JPL and NASA News

With the successful launch of the Russian service module Zvezda and its remote-controlled docking with the initial two modules  of the ISS in late July,   a logjam has broken, and an exciting schedule of further launches and   assembly is in store for the next year. Of course, in the short term, the most important effect of the ISS  on astronomy may be the interference of yet another very bright artificial object in the night sky, affecting observing sites practically worldwide. But from a broader point of view, the relationship of the ISS to astronomy, and indeed to science, is a bit  tenuous, and indeed quite controversial in the USA, where it is widely seen as  a boondoggle, taking money from "real science" to serve the engineers and the  institutional needs of NASA. While the financial drain is beyond arguing, it is a sad fact that pure science, as an abstract intellectual enterprise, does not have much of a constituency in the US, nor probably worldwide. Of course everyone wants science to cure cancer, raise their standard of  living with neat gadgets, or increase prosperity with new jobs and productivity, but that's all applied. While I have always made my living in basic research,  I have mostly not seen the space program as primarily driven by the values of academic science. The most spectacular example is the old Apollo Moon Program. We would never have spent $24 billion in 1960s dollars, for example,  in order to  understand the origin of the Moon -- the very idea is ludicrous. Yet the Apollo Program was in fact a bonanza for science, and did lead to a much deeper understanding of the history of the Moon and of planetology generally.

Similarly with the station, although NASA's nominal justification for it  is mostly in terms of science, applied or basic. Instead, I see it as part of NASA's larger goal of supporting human exploration and expansion into space, and as such it creates its own enthusiasm and  financial resources, different and larger than anything scholarly research  could ever command. Being myself very enthusiastic about those larger goals,  I am just happy that the pursuit of them also opens up opportunities, ecological niches, for astronomy and the other sciences.   Parasitic science, if you will. In any event, I hope that the experience gained on the station will allow us to gain an increasing facility in operations in this strange new environment, so that eventually we will be able to undertake projects and programs that cannot be realistically considered today, and that the benefits will be felt  in radical and unforeseen ways across the entire spectrum of human activities, from the economic and environmental, to the philosophical and cultural,  to the purely scientific.

At this writing, space shuttle Atlantis is on KSC Pad 39B,  being prepared for launch to the ISS on September 8, for an 11-day, seven-person logistics mission with supplies and equipment needed prior to the arrival of the first crew, scheduled for November. A Russian Progress supply vehicle docked with the ISS on August 8, and boosted it to a slightly higher orbit. It is the first of many such Progress supply missions, which together make up a large part of the Russian contribution to the ISS project. The next assembly mission, scheduled for October 5 by shuttle Discovery, is   to deliver the so-called Z1 truss and PMA-3 Pressurized Mating Adapter, plus Ku band communications equipment and Control Moment Gyros (CMGs). Unfortunately at the moment there is a problem in the CMG unit, which may delay the flight; or may well have been resolved by the time you read this. "CMG" is NASA-speak for a system of massive flywheels, with their axes oriented in different directions. By spinning the wheels faster or slower, the attached spacecraft can be reoriented in space without the need for the expenditure of any precious reaction control propellant. Then, if the CMG problem is resolved, and after the launch of the first crew aboard a Russian Soyuz on October 30, the space Shuttle Endeavor will arrive around the end of November for the next assembly flight,  with the first big cargo of solar arrays, photovoltaic converters,   and radiators.  The solar arrays are the first of four huge modules which will dominate the visual appearance of the completed station. Since the long truss where they will finally be mounted is not yet installed, they will temporarily go on the Z1 truss brought up in October.

All this is quite confusing without a long series of assembly diagrams to show what goes where. Also, since the potential for problems and delays, leading to adjustments in the  schedule, are inevitably large in a project of this magnitude and complexity, it does not seem very useful to report in detail on the launch manifest  many months in advance. Fortunately, NASA has recently reorganized its ISS web pages, and now provides several terrific facilities for keeping up with the show. At the ISS Assembly page, http://spaceflight.nasa.gov/station/assembly/index.html, is a link to a current table of the ISS flights in store,  with further links to a page for each flight that features  nice pictures of the assembly at corresponding stage. There is also link to a good video clip of the entire assembly, which can be stepped through slowly and examined at each stage. Finally, the Russian Space Agency and the US company Eastman Kodak have also announced that they will provide free live coverage   in still and video form of the ISS assembly in real time over the Internet, worldwide, using Kodak digital cameras mounted inside and outside the new Zvezda service module. The cameras will be delivered on a future space shuttle flight.

Mars Program

After a difficult review of months duration, necessitated by the many questions raised after the  wrenching disasters that befell the 1998-1999 Mars missions, NASA has decided to proceed with two identical rovers for the 2003 launch  opportunity. You may recall that the old plan, described here in May 1999,  featured both an orbiter and a lander for each of the next few opportunities.  Recall also that launch opportunities occur a few months before oppositions (thus every 2 years and 7 weeks, on the average), with the next ones after 1999 being in 2001 and 2003. The old program was modified in May 2000  after the December 1999 loss of Mars Polar Lander,  by canceling the 2001 lander,  but leaving the corresponding 2001 orbiter mission in place. That decision left open what to do about 2003, the next opportunity, also nominally scheduled for both a lander and an orbiter.

The surviving Mars Surveyor 2001 orbiter mission is scheduled for launch  on 4 April 2001, and will arrive on 20 October. After a 76-day period of aerobraking to achieve a low-altitude 2-hour orbit, the scientific part of the mission will begin. Three instruments will be aboard.  THEMIS, a THermal EMission Imaging System, will provide both a high-resolution camera and an infrared spectrometer to map surface mineralogy. A Gamma-Ray Spectrometer (GRS) will map the surface elemental composition and detect water or ice to a depth of many  centimeters. And MARIE, the Mars Radiation Environment Experiment, will help determine the surface radiation risks for future human explorers. The spacecraft will also be equipped to serve as an Earth-relay for communications with future Mars craft, either landing, orbiting, or on the surface. Lack of such communications was a significant factor obscuring the fate of the Mars Polar Lander, which simply disappeared behind the planet and was never heard from again.

The new 2003 missions will feature identical landers based on the highly   successful 1997 Pathfinder airbag system,  with greatly enlarged rovers, each about the size of a golf cart,  and roughly 110 kgm in mass. They will be particularly intended to follow up on the Mars Global Surveyor discovery that substantial quantities of liquid water seem to have been released onto the surface in geologically recent times.  If so, then water is probably still present underground today. This would greatly increase the likelihood of finding Martian microorganisms,  either fossil or even, just possibly, still living. The realization that a vast population of microorganisms lives deep underground on Earth in rocks, plus the new understanding that a large quantity of material  must have been exchanged between Mars and Earth due to ejecta from asteroidal impacts early in the history of the Solar System, yet after    terrestrial life seems already to have existed,  are important elements in the recent increase in interest about the prospects for Martian life.

The two new rovers  will be far more capable than the Pathfinder rover, which was forced to communicate with Earth through its immobile ground station,  and was therefore not able to venture far from it. The new missions will dispense with the old Pathfinder ground station, and  the rovers will have the capability for direct communication with Earth at high bit-rate, or via the 2001 orbiter as a relay. They will also be able to move about 100 m per day (roughly the total  distance the old Pathfinder rover moved during its entire life), and should last for at least 90 days.

The missions will be launched on Delta 2 rockets for a total cost of about $600 million, of which two-thirds will be for the first. While the second mission comes at a bargain price, the total is still a large sum by recent faster-better-cheaper standards.   NASA's willingness to undertake such an ambitious project is a clear sign of the growing scientific excitement about the prospects for life on Mars, and a good omen for the future of Mars exploration. Rumors that a financial crunch would necessitate canceling other planned  missions, in particular the Pluto/Kuiper Express, have not been   confirmed so far.

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