Scientists consider the feasibility of transferring energy through the atmosphere of Venus

A few weeks ago, a team of scientists from Caltech announced that they had successfully transmitted energy from a satellite orbiting the Earth. That’s not a lot of energy, but it shows that it’s possible.

Finally, we can channel energy from solar satellites down to Earth, making solar energy available almost everywhere and helping to combat climate change. But there’s another potential use: powering surface probes on Venus.

Everyone knows about Venus. It killed many landers with extreme heat and crushing atmospheric pressure. The former Soviet Union sent a series of probes to the surface of the planet and most of them failed. The most successful was the Venera 13, which lasted just over two hours at 457 °C (855 °F) and was subjected to a pressure of 9.0 MPa (the standard 89 atmospheres).

Despite the brief but critical success of Venera 13, the planet holds its secrets, and we are drawn back to its surface to reveal them. That’s why NASA wants to send a lander to the surface as part of the DAVINCI+ (Venus Deep Atmospheric Investigation of Noble Gases, Chemistry, and Imaging) mission.

But the question arises as to how to power a dangerous, unique surface lander on Venus, assuming we can build one that won’t succumb so easily. Venus’s unpleasant conditions. Conventional methods—solar, battery, radioisotope thermoelectric generators—failed to meet the task. That’s according to new research titled, «The Feasibility of Energy Transmitted Through the Atmosphere of Venus,» published in the journal Acta space travel. The corresponding author is Erik Brandon from the Jet Propulsion Laboratory.

The authors explain: “Advanced space-energy technologies including solar arrays, batteries and radioisotope thermoelectric generators are not capable of operating on the surface of Venus, and are limited. by high temperature, high pressure and corrosive environment”.

Venus is closer to the sun, but its dense atmosphere means not much solar radiation reaches the surface. About 75% of the sun’s energy is reflected by the clouds of Venus, and only about 2.5% of the solar flux at the top of the atmosphere reaches the surface. Above the clouds, solar energy is abundant. Venus receives twice as much solar radiation at the top of the atmosphere as Earth does at the top of the atmosphere.

Could this abundant energy be harnessed by solar collectors above the clouds and then beamed down to the lander/robot? It will have to pass a lot of thick clouds. «The feasibility of such an approach and other related mission concepts are discussed here from the perspective of atmospheric absorption and beam energy scattering,» the paper reads.

Transferring energy from one place to another is called wireless energy (or energy) transfer. There are two types: near field and far field. Near field is the transfer of energy over short distances like the kind used in charging pads for mobile devices. Far-field energy transfer is also known as power transfer and it uses microwaves or lasers to transfer energy from the manufacturer to the receiver.

One problem with energy transfer from an orbiting solar collector to a surface vehicle is the complexity in Venus’s geostationary orbit. The planet rotates so slowly that the geostationary orbit is at a great distance from the planet, making the orbit unstable. Somehow, a solar collector would need to be closer to the planet. Above the upper clouds, at an altitude of about 60 or 70 km, a collector will essentially receive all available sunlight. Task design may have to keep collectors or groups of collectors at the right height and location.

An alternative would be to transfer some of the power to the lander on each orbiter, which may be sufficient. The authors explain: “Hundreds of Wh (Watt-hours) of energy can be obtained during the lander’s passage through several orbits.

But those are the bigger problems of the overall task architecture. This study assumes that there are solutions to that problem. In this work, the authors focus on how energy is transmitted and received, something that has not been well studied. “However, to date, there has not been a thorough study of the feasibility of energy transfer at the right wavelengths, if a suitable platform and mission structure can be devised and implementation,” the authors write.

The problem is that Venus’s atmosphere is dense and contains chemicals that interfere with microwave energy transfer. CO . gas₂ concentration is a specific issue.

Laser may be a better option. Despite the problems with dense atmospheres, there are still certain «frequency windows» in the atmosphere that can allow laser emission. The authors write: “Conversely, beam emission through laser sources on Venus can be achievable despite continuous cloud cover, due to some optical/infrared ‘windows’ present in the atmosphere. atmosphere of Venus, which is not available using microwave energy rays.

Lasers also have other advantages, such as reduced beam propagation compared to microwaves. That means the receiving antenna doesn’t need to be too big. A one meter receiver might be enough and wouldn’t be too unwieldy to interfere too much with the design of a lander.

Although solar energy is abundant at the top of Venus’s atmosphere, shining it down on the entire atmosphere may not be the best approach. Instead, a balloon or some other vehicle could place itself near the middle of the atmosphere. There, it would receive enough solar energy for viable operation and only need to beam the energy through part of the atmosphere.

Research shows that the 47 km altitude is significant. There is a cloud base at that altitude and below it the beam energy is less scattered. It also shows that from 47 km, the highest transmission coefficient is 1022 nanometers, where about 20% of the beam energy will reach the surface lander.

«These calculations indicate a plausible approach to transmitting energy to Venus, using a transmission from an airborne platform operating near the cloud base,» the authors write.

But does the technology to do this exist? The article does not discuss what types of vehicles or platforms can be used at an altitude of 47km. They focus on the emitted energy itself, and if calculations show it is possible. But they also talk about existing laser technology and whether it’s up to the task.

According to the researchers, we don’t have the right laser yet.

However, researchers are busy developing them. Ytterbium-doped fiber lasers (YDFLs) operating in the near-infrared (NIR) window that can also operate at high power are under development. Unfortunately, they do not operate at the ideal wavelength for use at Venus: 1022. Instead, they are limited to two other bands: 970–980 nm and 1030–1100 nm. However, lasers are the focus of various researchers around the world and progress remains steady.

The task of keeping some sort of aerial platform stable and in place is crucial to any power-up mission. But researchers have been working on hot air balloons and other airborne platforms for use on Venus. Assuming they can be developed, the authors are confident that a scenario that shines with power can rise to the challenge and generate successful missions to the surface of Venus.

«In addition, despite the engineering and mission design challenges involved in controlling and orienting such an air vehicle platform used for energy transfer and overall thermal management, the This analysis shows that these optical windows can be exploited to provide sufficient energy levels to enable the mission to be projected to the surface of Venus.»

We need to better understand Venus’s atmosphere before we can design a specific system. DAVINCI+ has three main scientific goals, and one of them is to understand the atmosphere as it moves through it.

Its findings will help scientists understand the obstacles they face in transmitting energy to the planet’s surface. If it can be reliably done, then Venus will be ready for exploration.