in the model. Calculate how far back into non-polynomial time your solution estimate has drifted, or at best how far over your resource budget the calculations will require.
Take a dose of analgesic of your choice sufficient to eliminate your headache. Begin building a model using the minimum number of (integer) variables necessary to arrive at a variable/value set that produces a result matching the behavior of the phenomenon you wish to model. Ignore the probability calculations that would indicate how likely it is you're wrong, and how many such wrong solutions you'll arrive at before you happen on a possibly right solution. Instead of using probability estimates to calculate statistical significance of any calculated solution, use the fact that a solution can be found that results in the same behavior as the one to be modeled, and wrongly call that accidental similarity 'practical significance'. Publish a factually unsupportable assertion that your model describes what happened based only on the fact that your model achieves the same result and count on the fact that nobody else on your research team, or anyone for that matter, is capable of accomplishing the necessary calculations described here to conclusively state you're wrong, or at best that you can't say you're right.
Estimate the positive influence the number of publications, regardless of validity, has on the probability of receiving future funding and amount thereof. Conclude that minimal-guess "modeling" provides you with the ability to say something that sounds reasonable whereas attempting to achieve real validity would take too
I hate to break it to you, but... (Score:4, Insightful)
but that's not how it works in grown-up land.
...slashdot's not grown-up land.