by John Rhea
LAUREL, Md. — NASA leaders are once again embroiled in some where-do-we-go-from-here soul searching, where the underlying issue is establishing ground rules for the supporting infrastructure and system architecture to sustain bold ventures into space.
Once accomplishing that — and they already have identified a list of potential generic missions — NASA officials will take a hard look at the enabling technologies necessary to go forward. Then they will ask the electronics industry to join the party; now is a good time to get ready.
In true industry road-map fashion, Ralph McNutt, a space scientist at the Applied Physics Laboratory of Johns Hopkins University in Baltimore, starts with the desired system architecture so that all the participants can begin identifying the technology drivers. "Some will be there on time," he says. "Some won`t."
His candidate is a spacecraft available for travel outside the Solar System after 2020. It will weigh no more than 110 pounds, can launch on Delta 3-class rockets, operate at temperatures of 100 Kelvin, and have autonomous software and an optical downlink. This system architecture, of course, must be sufficiently adaptable to accommodate several different kinds of missions.
McNutt participated in a NASA strategic planning exercise that began last month to prioritize these missions. In the keynote address at this year`s Military and Aerospace Applications of Programmable Devices and Technologies conference in September, he urged attendees to start preparing now for what the future will require. This is what NASA Administrator Daniel Goldin calls the grand challenge of delivering new scientific revelations that taxpayers will support. The conference was at the Kossiakoff Conference Center of the Applied Physics Lab.
There are really only three categories of things to do in space:
- commercial activities, such as communications, meteorology, earth observations, and navigation;
- their military equivalents (frequently initiated by the military); and
- science involving in-situ measurements and using space as an observation point.
NASA has already handed the first category over to private business, and the military is increasingly relying on commercial resources. By the process of elimination, that leaves space science as NASA`s next grand challenge.
The NASA study, known as the origins program, has boiled space science down into two questions, according to McNutt:
1) What is the nature of the galaxies and the stars; and
2) Are we alone?
The first question includes studying the interaction of the solar wind, which begins about 9.3 billion miles from the Solar System. This also amounts to 100 Astronomical Units, or AU, away from the Solar System. An AU is the distance from the sun to the earth, or about 93 million miles. The second involves looking for organic materials in our own Solar System (notably the Jovian moon Europa) and possible habitable planets around other stars.
Exploring beyond the Solar System, an idea I timorously tried to resurrect recently, turns out not to be as challenging as is generally believed. The Voyager 1 spacecraft, launched in 1977, has already reached a distance of 70 AU and continues to recede at 3.6 AU a year. Voyager 1, in fact, passed Pioneer 10, launched in 1972, in September. Moreover, an Interstellar Monitoring Probe launched in 1973 into Earth orbit is still working.
Now NASA experts are looking for a spacecraft to reach out 300 to 500 AU at a velocity of 20 AU a year and built to last at least 50 years. That`s still a long way from Alpha Centauri — the next-closest star to Earth after our own sun — but McNutt has a list of more immediate questions for the spacecraft to ask: What are the interstellar magnetic fields like? The interstellar dust? Low energy cosmic rays? How ionized is interstellar space? Are there any troublesome supernovas in our galactic neighborhood?
To achieve those speeds and distances, NASA scientists will need a combination of new propulsion and other supporting technologies. A start on the problem is to send a spacecraft around the sun to pick up what is called a gravity assist. In fact, NASA is planning to launch a solar probe to within four solar radii in 2007. This would be a good trajectory for the initial phase of an interstellar probe, but McNutt estimates additional propulsion will be necessary to pick up another nine miles per second. This is beyond today`s chemical propulsion technology and will require some combination of nuclear and electric means, he says.
In the category of trying to find out if we`re alone, another proposal before the study group is a space-based interferometer to look for habitable planets out to a distance of 40 light years. This would involve five spacecraft widely dispersed in earth orbit, each with four 8-meter telescopes. The electronics task to integrate and analyze the inputs would, to say the least, be challenging.
The infrastructure issue boils down to justifying the huge capital investments necessary up front for any bold ventures into space. While the crystal ball gazers of the 1940s and 1950s generally agreed that large manned missions, including space stations, would be the logical direction, the reality was otherwise. Instead, many small unmanned instrument probes went to the nearby planets, while U.S. and Soviet astronauts raced for the moon during the Cold War. With the completion of the Apollo program, the emphasis logically turned to low-cost reusable vehicles, such as the space shuttle.
During the last major NASA planning effort in 1975, scientists proposed obtaining samples of particularly inhospitable Venus, as well as the nucleus of a comet. Those missions are still on the books, McNutt notes. Out of that planning exercise also evolved ideas for the industrialization of space (perhaps to be accomplished with the International Space Station), exploitation of space resources, deep space probes, space telescopes (realized with the Hubble space telescope), and even, perhaps farthest out of all, space tourism.
In 1926 the great Russian theoretician, Konstantin Tsiolkovsky, outlined a 16-step program leading up to a galactic human civilization. Industry road maps hadn`t been invented in those days, so he didn`t feel compelled to put dates on his 16 steps. Nonetheless, implicit in his thinking about future exploration of space was the hope that where machines go first, humans will follow.
International competition will no longer sustain public support, and profitable exploitation of space resources will eventually be necessary. An idea that McNutt and others floated is to leave room in the infrastructure and system architecture to be firmed up now for Antarctica-type visits in preparation for future human presence and resource exploitation.
That`s the issue of the moment: agreeing on the ground rules so industry can get on with the job of creating the enabling technologies. A useful complementary step might be to begin now to identify those technologies.
That`s the issue of the moment: agreeing on the ground rules so industry can get on with the job of creating the enabling technologies. A useful complementary step might be to begin now to identify those technologies.
