It cannot. The light from that event, which is called recombination, is at z = 1100. I.e., it's been redshifted 1100-fold,
from near infrared at the time of recombination to microwave now. That's what the cosmic microwave background is.

My understanding was that the NH team hadn't yet identified any clearly accessible KBOs. The 16 Aug issue of Science, however, notes that "the team has already found 31 candidates perhaps close enough to the current trajectory that small thruster tweaks would bring New Horizons in for a close encounter with one or two of them." I recognize that "perhaps close enough" isn't entirely inconsistent with "none yet found," but the new language had me wondering if anything more definitive has yet been released.

If memory serves, a great many features on the Moon were believed to be volcanic vents, but few of these assignments survived the "ground truth" of Apollo. How well established is this hypothesis?

Don't forget Saturn's thoughtful provision of a marker denoting both its equator and the orbital plane of its family of moons.

Hadn't occurred to me before, Phil, quite how morbid your interests can be. With regard to the demise of MESSENGER, do we know enough about Mercury's gravitational field to be able to estimate how stable the MESSENGER orbit will be? I assume Mercury's gravity is more homogeneous than the Moon's, but perhaps that is counteracted by Solar effects and light pressure?

-Kevin

Perhaps I should have asked the question differently (or, more precisely, asked a different question): when will the ion propulsion be turned off because "we're there!"?

-Kevin

With less than 200 days to go (Vesta or bust!) do we have a precise estimate yet of when orbital insertion will occur? Or is that still remain to be defined/refined? I see nothing more precise than "July 2011" on the Dawn mission website.

-Kevin

Perhaps the most beautiful aspect of this discovery is that it represents one of the greatest triumphs of theory in the last quarter of the 20th century. The theoretical prediction of Io's vulcanism came out in print in Science a week to the day _before_ those op-nav photos were snapped.

Peale, S.J., Cassen, P. and Reynolds, R.T., Science, _203_, 892-894 (Mar 2, 1979)

Melting of Io by Tidal Dissipation

Abstract. The dissipation of tidal energy in Jupiter’s satellite Io is likely to have melted a major fraction of the mass. Consequences of a largely molten interior may be evident in pictures of Io’s surface returned by Voyager 1.

Quoting from the article itself: "The surface of the type of body postulated here has not yet been directly observed, and although the morphology of such a surface cannot be predicted in any detail, one might speculate that widespread and recurrent surface volcanism would occur"

Using the Oppy+landing ellipse image for context (thanks, Centsworth!) I've placed Oppy's route on a pre-landing image showing the putative hematite distribution (warmer colors = more hematite). Looks like we're soon heading for spectrally distinct terrain . Wonder if the "ground truth" will really look any different? Fewer blueberries? Just more dust and duracrust on the ground?

-Kevin

Given that Oppy's the first and so-far only non-Lunar landing mission to every wander beyond its landing ellipse, I'd be curious (pleased) to see a big white line drawn across one of these large-scale route maps. Anyone? Anyone?

(Had to specify "landing" mission as the Venera balloons drifted well outside of their ellipses.)

-Kevin

Some amazing examples of observer bias there. First, what a coincidence that the periapsis of all of the highly eccentric Kuiper belt objects happen to be around the last decade! Must have been some big party in the inner solar system about then. Second, what a sad coincidence that Pluto is moving into the one blank region of the Kuiper belt right about when New Horizons will be winging past.

-Kevin

I take it then that, because the "Approach" vector, the "Sun-Pluto" vector and the "Pluto-Earth" vector are all close enough to parallel that the various eclipses and occultations are not put at risk by the inaccuracies in your knowledge of where Pluto is?

-Kevin

Some of us came of age right smack in the middle of the dark ages; in retrospect this is almost certainly why today I'm a Biochemistry professor and not a planetary astronomer. The rest of you will never truly understand how devastating it was when Mars Observer exploded. May we never go back. Though with the massively inflated budget of MSL threatening Juno (the obligatory outer planets tie in there) and perhaps more, I fear we might.

-Kevin

I asked a mission specialist a few weeks ago and was told that, sadly (my word, not hers), no en route flybys are planned.

-Kevin

Since this is a three body problem (spacecraft, Jupiter, Sun), I believe there is no closed, analytical solution to the problem of finding the best trajectory. I have thus assumed that it is done via Monte Carlo simulations. Alternatively, while there is no analytical solution, there might be good approximations. I'm hoping one of our resident experts will weight in and tell me how slingshot trajectories are calculated, and how computationally intensive the process is.

-Kevin

Five?

-Kevin

True. Pity, though, about that 3 day half-life...

Mercury (the element, not the planet) is nicely volatile, relatively easy to ionize and weights in
at a nice, fat 200 atomic mass units. Unfortunately, though, it's tendency to contaminate surfaces has
precluded its use in ion thrusters.

-Kevin

Fabulous! Despite having spent much time staring at your other (impressively) reprocessed Venera images this is the first time I can get my head around what the view might actually look like. In the interests of verisimilitude I'd love to see the same image with an overlay indicating which portions are "artistic license" rather than simple mathematical reprojections. (Or just lacking the missing pieces of terrain.) On a similar note, how much of the horizon is really captured in those little diagonal strips across the corners of the images?

-Kevin

Until, of course, your eyes melt.

On a more serious note, I've never seen the Venera landing sites pinpointed on the Magellan-based map of Venus. Anyone have any pointers? Heck, for that matter how well is our knowledge of the landing locations constrained? (I don't think Phil-o-vision's gonna help us much this time.)

-Kevin

Alas, solid butane is more dense than liquid ethane. Indeed, most all solid hydrocarbons are more
dense than liquid ethane. No butaneburgs.

-Kevin

Huygens used the comparative brightness of the Sun and Sirus (using a pinhole to reduce the former
and his memory of the latter) and calcualted that Sirus is 27,000AU away (off by a factor of 20, but when you consider
that Sirus is 8x brighter than the Sun -which Huygens couldn't have known- he was only off by a factor of 2.5;
pretty damn impressive). Thus clearly it was known that the Sun is a star prior to the end of
the 17th century. Indeed, the lack of apparent parallax indicated that the stars were very far -and thus
Sun-like in their brightness- well prior to Copernicus. But agreed, it is an interesting question as to who
made the first compelling argument that the Sun is a star.

-Kevin

This argument would fail on more fundamental grounds if there is a physical or chemical imperative that assures that life must arise early in a terrestrial planet's history if it is to arise at all. And there may well be such an imperative. Miller-Urey chemistry, the reactions that produce the likely precursors of life from still simpler atmospheric components, require relatively reducing conditions. But photolysis tends to oxidize planetary atmospheres fairly rapidly (the Earth's geological record seems to rather compellingly suggest that the atmosphere was too oxidized to support M-U chemistry by the time the oldest extant rocks were laid down). Because of this, it seems likely that if life is to happen at all it must start fairly early in a planet's history, and thus the observation that terrestrial life may have arisen effectively simultaneously with the end of the late heavy bombardment (although, as a biochemist, I must admit that I find the evidence for life at 3.8 bya rather underwhelming) cannot be taken as evidence that the formation of life is a likely event.

Tying this back to Titan, am I correct in assuming that the moon's current N2 atmosphere is the product of the photolytic oxidation of ammonia?

-Kevin

With all these wonderful posts showing off very impressive reprocessed Viking image data, this seems like just the right forum to ask if anyone knows how I can get my hands on the raw data from the Viking Biology expts? All I can find on line are scans of busy, poorly drawn graphs. I need the data to generate figures for a book on Astrobiology (it'd be sad if we weren't able to make good figures for the only in situ test for ET that we humans have ever performed). Thanks for any pointers.

-Kevin