[X] My Assistant

[djellison]

I'd like to see peoples thoughts regarding ESA's website, it's press 'accesability', it's image release protocol etc.

What does ESA do that's good?

What does ESA do that's bad?

What does NASA do that ESA SHOULD do?

What does NASA do that ESA SHOULDNT do?

What benefits might there be etc etc

I'm trying to gauge the 'educated' public opinion on the matter. Please say, if you reply, which country you're from.

Im going to add a poll as well.

Also - please comment on specific features of NASA public relations and press activity that you find superb, and htose that you find terrible.

Doug

[The Messenger]

We still do not have a full explanation for why Huygens 'A' channel failed, and we still have not even seen a plot of the radar or sonic data.

OK, buried in the Nature papers there is a brief discussion about the sonar, and a 'representation' of the radar data, but no detail and NO TIME STAMPS!

Come on, peer reviewers! These charts should contain critical mission timing information!

How can the probe have been swinging like wrecking ball just prior to landing (as seen in the DISR images), but at the same time, not recorded any acceleration on any of the accelerometers! And the landing accelerations: less than 100 milliseconds - I thought this might be due to aliasing, but the sampling rate was 200 Hz. A 200kg framework impacting at > 5m/s with no bouncing, no structural tension and backlash? What were the accelerometers mounted on? A brick thrown into quicksand?

I have stated before (based upon the Doppler signal), that I think the probe hit the surface ~20 minutes after entry. This is consistent with the ABC accelerometers, as well at the frequency domain plot of the radial accelerometer.

But what about the sonar, the tilt meters and the radar? I can't tell, because they have not presented the data with a proper timing axis.

The radar altitudes - both channels - were time-stamped into the housekeeping data at one second intervals, so there should be no question of when this radar data was collected - where is the time-stamped housekeeping data?

[djellison]

I have stated before (based upon the Doppler signal), that I think the probe hit the surface ~20 minutes after entry.

You can actually see the landing event on the doppler, and it's certainly not 20 mintues after entry, that's just silly.

Doug

[The Messenger]

You can actually see the landing event on the doppler, and it's certainly not 20 mintues after entry, that's just silly.

Doug

If you sum the curves from all the free planes of motion, (vertical, longitudinal, and latitude), and subtract all the fixed rotations, the residual 'A channel' Doppler motion from ~ twenty-five minutes into the decent is a flat line, albeit a noisy one. There is a chart demonstrating this in one of the early Bird presentations.

The penetrometer probe was scheduled to be armed when the radar detected the altitude was 8 km, but if the probe hit the surface after only twenty minutes, even if both radars were working properly, the software would have assumed the radar lock was ambiguous. (Twice the nodal frequency for the probes radar ~40 km).

After this, if the probe was sitting on the surface, the radars would never achieve 'lock' again, and the penetrometer never armed - until the time-out period for the decent phase of the probe expired, fifteen minutes after the expected landing time.

I think the short, minimal accelerations registered at the time of the 'landing' are consistent with a penetrometer thrust, but not a 5 m/s impact. (This is also consistent with the non-transmittal of the spectrometer sequence, which was also 'radar-altitude scheduled' just before the landing.)

This can easily be resolved with either time-stamped radar, or time-stamped sonar plots. The ESA has put together the most plausible decent they can with the evidence in hand. If in order to do this, they had to discard, as suspect, some of the housekeeping data, that may be a reasonable assumption. But they should not publish the plots without a time axis, or a justification for not including this information with the plots.

[djellison]

If you sum the curves from all the free planes of motion, (vertical, longitudinal, and latitude), and subtract all the fixed rotations, the residual 'A channel' Doppler motion from ~ twenty-five minutes into the decent is a flat line, albeit a noisy one. There is a chart demonstrating this in one of the early Bird presentations. 

By all means post that chart and give us some evidence for you astonishingly outlandish claim. I still think your supposition is very very silly. There is an accurate, detailed, step by step timeline that outlines every event on the spacecraft from wake up to landing as taken from spacecraft data. I'd love to see why you think you know better than the people who designed, built and flew the probe. The most obvious piece of data is that the Penatrator gives an accurate time of impact, and it sure as hell isnt 20 minutes after entry.

Doug

[The Messenger]

By all means post that chart and give us some evidence for you astonishingly outlandish claim. 

I cannot post the graphs, they are not officially in the public domain, but you can see them in this presentation, page 8. (caution, high speed only)

http://www.mrc.uidaho.edu/~atkinson/Huygen...resentation.pdf

Notice how - the horizonal and vertical velocities are virtual mirror images of each other from 34 minutes after t-0 until the end of the plot. This is either a rather odd coincidence, or the probe wasn't moving. Just as strange is Huygens "negative' vertical velocity between 15 and 25 minutes after T-0, which indicate the probe was rising at up to 25 m/s! The kinetics needed for such a rapid rise aren't there, and we would not see the stratified layers when viewing Titan's limb if they were.

These plots do not include the landing time, I assume because they do not include the "Parks" data - but the zonal wind retrieval on the next page includes the Parks data. I must caution, this is preliminary data, but I think it is consistent with what has been reported in Nature.

I still think your supposition is very very silly. There is an accurate, detailed, step by step timeline that outlines every event on the spacecraft from wake up to landing as taken from spacecraft data.

We know the reconstruction of this data was quite difficult, in part because of the loss of Channel A. There is also at least one unconstrained parameter: Without the Doppler wind data, lateral motion had to be inferred. We are still waiting for VLA data, which could better constrain both lateral motion and the landing site.

The accelerometer readings don't pass basic sanity checks, especially when they are compared with the wobbles in the DISR images, just before landing. Something isn't right - either the probe landed much sooner, or the accelerometers quit taking an accurate pulse.

I'd love to see why you think you know better than the people who designed, built and flew the probe.

If the radar and/or sonar data in the time-stamped housekeeping data jive with the penetrometer landing time, the answer to that question is moot. Suffice for now to say I have considerable experience with this family of data.

The most obvious piece of data is that the Penatrator gives an accurate time of impact, and it sure as hell isnt 20 minutes after entry.

The penetrometer was only a good indication if it was armed-and-polled by the CPU. The penetrometer circuitry was not scheduled to be polled until the altimeter indicated the probe was less than 8 km from the surface. The time-stamped altimeter data is necessary to validate when the penetrometer was polled.

There is also the not exactly trivial fact that the atmosphere density and temperature profiles in the lower stratosphere and troposphere are nearly a perfect match for the Voyager 1 radio occultation measurements on ingress and exit. This would not be possible if the atmosphere profile and Titanian radius were more than trivially different from the predicted values.

The Huygens temperature and pressure profiles are not time-stamped either! The fact that the first, the highest Huygens' altitude pressure readings are greater-than-expected is consistent with my argument that the probe first sensed the atmosphere at a lower-that-expected altitude - remember, above 40 km, the altitude is inferred from the Doppler data, and is not laterally constrained.

[djellison]

I cannot post the graphs, they are not officially in the public domain, but you can see them in this presentation, page 8. (caution, high speed only)

http://www.mrc.uidaho.edu/~atkinson/Huygen...resentation.pdf

Notice how - the horizonal and vertical velocities are virtual mirror images of each other from 34 minutes after t-0 until the end of the plot. This is either a rather odd coincidence, or the probe wasn't moving.

If it wasnt moving, both would be zero would they not

And correlation between altitude and wind speed is to be expected - it's exactly what we have on earth.

How do you explain the graph on page 9 if the spacecraft was stood still? The sudden spike around the time you think it landed is simply a high altitude wind sheer. Again, something we see on earth.

Honestly, saying something like that is somthing I'd expect of Hoagland.

Doug