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Comment: Re:"Contrary to what we were sometimes taught" (Score 1) 232

by Yoda222 (#48034389) Attached to: Antarctic Ice Loss Big Enough To Cause Measurable Shift In Earth's Gravity

The "gravity constant" that you are describing is the gravity acceleration at the earth surface due to the earth (where you may or may not have subtracted the centripetal acceleration due to the earth rotation) which changes with the position on earth mainly due to the fact that the distance from the surface to the center of the earth is changing (due to flattened at the poles and bulges at the equator). So this is more a change with location than a change with time. The ESA studies is more about the measurement of the earth gravitation from "outside" the earth, to create a model for orbit evolution with time. (Jn parameters, with n>= 2) And they study this evolution in time, for all location. So it's not exactly the same.

(Anyway, the g that you talk about can be seen as an evaluation of the Jx modelisation at earth surface so this is of course related. Bu the study is more about time change than space change)

Comment: Re:A good slice of luck. (Score 1) 35

by Yoda222 (#47915619) Attached to: European Space Agency Picks Site For First Comet Landing In November
The goal is get more information about comets. The only way to reduce the luck in the mission is to get more information about comets. You could probably make two mission, the first one studying a comet, the second one having a landing device. But you will not be sure that the second comet that you visit is similar to the first one. And it will cost a lot more. So adding a secondary landing probe to Rosetta, even if it may fail, is a cheaper solution, yet relying on some luck.

Comment: Re:Not A SW error! (Score 1) 157

by Yoda222 (#47782581) Attached to: Software Error Caused Soyuz/Galileo Failure
That's not what I understand from the article (my understanding of the article don't exclude your interpretation, but I see it differently) You are right, the control software of the Fregat did exactly what it was told to do (assuming the article is correct) but the input was wrong. But was the input directly done by an human or is it the result of another software (more likely) which had an error? If this is the case, then it's a software error. (this could also be an human input error before this software)

Comment: Re:"Programmers" shouldn't write critical software (Score 1) 157

by Yoda222 (#47782559) Attached to: Software Error Caused Soyuz/Galileo Failure
From what I understand (but this article is reporting that some press agency report that someone unamed told them something... the result must be very accurate) it's more likely that a software A gives a bad result to the Fregat control software B. I'm not able to determine from the article is the software A is bad or if there was a bad input to software A which result in this. I understand from the article that software A is also embedded, but see my remark in the parenthesis before about how accurate this article must be.

In order to dial out, it is necessary to broaden one's dimension.