In 1835, an article appeared in the Southern high-res photos and possibly even scooping up
Literary Messenger telling the remarkable story of surface samples for onboard analysis.
one Hans Pfaall, a bellows-mender from Rotterdam “Balloons provide a unique observation platform
who escaped his creditors by flying a homemade for doing planetary science that you simply can’t do
hot air balloon to the moon. The story turned out to any other way,” says Jeffery Hall, the senior engi-
be a prototypical bit of science fiction dreamt up by neer who leads JPL’s aerobot research.
a young Edgar Allen Poe to dupe his readers. The An aeronautical engineer by training, Hall joined
idea of ballooning to the moon or elsewhere in the JPL in 1997 after graduating from Cal Tech down the
solar system never took off, probably because it’s road. At the time, he worked on cryogenic technolo-
impossible. But for a certain group of engineers, gies for satellites. Then, he says, the funding dried
flying balloons on other planets isn’t far-fetched at up and he was forced to expand his horizons.
all. In fact, the Russians have already done it. And “I’ve always been motivated to figure out how
NASA’s Jet Propulsion Laboratory (JPL) is keeping things work, and that inevitably leads you to build-
the tradition alive. ing stuff for experiments,” he says. “One of the great
A sprawling campus just north of Los Angeles, attractions of balloons is that it’s fairly easy to
NASA’s Jet Propulsion Laboratory was established make them. Then you get to take them outside and
by the California Institute of Technology in the fly them around. From an experimentalist’s point of
1930s. Emerging from the DIY mindset that view, they’re fun things to work with.”
launched the science of rocketry in this country, The Titan balloon is just one of several very differ-
JPL was where the first U.S. satellite was designed, ent aerial vehicles that Hall and his colleagues are
the Mariner and Voyager probes were born, and the designing. Each vehicle’s technology is dictated by
long-running Mars rovers were built. its ultimate destination. For example, the very thin
In a small cluster of bunkers at the heart of the atmosphere of Mars requires a spherical balloon at
campus lies JPL’s Mobility and Robotic Systems lab- least ten meters in diameter to carry just a couple
oratory. About 100 engineers develop all of the robot- kilograms of scientific instruments.
ic components, from the autonomy software to the In one scheme, the balloon package would be
mechanical appendages that enable us to explore released from a spacecraft upon entry into the
other worlds while staying safely on terra firma. Mars atmosphere. As the canopy drifts down
In a back room of the laboratory, a white blimp, beneath a parachute, onboard helium tanks inflate about 15 feet long, floats above a table, secured by the “envelope,” the actual balloon fabric. Once the tethers. The blimp doesn’t seem particularly envelope is filled, the parachute and tanks are cut unique, that is until you hear that it’s a prototype loose and the balloon settles at an altitude a few for an autonomous nuclear-powered aerobot that miles above the surface. According to Hall, a wind-could someday explore Saturn’s moon Titan. The blown helium superpressure balloon like this could blimp would fly below the dense clouds that hide float around the planet for up to a year, all the while the terrain from orbiting spacecraft, snapping transmitting data back to mission control on Earth.
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