New Horizon Instrument Capabilities Options

[Tom Tamlyn]

During the press conference recorded on January 15 (rebroadcasted on NASA TV this morning), several of the New Horizons instruments have been described as the most capable ever carried for a planetary reconnaissance. For "reconnaissance" I guess we should understand "fly-by," i.e., the instruments are more powerful than those carried by the Pioneers & Voyagers.

It would be interesting to learn how they compare with the corresponding instruments on Cassini & Galileo, with their much higher payloads.

TTT

Edit: I just heard Craig Covault from Aviation Week catch this issue, but he didn't pursue the comparison beyond Voyager & Pioneer.

This post has been edited by Tom Tamlyn: Jan 18 2006, 06:08 PM

[ljk4-1]

A What If group of questions:

Suppose that in 1980, NASA/JPL, realizing that they could not penetrate the clouds of Titan or even hope to see any surface through gaps in the clouds (and even if they could have, no doubt it would have left everyone seriously confused), had redirected Voyager 1 to flyby Pluto around 1990.

In addition to the fact that we would have long known about a few more moons of Pluto besides Charon, what do you think would have been changed/modified/ replaced on New Horizons had the Voyager 1 flyby taken place? Would Voyager 1 been up to the task at all? I remember its images were not quite as sharp as Voyager 2's.

Would NH even exist if Voyager 1 had explored Pluto?

Do you think Pluto will be all that different from Triton - besides the fact that it won't have a big blue world in the background?

[JRehling]

A What If group of questions:

Suppose that in 1980, NASA/JPL, realizing that they could not penetrate the clouds of Titan or even hope to see any surface through gaps in the clouds (and even if they could have, no doubt it would have left everyone seriously confused), had redirected Voyager 1 to flyby Pluto around 1990.

In addition to the fact that we would have long known about a few more moons of Pluto besides Charon, what do you think would have been changed/modified/ replaced on New Horizons had the Voyager 1 flyby taken place?  Would Voyager 1 been up to the task at all?  I remember its images were not quite as sharp as Voyager 2's.

Would NH even exist if Voyager 1 had explored Pluto?

Do you think Pluto will be all that different from Triton - besides the fact that it won't have a big blue world in the background?

First of all, it's hard to say what we wouldn't have known about Titan. Perhaps Cassini/Huygens would have been designed in a well less adapted to the quirks of Titan. Some Voyager discoveries were duplicated from the ground, but who knows if people would have been clever enough to conduct the right investigations without the Voyager 1 benchmark.

It's very unlikely that Pluto would have earned a followup if Voyager 1 had flown by -- but that depends upon what Voyager would have found! If Pluto has rainbow-colored lakes and the message "HELLO" on one face and a duplicate of the Rolling Stones logo on the other, then yes, we would have flown a followup. If it looks like Oberon, we probably wouldn't have.

I don't expect anything so theatrical. The biggest differences vs. Triton should stem from:

1) Triton had and has huge tidal interactions from Neptune. Pluto probably faced something much milder in braking into synchrony with Charon. Pluto may show as little thermal evolution as Callisto (which tidally-braked into synchrony with Jupiter, but shows no surface scars from that).

2) Triton is always the same distance from the Sun, while Pluto has a wildly elliptical orbit introducing long seasons. Triton does have axial-tilt seasons, but the global solar heating budget is about constant.

3) Pluto probably was thumped royally in a collision that produced Charon, although that may have been so early in its formation as to show little present evidence. Triton may be different from Pluto in not having been thumped similarly.

4) Something else. Even when worlds seem to be similar in bulk composition and solar distance, they often end up quite different. The saturnian satellites show that fact off over and over. We'll have to wait and see.

Priors aside, we know that Pluto has some very dark areas on its surface while Triton does not. Something explains that. Maybe it's because seasons on Pluto lead to a significant freeze/thaw of the atmosphere, and the dark patches are now (still) thawed.