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MarsWatch

1998-1999 Apparition

Linking Amateur and Professional Mars Observing Communities.

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The International MarsWatch Electronic Newsletter


Volume 3; Issue 1
November 22, 1997
Circulation: 1750

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Dear Marswatch participant,

Resurrected from the ashes, here is the latest installment of what will hopefully be a much more regular distribution of the MarsWatch electronic newsletter. Primary responsibility for compiling the latest and greatest information on Mars has now been taken over by A.L.P.O. Mars recorders Dan Joyce and Dan Troiani. Their first contribution is provided below. Thanks, Dans!

I will continue to maintain the email distribution list as well as the various Cornell and JPL Marswatch-related WWW archives. If you are receiving duplicate copies of this mailing, or you want your name removed from the distribution list, please send me email.

--Jim Bell
Cornell University

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MarsWatch News: November 1997

Compiled by Dan Joyce (djoyce@triton.cc.il.us) and Dan Troiani (dtroiani@triton.cc.il.us)
Association of Lunar and Planetary Observers

Poor little Pathfinder! The Sagan Memorial Station has gone dormant, not unexpectedly; and NASA plans to continue trying about every two weeks to revive it, but hope is fading that its batteries will once again prove strong enough to enable significant communication with earth. Despite its success, having sent back wondrous images of Ares Vallis both from the mother craft and its little sidekick Sojourner for about three times longer than anticipated, there is somehow a feeling of regret that this improbably popular denizen of cyberspace will just be a memory.

It may be how striking the panoramic vistas were, how mesmerizing the 3-D effect was, how cleverly the rocks and features were named or even how resourcefully this machine was placed on the surface that conjures up the affection we all felt for it. Maybe it was just how small, yet how efficient, this marvel of engineering was, especially that diminutive and highly acrobatic rover, that caught our collective fancy. Yet, maybe it was really because the place that it landed on was the planet of intrigue, the one that inspires the most excitement, and perhaps even to this day a little apprehension, that was its charm. (Probably, for the budget-beleaguered and stressed-out government, it was the relatively low price tag for the mission!)

Even a telescope optical technician can appreciate what the mission found there; Martian dust was found to be one micron per grain on average, perfect for the pre-polish stage! And dust devils may be a leading mechanism for mixing dust into the atmosphere, adding a meteorological touch to the overall scheme. There were surprises to be found in the Martian atmosphere and even some unexpected results of soil/rock content; sand was apparent. Verification of the suspected watery nature of the Martian remote past was garnered very quickly. The excitement of Pathfinder combined with the results of the study of meteorite ALH84001 one year earlier, have renewed the concept of life on Mars, including the concept that some microbials may yet be found underground somewhere at Mars. It all represents a very great challenge for us to find convincing evidence of either their presence or absence.

Congratulations are in order to Project Manager Brian Muirhead, Mission Manager Richard Cook, JPL Director Ed Stone, NASA Administrator Dan Goldin and the entire Pathfinder team for an inspirational effort and the incentive to look forward to future missions of this nature.

Speaking of future missions, one is at hand: The Mars Global Surveyor mission, already in orbit around the planet, can be considered a great success prior to the official commencement of operations! Despite unexpected difficulties, it has relayed to earth images of extraordinary resolution, probably close to twenty-five times greater than the Viking orbiters. One of its solar panels is apparently hanging more loosely to the spacecraft than originally anticipated, and the Martian atmosphere has greater extent above the surface than had been thought, so the planned aerobraking maneuvers to circularize the orbit have had to be scaled back enough to delay the onset of systematic coverage. There is apparently too much risk of spacecraft destabilization should steep aerobraking continue, so only very shallow, time-consuming and closely monitored deceleration is being attempted. This means that the planned March initiation of its main task will be delayed about a year. The downside of this is that A.L.P.O.'s carefully prepared sequence of anticipated events for Surveyor to watch for, which was presented at the Mars Telescopic Observations Workshop in Tucson (AZ) in October, will have to be revised, and in so doing eliminating some important, eagerly awaited confirmation of activity which may now have to be covered by a subsequent mission. On the plus side is the fact that Mars will be nearing opposition by the time the mission is in full gear, so we will be able to conduct meaningful contemporaneous observations. This may at first appear to be without merit, or nearly so, given the staggering degree of resolution its cameras will have compared to anything earth-based; but at least we can spot a transient event which may affect its ability to obtain imagery such as clouds or dust. And what it can see in extreme close-up may have profound import for interpretation of what we see on the scales we are used to, but only if we are in fact looking.

Speaking of the Mars Telescopic Observations Workshop II, there is nothing like Tucson and vicinity during the dark-of-the-moon phases to provide just the right atmosphere for a conference. Jim Bell, Ann Sprague and their colleagues brought together nearly forty of us from around the world (Germany, Japan, Belgium and England were represented) to present our data and, even at the risk of being a bit raucous, speculate about what could be construed from it. There was widespread acceptance of the work of skilled amateur astronomers and considerable discussion of the application of the observations we have provided. Particularly graphic was the high resolution video of the dust activity of the 1990 apparition taken by Don Parker with his 16" f/6 Newtonian which so closely resembled the Hubble images of last June, showing dust between Chryse and Valles Marineris and suggesting that at least some dust might encroach upon the Pathfinder site, which in fact occurred. Dan Troiani had, after a thorough review of observations from ALPO Mars Section archives centered on the Martian season at the time of the landing, passed along his prediction that dust would be a factor at the Ares Vallis site at the time of the mission's commencement to Jim Bell, our science adviser and mission team member, about eight months earlier. Nice goin', Dan, and we're all glad there were no ill effects on the spacecraft.

Concerning dust, though, once again it was emphasized that a red filter is most appropriate for visual observations as well as imagery - the concept of a "yellow cloud" being associated with dust is being heavily downplayed. "WHAT DOESN'T LOOK BRIGHT IN YELLOW LIGHT?" was the oft-heard query. Still, the jury may yet be out as to whether SOME dust on Mars may be more apparent with a yellow filter, comparisons between the colors probably ought to be made, especially if video is the medium, by as many observers as possible during the 1999 apparition, especially given the closer proximity to dust season that Mars will be approaching at that time. There was considerable discussion that ordinary clouds, those that appear conspicuous in shorter wavelengths, that were still bright in red light during later stages of the 1996-97 apparition may have had a high level of dust saturation. This had been noted during the 1992-93 apparition as well, and the correlation, based on the sum of other data, including the spectacular dust cloud data set compiled by B.A.A. Mars Section leader Richard McKim, now seems more conclusive.

Deep down, it seemed that the workshop participants were somehow aware that their work is really an important resource for scientists planning missions to Mars - and one could not help sense that this would include the possibility of manned flights whether we are ready for them or not. In the back of everyone's mind is the incentive for such ambition brought about by that ALH84001 meteorite and even the very popularity of the Pathfinder internet site (well over a half a billion hits!). Obviously, more needs to be done; but it now appears that in fact the groundwork has been laid and that we can build on that.

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Jim Bell will continue to maintain the email distribution list as well as the various Cornell and JPL Marswatch-related WWW archives. If you are receiving duplicate copies of the International MarsWatch Electronic Newsletter, or you want your name added to or removed from the distribution list, please send him an email at jimbo@marswatch.tn.cornell.edu.

Jim Bell
Cornell University
Department of Astronomy
Center for Radiophysics and Space Research
424 Space Sciences Building
Ithaca, NY 14853-6801
Phone: 607-255-5911; fax: 607-255-9002
Email: jimbo@marswatch.tn.cornell.edu
WWW: http://marswatch.tn.cornell.edu


Read the Next MarsWatch Newsletter (Volume 3; Issue 2; December 2, 1997)

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This page is maintained by David Knighton for the International MarsWatch. The 1998-1999 MarsWatch site it hosted by the Astronomical League as a service to the astronomical community. Comments, corrections, and suggestions can be addressed to webmaster@astroleague.org. This page last updated December 28, 1998.