The Forgotten Huygens Experiment

jdray writes "An experiment onboard the Huygens probe didn't run as planned because someone forgot to turn it on. The team lead for the experiment has put eighteen years of his life into the project, just to watch it not happen after a seven year ride to its destination on Titan."

Comments

Slashdot post is wrong

[Anonymous Writer]

This is what the slashdot post says...

An experiment onboard the Huygens probe didn't run as planned because someone forgot to turn it on.

But I got this out of your linked article...

Huygens was programmed to transmit telemetry and scientific data to NASA's Cassini Saturn orbiter for relay to Earth using two redundant S-band radio systems. Channel A was the sole path for an experiment to measure wind speeds by studying tiny frequency changes caused by Huygens' motion. In one other deliberate departure from full redundancy, pictures from Tomasko's descent imager were split up, with each channel carrying 350 pictures.

As it turned out, Cassini never listened to channel A because of a software commanding error. The receiver on the orbiter was never commanded to turn on, according to officials with the European Space Agency.
...
Even the lost wind measurement data will be made up, thanks to a remarkable effort on the ground to monitor a faint carrier signal broadcast by Huygens - the equivalent of a cell phone call at a distance of 751 million miles - using a network of 18 radio telescopes around the world. That data, which not as precise as the Doppler information that was lost, should fill in the blanks.

And I also found this article online. Here's an excerpt...

Atkinson had a Doppler wind experiment onboard the probe which landed on Saturn's moon Titan after dropping from the Cassini spacecraft. Atkinson and other team members estimate they had put in nearly eighty- man years to bring that experiment to a conclusion this past weekend.

However, a command to turn on the instrument being used by Atkinson's team was not in the command sequence. The entire experiment was lost. There is some hope that some transmitted data was picked up by radio telescopes back here on earth, and if so, then an Earth- based version of the Doppler experiment may still be possible. ...
The Cassini mission, he says, has been incredibly successful, and he says eventually they'll get the wind measurements they needed, but definitely not how they planned, and he says it will take a long, long time.

The reports are confusing and I can't tell what happened. Was there a measurement device onboard the Huygens probe gathering data and transmitting it (like the Slashdot story suggests), or was the data supposed to come from the measurement of the signal from the Huygens probe in relation to the Cassini orbiter?

If it was the former, is the data not as good because the Earth radio telescopes didn't pick up the entire signal, because there was signal degradation, or because they have to piece all the data together from all the different radio telescopes? If it was the latter, is the data not as precise because of the proximity from the transmitter to the receiver?

Either way, the Slashdot post is wrong. If it was a measurement device solely on the Huygens probe, it was turned on- it was the relay onboard the Cassini orbiter that wasn't turned on. If the data was meant to be gathered from the proximity of the transmitter to the receiver, then the experiment wasn't onboard the Huygens probe but was actually meant to be a collaboration between the probe and the orbiter.