Mars gets a lot of attention from earthlings these days, but recently Venus is coming under the spotlight, with NASA, its European counterpart ESA, and New Zealand spaceflight company Rocket Lab all planning to send missions there in the coming years.
Besides these, NASA is also considering exploring the inhospitable planet by sailing a robotic “aerobot” balloon in the Venusian winds.
As part of research for the potential mission, NASA’s Jet Propulsion Laboratory (JPL) recently completed two test flights of an aerobot prototype over Nevada’s Black Rock desert, successfully demonstrating controlled altitude flights in the process.
Sending a spacecraft to Venus is a tricky proposition as its extremely high pressure, intense heat, and corrosive gases would render it useless in just a few hours. But a few dozen miles above the inhospitable zone is an area in which an aerobot would be able to maneuver safely.
“One concept envisions pairing a balloon with a Venus orbiter, the two working in tandem to study Earth’s sister planet,” JPL explains on its website. “While the orbiter would remain far above the atmosphere, taking science measurements and serving as a communication relay, an aerial robotic balloon, or aerobot, about 40 feet (12 meters) in diameter, would travel into it.”
The prototype balloon features a rigid, helium-filled inner reservoir and an outer helium balloon that’s able to expand and contract. Helium vents allow the gas to pass between the inner and outer section, altering buoyancy levels and thereby giving scientists a way to control the altitude of the aerobot.
To test the design, scientists and engineers from JPL and the Near Space Corporation — a commercial provider of high altitude, near-space platforms — conducted two flights to test a prototype balloon about a third of the size of the one that would go to Venus.
The balloon flew 4,000 feet (1 kilometer) to a place in Earth’s atmosphere that’s similar to the density that the aerobot would experience about 180,000 feet (55 kilometers) above Venus, JPL said.
The success of the Nevada tests suggests the aerobot could float high above Venus for weeks or even months, ample time for monitoring the atmosphere for acoustic waves generated by venusquakes and analyzing the chemical composition of the planet’s clouds, among other missions goals, with all of the gathered data beamed back to Earth via the accompanying orbiter.
“We’re extremely happy with the performance of the prototype,” said JPL robotics technologist Jacob Izraelevitz. “It was launched, demonstrated controlled-altitude maneuvers, and was recovered in good condition after both flights.”
Izraelevitz added: “We’ve recorded a mountain of data from these flights and are looking forward to using it to improve our simulation models before exploring our sister planet.”
Balloons have been seen as a viable method for Venus exploration ever since the Soviets successfully used such a design as part of the twin Soviet Vega 1 and 2 missions in 1985. The two helium-filled balloons sailed on the Venusian winds for just over 46 hours before their instruments’ batteries ran out. “Their short time in the Venusian atmosphere provided a tantalizing hint of the science that could be achieved by a larger, longer-duration balloon platform floating within the planet’s atmosphere,” JPL said.
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