A swarm of cunning robots - some only several inches wide - soon
may swarm, float, walk, swim, fly, creep, burrow and hop across the
alien worlds of the solar system.
Two summers ago, the world thrilled to the sight of a
skateboard-size Mars robot, Sojourner, venturing like an excited
puppy around the Red Planet, "sniffing" soil and bumping into rocks.
But Sojourner looks like a lazy pooch compared to NASA's
futuristic robo-critters, including:
*A four-legged robot the size of a cigar box that will hop around
an asteroid like a grasshopper.
*A snakelike tube that will drill thousands of feet into the
Martian crust, seeking subsurface water and, perhaps, microbes.
*A two-legged "walking" robot under development at NASA's Ames
Research Center in Mountain View.
*A hot-air balloon with TV cameras that would bob through the
atmosphere of the giant planet Jupiter. It would pass above and
survey multicolored mega-hurricanes bigger than Earth.
*Mini- "helicopters" able to maneuver through the Martian
*A robotic "submarine" that would plunge into an icy ocean on
Europa, a moon of Jupiter, and seek weird life forms in its dark
AH: Smaller, cheaper, faster <
Some of the robots would be far smaller than today's space
probes. The drive toward smaller robotic probes is part of NASA
Administrator Daniel Goldin's push for "smaller, cheaper, faster"
missions to get the biggest bang out of the ever-diminishing
post-Cold War NASA budget.
The lighter the payload, the lower the cost of launch, says Brian
Wilcox, supervisor of the robot vehicles group at Jet Propulsion
Laboratory in Pasadena.
"Mass reduction is very important because of the cost of the
launch vehicle," he says. "The cost of a Delta launch vehicle is
about $60 million."
Ironically, such cost-saving micro-gadgetry is potentially
threatened by a recent proposed cut to NASA's budget. On July 30,
the House Appropriations Committee voted to cut NASA's space science
budget for fiscal year 2000 by 8 percent, or $164 million, and the
overall NASA budget by 7 percent, $12.7 billion, compared to current
The cuts to robotic research and other space science projects
"from a scientific point of view would be devastating," says Peter
Norvig of Ames. He runs the lab's computational science division,
which oversees robotic development at the Mountain View facility.
The final fate of NASA space science is uncertain "until the
Senate acts and until this budget impasse between the Congress and
administration gets settled. Gosh knows where it's going to end up,"
says Louis Friedman, executive director of the Pasadena-based
Planetary Society. Co-founded by the late Carl Sagan, the society is
the nation's leading pro-space lobbying group and has 100,000
members; it is leading a national fight to salvage the NASA budget.
AH: Enter the nanobots <
If NASA's robotic program survives the budget cuts, a new breed
of "astronauts" will soar skyward in the next decade or two -
astronauts made of metal and microchips, and as small as cigar boxes
or smaller. Because of their diminutive size, they have been dubbed
"nanobots." ( "Nano" is the scientific prefix that refers to
billionths of something. For example, a nanometer is a billionth of
Conceivably, NASA could cram numerous nanobots aboard a single
launch vehicle, then send them to Mars or another world. There, they
would disembark and form a "robot colony," in the words of Ames
systems engineer Hamid Berenji.
The colony could scout out in different directions to survey the
entire planet. Such fleets would be mechanical versions of the great
human terrestrial exploring teams of the past, such as Lewis and
At Ames, Berenji and biomechanical-electronics engineer Ron
Jacobs are developing a two-legged robot that walks with a normal
walking motion. It could navigate over rough terrain, such as the
rock-strewn, crater-scarred surface of Mars.
Berenji and Jacobs work for a NASA contractor, Intelligent
Inference Systems Corp. of Sunnyvale.
Ames researchers are developing a spherical robot that can float
aboard a spaceship and fly around, propelled by small propellers.
Its purpose: to allow a busy astronaut to check on an experiment in
another lab, or a potentially dangerous situation - say, a gas leak
- without getting directly in harm's way.
Originally, Norvig says, it was called the Personal Satellite
Assistant, "but no one liked that name." So they renamed it the
Spacecraft Micro-Robot, although some Ames researchers have
nicknamed it "S2D2" or Space Shuttle Digital Droid in honor of the
doughty fictional robot R2D2 of the film "Star Wars."
For sheer cuteness, none of the proposed nanorobots can rival a
"hopping" robot under development at JPL. It's part of a joint
U.S.-Japan space mission scheduled for launch aboard a Japanese
rocket to an asteroid in July 2002.
The asteroid is so small - the diameter of six football fields -
that it has very low gravity, about 1 / 100,000ths that of Earth.
The robot will have to move very gingerly about its surface, lest it
accelerate to so high a speed that it escapes into space. "Escape
velocity" for the asteroid is 3 feet per second (compared to several
miles per second for Earth). That's about strolling pace for a
The nanobot would "hop" by gently compressing its
"legs" together, allowing it to "spring" upward at a speed of 8
inches per second.
"We could hop 100 or more meters (more than 300 feet) into the
sky," Wilcox says.
AH: Chill factor <
Nanobots would have an inherent disadvantage: They get cold
easily. A well-known principle of physics is that smaller objects
cool off faster than large ones, because the smaller object's
surface is bigger relative to its overall volume than a larger
object's. (This is one reason why small planets like Mars apparently
have no active volcanoes: Their internal heat escaped to space long
And the nanobot will be too small to carry an on-board heater.
Scientists could give it heat shields to keep it warm (as well as to
protect it from high-speed interstellar particles called galactic
cosmic rays), but the added weight of shielding would obviate the
advantage of its small size.
So the JPL team is trying to develop nanobots whose electronics
can endure the temperature extremes of deep space - which range from
boiling-hot daytimes to nighttime temperatures about 300 degrees
below zero Fahrenheit, far colder than the South Pole.
On Thursday, NASA announced plans to launch into Earth orbit
three small satellites, dubbed the "Nanosat Constellation
Trailblazer" mission. Each satellite would be an octagon 8 inches
high and 16 inches long. Among other things, the minisatellites - to
be launched in 2003 - will test the ability of new electronics and
other equipment to survive "near the boundary of Earth's protective
magnetic field," agency spokesman Donald Savage said.
Robotic balloons or "aerobots" are also under development. These
could float through the atmospheres of Mars, Venus, Jupiter and
Titan, a moon of the ringed planet Saturn.
JPL scientists are designing a Venusian aerobot that would float
more than 30 miles above the searing-hot planet. The probe would
drop TV-equipped instruments or
"sondes" toward the surface, snapping pictures as they dropped
toward the surface, which is typically veiled by an extremely dense
Another possibility is a balloon that would periodically lower
its instruments to the Venusian surface, briefly take measurements,
and intermittently rise to cool off. Otherwise the instruments would
melt on the extremely hot surface, which, according to JPL's Jim
Cutts, is hot enough to melt lead.
In one daring mission, a balloon would lower toward the Venusian
surface, allowing the robot to gather rock samples. Then the balloon
and robot would rise into the sky, where an on-board rocket would
fire the rock samples into orbit. There it would rendezvous with
another rocket, which would ferry the samples to Earth.
AH: Atmosphere lighter than air <
A different type of balloon would be required for the atmosphere
of Jupiter, the biggest planet in the solar system. Its atmosphere
is rich in hydrogen gas, the lightest of gases; hence an Earth-like
hydrogen-gas balloon would not be buoyant enough to float.
A Jovian balloon would be a special kind of "hot-air" balloon. It
would be kept aloft partly by heat absorbed from sunlight. It could
also be kept floating by the large amounts of "internal" heat
Jupiter emits as it slowly contracts under the pull of its enormous
gravity, Cutts says.
This summer, JPL engineer Jack Jones is testing hot-air-type
balloons for Mars missions at a blimp hangar in Tillamook, Ore.
One of the strangest proposed robots is a worm-like device. It
would drill into the Martian crust, like a super-worm.
"We are building a (worm-like) device a few inches in diameter
and 3 to 6 feet long, and 1 1/4 inches in diameter," says Wilcox,
47. Ideally, it could drill at least a mile into the Martian crust
to look for buried microbes in ground water.
The robot would be connected to the surface by long wires and
capillary tubes. The former would transmit electric power from solar
panels on the surface.
The tubes - filled with liquefied carbon dioxide condensed from
the Martian atmosphere - would pump subsurface grains (perhaps even
microbes) back to the surface.
The "worm" would drill through the crust by repeatedly firing a
tungsten "hammer" into the rock. Its technical name is "robotic
subsurface explorer" or SSX.
But "I prefer to describe it as a self-hammering nail," Wilcox