The Challenge of Spacecraft Robotics

Is any unmanned spacecraft a robotic probe? You might think so, given the tasks the hardware has to perform to accomplish a given scientific mission, but a more precise definition came out of the European Space Agency’s ASTRA 2004 workshop, held in the Netherlands early in November. Says Gianfranco Visentin, head of ESA’s Automation and Robotics Section, a space robot is “…a system having mobility and the ability to manipulate objects plus the flexibility to perform any combination of these tasks autonomously or by remote control.”

And according to this ESA press release, spacecraft robotics should be able to achieve the following:

  • withstand a launch
  • operate under difficult environmental conditions often in remote locations
  • weigh as little as possible as any mass is expensive to launch
  • use little power and have a long operational life
  • operate autonomously
  • be extremely reliable
  • We’re gaining a lot of experience with robots through the use of machines like NASA’s Mars rovers Spirit and Opportunity, which continue to set records for longevity and scientific discovery on the Red Planet. ESA’s own Aramies/Scorpion robot is an eight-legged rover that may go NASA one better, by providing a range of motion that can help it operate in extremely rugged terrain.

    ESA rover at workBut the problems faced by all space robotics are amplified hugely when we start talking about the long time frames demanded of interstellar missions. Even a forty-year journey to the Oort Cloud, which is about as far as we can reasonably extrapolate a mission we could design in the near future, would involve issues like radiation, which can cause errant behavior in electronic systems, even those specifically hardened for the environment. Thermal conditions test the mettle of any spacecraft, and communications delays make increasing autonomy essential. A probe in orbit around Centauri A would face an 8.6 year round-trip communications delay; autonomy thus becomes the sine qua non of any true interstellar attempt.

    Image: The Aramies/Scorpion robot is being developed for ESA by the University of Bremen. Credit: University of Bremen

    “We are continuing,” says Visentin, “to do research into new types of robots which can cope with the special conditions in space, go where humans cannot and help astronauts manage the huge amount of work on the International Space Station.” All of which needs to be supplemented in the area of long-life electronics, redundancy, radiation hardening and artificial intelligence, a huge wish list that, just as much as the propulsion conundrum, could make interstellar robotic probes the driver for advances across the technological spectrum.

    Three Space Pioneers Discuss Their Trade

    I’ve run into a fascinating discussion on American Enterprise Online titled “Look Heavenward?” — it’s a collection of articles whose description on the magazine’s table of contents, “The pros and cons of spending more on manned space exploration,” is wildly insufficient to describe its range. The most interesting of the pieces here consists of three thought-provoking conversations with space and astronomy pioneers. Bill Kauffman interviews comet hunter David Levy; David Isaac talks to Mars Society president Robert Zubrin; and Frederick Turner (University of Texas at Dallas poet and sometime interstellar theorist), interviews Freeman Dyson. I’ll run just a few snippets, but at some point be sure to read the whole piece here.

    From the Zubrin interview, discussing terraforming and how humans may adapt to other worlds:

    ZUBRIN: I can elaborate by analogy. Human beings are not native to the Earth. We’re native to East Africa. We’re tropical animals. We have long, thin arms with no fur on them. No human could survive a single winter night here in Colorado without technology.

    But then around 50,000 years ago, people started migrating from Africa to Europe and Asia, right into the teeth of the Ice Age. To survive in the winter you had to engage in ice fishing or big-game hunting, both of which are very complex activities. Humanity transformed itself radically from this East African being to homo technologicus, the creature who can cope with all sorts of novel environments through technological creation. That is the basis on which we became a global species.

    We go to places like Mars, which are perhaps comparatively hostile to us in the way that Europe was to early tropical man. But we figure out how to address that. Ultimately it leads to the creation of a human story that is richer and vaster in its possibilities. Human societies on thousands of planets orbiting thousands of stars in this region of the galaxy. Innumerable social forms and vast arrays of technologies that are as yet unconceived. A profusion of artistic creation and literatures. So yes, a new type of human civilization. That’s the stakes.

    Mars is the critical test that will determine whether we become a spacefaring species or whether we continue to be limited to Earth. That’s why humans-to-Mars is the most important thing that our society will do when viewed from the future. It’s going to be risky when people go to Mars for the first time. But nothing great in human history has ever been accomplished without courage.

    And here’s Freeman Dyson, asked whether science is incompatible with religion:

    DYSON: For me personally, religion is a willingness to accept mystery. Most of the important questions are mysteries which we shall never solve, and the purpose and meaning of life is just one of those. Religion in that sense is a way of life, and it has a great deal of meaning.

    TAE: At the age of eight, I had a realization of the beauty and the incredible elaboration of nature. I’ve never really gotten over that feeling that the whole of life is miraculous, from beginning to end. This piece of biochemistry actually has a soul. It seems to me that the world means something.

    DYSON: I absolutely agree with that. Whatever you learn from science doesn’t contradict that. In fact, it only makes it more miraculous.

    TAE: There are differences among scientists, aren’t there? A lot of physicists, even if they don’t particularly believe in God themselves, almost find it necessary to postulate God in order to be able to do physics: Einstein talking about God playing dice, Hawking talking about what’s in God’s mind, Rutherford saying that the universe is like a gigantic thought more than like a gigantic machine, and so on. Biologists, on the other hand, in order to be able to do evolutionary biology, feel the need to take it as a principle that there is no creator.

    DYSON: Right. Biologists are much more hostile to religion than physicists, and I think needlessly so. They create this opposition to science by being so dogmatic. It certainly is true that if you are a physicist, you are familiar with the fact that things are not machines. They don’t follow predestined tracks. All the time we are making random choices. It’s just a totally different way of looking at things from these ball and stick models that the biologists use.

    TAE: So you’re not a determinist?

    DYSON: You can’t be. Physics tells you quite clearly that randomness is built into nature.

    Centauri Dreams note: Those unfamiliar with interviewer Frederick Turner should seek out his “Worlds Without Ends,” which ran in Reason back in June of 1996 (Vol. 28, Issue 2). It’s a remarkable article about the rationale for space exploration that avoids cliches of any sort and advances a startling theory about the real economics of interstellar voyaging. I’ll run a quote or two from Turner’s piece on Saturday.

    And finally, from Bill Kauffman’s interview with David Levy, this little gem about really seeing what you’re looking at:

    I went to an observatory just east of here, on Mt. Graham, and I spoke to a graduate student who was using this enormous telescope. I said, “What are you observing?” She said, “I’m observing this variable star,” and she gave me its number. I said, “Do you know what constellation it’s in?” She didn’t. I said oh, that’s in the Taurus Milky Way! But she didn’t know the magic. Bart Bok, one of the greatest astronomers of the twentieth century, said, “When you are in an observatory at three o’clock in the morning, stop your photograph. Stop your photometer. Walk away from the telescope. Walk down the stairs. Walk out the front door. Now walk 20 paces, no more, no less. Then stop–and look up at the stars–just to make sure you are making bloody sense.”

    On Colonizing the Galaxy

    Freeman DysonFrom the polymath Freeman Dyson, in an essay called “Extraterrestrials,” which appears in his collection Disturbing the Universe (New York: Harper & Row, 1979, pp. 210-211):

    “Given plenty of time, there are few limits to what a technological society can do. Take first the question of colonization. Interstellar distances look forbiddingly large to human colonists, since we think in terms of our short human lifetime. In one man’s lifetime we cannot go very far. But a long-lived society will not be limited by a human lifetime. If we assume only a modest speed of travel, say one hundredth of the speed of light, an entire galaxy can be colonized from end to end within ten million years. A speed of one percent of light velocity could be reached by a spaceship with nuclear propulsion, even using our present primitive technology. So the problem of colonization is a problem of biology and not of physics. The colonists may be long-lived creatures in whose sight a thousand years are but as yesterday, or they may have mastered the technique of putting themselves into cold storage for the duration of their voyage. In any case, interstellar distances are no barrier to a species which has millions of years at its disposal. If we assume, as seems to be probable, that advances in physical technology will allow ships to reach one half of light velocity, then inter-galactic distances are no barrier either. A society pressing colonization to the limits of the possible will be able to reach and exploit all the resources of a galaxy, and perhaps of many galaxies.”

    Proto-Earths May Be Abundant

    New infrared studies of the dust around three young stars lend credence to the idea that Earth-like planets may circle other stars. Using the European Southern Observatory’s Very Large Telescope Interferometer (VLTI), a team of astronomers studied the proto-planetary disks around the stars, homing in on the inner region of the discs. The results: the inner discs, in the area analogous to that swept out by the Earth around the Sun, are loaded with crystalline silicate grains — sand — with an average diameter of about 0.001 mm. Much smaller grains (about 0.0001 mm in size) would have contributed to the creation of this material, being heated in the inner system near the young star and coagulating into larger grains in this dense region.

    From an ESO press release:

    An important conclusion from the VLTI observations is therefore that the building blocks for Earth-like planets are present in circumstellar discs from the very start. This is of great importance as it indicates that planets of the terrestrial (rocky) type like the Earth are most probably quite common in planetary systems, also outside the solar system.

    Says Dutch astronomer Rens Waters:

    “With all the ingredients in place and the formation of larger grains from dust already started, the formation of bigger and bigger chunks of stone and, finally, Earth-like planets from these discs is almost unavoidable!”

    Interferometry — combining the light from multiple telescopes — allows VLTI to offer a hundred-fold increase in angular resolution over previous studies, rendering the infrared spectra around the stars HD 144432, HD 163296 and HD 142527 in unprecedented detail. The VLTI is an array of four 8.2-meter telescopes (the VLT itself) that are being supplemented with four movable 1.8-meter auxiliary telescopes that can be moved along a grid of railroad tracks. The team used two of the 8.2-meter telescopes a hundred meters apart for its observations. The entire array is installed at the Paranal Observatory in Chile’s Atacama Desert.

    The team’s results appear in more detail in Roy van Boekel et al., “The building blocks of planets within the ‘terrestrial’ region of protoplanetary disks” (Nature, November 25, 2004). Image credit (above): European Southern Observatory.

    Tracking Near-Earth Asteroids

    An asteroid called 2004 TP1 came within 13 LD of Earth on November 2 — LD stands for ‘lunar distance,’ and is the average distance between the Earth and the Moon (238,855 miles, or 384,401 kilometers). Asteroid 2004 RZ164 will come even closer, at 7 LD on December 8. Both objects are considered Potentially Hazardous Asteroids (PHAs, as acronym-obsessed scientists like to call them). That means they are larger than 100 meters in diameter and come too close to Earth for comfort.

    653 Potentially Hazardous Asteroids are now known. We’ve discussed such objects as perhaps the most significant reason for building up a space-based infrastructure that could ward off a potential strike. A good place to track them is the NASA-sponsored site, which bills itself as ‘News and Information about the Sun-Earth Environment.’ The site likewise tracks solar wind conditions (currently moving at 493.7 kilometers per second, based on data transmitted from the Advanced Composition Explorer spacecraft at the L1 point between Earth and the Sun). Also available at news of auroras, meteor showers, solar flares, and NOAA forecasts of the probability of geomagnetic storms.