The Venus balloon aerobot makes its first test flights

Scientists and engineers tested the Venus balloon prototype in the Black Rock Desert, Nevada in July 2022. The scaled-down aerobot has successfully completed 2 initial test flights. Picture via Nasa/ JPL-Caltech.

A Venus balloon?

With its scorching heat and crushing pressure, the surface of Venus is hostile and unforgiving. In fact, the probes that have landed there so far have only lasted a few hours at most. But, with orbiters, there could be another way to explore this dangerous but fascinating world, which orbits the sun one step away from Earth. And it is with balloons. NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, reported on October 10, 2022, that one of its concepts for a aerobot – an aerial robotic balloon – has successfully completed two test flights over Nevada.

The researchers used a test prototype, a scaled-down version of a balloon that could one day drift among the dense clouds of Venus.

Test flights of the 1st Venus balloon prototype

The planned Venus aerobot would be 40 feet (12 meters) in diameter, about 2/3 larger than the prototype.

A team of scientists and engineers from JPL and the Near Space Corporation in Tillamook, Oregon, performed the test flights. Their success shows that a Venus balloon should be able to survive in the dense atmosphere of this neighboring world. On Venus, the balloon would fly at a height of 180,000 feet (55 kilometers) above the surface. To match the temperatures and densities of the Venusian atmosphere during testing, the team raised the test balloon to a height of 4,000 feet (1 kilometer).

By all accounts, the balloon performed exactly as it was designed. robotics technologist Jacob Izraelevitzthe principal flight test investigator for JPL, said:

We are extremely satisfied with the performance of the prototype. It launched, demonstrated maneuvers at controlled altitude and we recovered it in good condition after the two flights. We have recorded a mountain of data from these flights and look forward to using it to improve our simulation models before exploring our sister planet.

Paul Byrne at Washington University in St. Louis and a collaborating aerobot scientist added:

The success of these test flights is very important to us: we have successfully demonstrated the technology we will need to study the clouds of Venus. These tests form the basis of how we can achieve long-term robotic exploration above the hellish surface of Venus.

Traveling on the Venusian winds

So why a ball? NASA wants to study the region of Venus’ atmosphere that is too low in altitude to be analyzed by orbiters. And unlike landers that burn out in hours, a balloon can float in the wind for weeks or even months, drifting east to west. The balloon could also vary its altitude between 171,000 and 203,000 feet (52 and 62 kilometers) above the surface.

The aerobot is not, however, entirely alone. It works with an orbiter above the atmosphere of Venus. In addition to conducting its scientific experiments, the balloon serves as a communication relay with the orbiter.

A “ball within a ball”

The researchers said the prototype was essentially a “balloon within a balloon”. Pressurized helium fills the rigid inner tank. The flexible outer helium balloon, meanwhile, can expand and contract. The balloon can also rise higher or fall lower in altitude. It does this using helium vents. If the mission team wants the balloon to rise, they vent helium from the inner tank to the outer balloon. To bring the balloon back down, helium is returned to the tank. This causes the outer balloon to shrink and lose some of its buoyancy.

A corrosive environment

At a predicted height of 180,000 feet (55 km) above the surface of Venus, air temperatures aren’t so hellish and atmospheric pressures are less intense. But this part of Venus’ atmosphere can still be quite harsh as the clouds are filled with droplets of sulfuric acid.

To help protect against this corrosive environment, engineers constructed the balloon from a multi-layered material. This material has an acid-resistant coating, a metallization layer to reduce solar heating, and an inner layer that keeps it strong enough to transport scientific instruments. Even the seals are acid resistant. Flight tests show that the balloon material and construction should also work on Venus. As a co-researcher Tim LachenmeierCEO of Near Space Corporation, Explain:

The materials used for Venus survivability are difficult to manufacture, and the robust handling we demonstrated during launch and recovery in Nevada gives us confidence in the reliability of the balloon on Venus.

Five airship type balloons hovering above the white cloud deck with the sun above.
Some scientists and engineers have proposed balloons as a way to explore Venus for decades. This could soon become a reality. Picture via Nasa.

Science in the atmosphere of Venus

Scientists have equipped the balloon to conduct a variety of scientific investigations. These include searching for acoustic waves in the atmosphere generated by earthquakes (the Venusian version of earthquakes). One of the most fascinating analyzes to be made would be that of the composition of the atmosphere itself. Carbon dioxide makes up most of Venus’ atmosphere, fueling the runaway greenhouse effect that turned the planet into such a hell on the surface. Further analysis could provide important clues as to exactly how this happened. Indeed, at first, Venus was more like Earth, scientists say. So what happened?

And, of course, since scientists have reported discovery of phosphine in the planet’s atmosphere in 2020, the question of possible life in the clouds of Venus is experiencing renewed interest. The jury is still out on where phosphine came from – and some studies still question its existence – but balloon missions like this would be ideal for doing in-depth cloud analysis and maybe even directly identify any microscopic organism.

There is much to discover on our nearest neighboring planet. Balloon missions like this could help uncover some of its most confusing and difficult secrets.

Conclusion: Engineers and scientists at NASA’s Jet Propulsion Laboratory have successfully completed two test flights of a Venus robotic balloon prototype. The balloon, known as the Aerobot, could one day explore Venus’ atmosphere.

Through JPL