Writing in the latest edition of the journal Acta Astronautica (vol 56, p 750), a team led by Geoffrey Landis of NASA's Glenn Research Center in Ohio says that an autonomous solar-powered aircraft could cruise between different altitudes and locations in Venus's wild atmosphere, making measurements and radar-imaging the surface at 10 times the resolution possible with an orbiting craft. They say this would provide far better data than the Soviet and US probes of the 1970s and 1980s, which were only able to make atmospheric measurements for a short time as they descended to their doom in the planet's violent, corrosive winds. But the planet's dense atmosphere is ideal for a flying craft. A wing's lift depends directly on the density of the atmosphere and the atmospheric pressure on Venus is about 90 times that of Earth. After being released by an orbiter, the craft's origami-like wings would unfurl from an "aeroshell" . Solar panels on the craft's surface could absorb large amounts of the intense solar energy, powering motors to allow the craft to fly continuously. And the planet's slow rotation, with one day and night on Venus taking 117 Earth days, means a solar flyer could stay on the daylight side indefinitely.
But down on the ground, where temperatures on the planet's day-side reach around 450 °C, a rover undertaking geological and imaging work would not last long. "We think we can get electrical things like motors and transistors to work at those temperatures, but not the microelectronics for computers," says Landis, who is also part of the science team running the Spirit and Opportunity missions. His answer is to land a relatively dumb rover on the surface - which would be heat-proof, acid-proof and pressure-proof. The microchips that control the rover's motion, communication and imaging would be housed on the solar-powered flyer 50 kilometres above. "With no vulnerable on-board computer, we might then be able to duplicate the Spirit and Opportunity missions," Landis says. The down side would be the delay while the flying computer relays data to or from the dumb rover via a radio link.