[time-nuts] Space mission comes to an end because of a "computer time tagging" problem

[Hal Murray]

jimlux at earthlink.net said:
> Then on the ground, we time tag  (with an atomic clock) when the telemetry
> frame is received. (giving you "Earth Received Time" or ERT)  Someone on the
> ground does a process of time correlation figuring out what spacecraft time
> corresponds to what TAI time, allowing for the various factors like the
> light time from spacecraft to the earth station.

A friend works at the VLA.
  http://en.wikipedia.org/wiki/Very_Large_Array
They occasionally cooperate with NASA.  He told me roughly the following 
story.

NASA wanted a second opinion on the location of one of their probes out near 
Jupiter or Saturn or ???  No problem.  They collected some data and fed it to 
the computers.  NASA didn't like the answer.  It was way off.  After the 
appropriate amount of head scratching, the VLA geeks figured out that this 
was the first time that they had used that software to look at something that 
was within the solar system.  They fixed it to do the blue-shift corrections 
from "nearby" rather than infinity.  NASA was very happy with the revised 
answer.


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