NASA marks major milestone is testing balloon-borne technology to explore Venus

NASA's Jet Propulsion Laboratory (JPL), on October 11, announced a major milestone as it successfully completed test flights of the Aerial Robotic Balloon prototype that could one day help in the exploration of Venus. The agency is planning to eventually scale down its size and attach an orbiter for taking measurements of the Venusian atmosphere from a specified altitude.

The idea of deploying a balloon-borne spacecraft is being preferred because the intense pressure, heat and corrosive gases on Venus's surface can destroy even the most robust spacecraft whereas the atmosphere a few kilometres above is considered more forgiving.

How would the idea work?

The technology being developed by NASA's JPL involves an orbiter attached to a balloon about 40 feet (12 metres) in diameter that will travel through the Venusian clouds from east to west and circumnavigate the planet for at least 100 days. During the mission, the orbiter would conduct investigations such as monitoring the atmosphere for acoustic waves generated by Venusquakes and analyzing the chemical composition of the clouds.

In the recent tests at the Black Rock Desert in Nevada, US, scientists from JPL and Near Space Corporation flew the balloon to an altitude of over one kilometre (4,000 feet). NASA says that this region of the Earth's atmosphere approximates the temperature and density the aerobot will experience about 55 kilometres (1,80,000 feet) above the Venusian surface. The experts concluded that the two flight tests proved the concept's suitability that a region of Venus'atmosphere that is otherwise too low for orbiters can be accessed using balloons for months at a time.

"We’re extremely happy with the performance of the prototype. It was launched, demonstrated controlled-altitude maneuvers, and was recovered in good condition after both flights,” said robotics technologist and JPL principal investigator Jacob Izraelevitz in a statement. "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.”

A sufficient amount of exploration time is important because the previous balloon missions sent to Venus (Vega 1 and Vega 2) were by the Soviet Union in December 1984 and they lasted just a little over 46 hours. Measuring 11.5 feet (3.6 metres) in diametre, it was the Vega twins that provided tantalising potential of science that can be conducted on Venus using long-duration missions.

According to NASA, its balloons designed by Near Space have a rigid inner reservoir filled with helium under high pressure and an encapsulating outer helium balloon that can expand and contract. This would allow the mission controllers to raise and lower the orbiter's altitude by pumping the helium gas in and out of the balloon's reservoir. To protect the balloon from Venus'sulfuric acid clouds, they have been provided an acid-proof coating along with a metallisation layer to reduce solar heating, and an inner structural layer to make it strong enough to carry the science instruments below. 

"The materials being used for Venus survivability are challenging to fabricate with, and the robustness of handling we’ve demonstrated in the Nevada launch and recovery gives us confidence for balloon’s reliability on Venus,” said co-investigator and Near Space CEO, Tim Lachenmeier.