French startup sails (solar) into space

When you think of a space rocket, you see a mountain of technology. But few people understand how full a launcher actually is. Because it is nevertheless the biggest problem in the world of space today. Whether it is electrical or chemical (with an impulse), the latter is finite, and it weighs heavily on the scales. But to go into space, every (kilogram) counts. So it is necessary to lighten other elements, such as the payload, or push more to release more weight toward orbit.

To respond to this fuel problem, the best is to simply remove it. With this idea, as crazy and simple as it is, Louis de Gouyon launched Matignon Gama in October 2020 together with Thibaud Elziere. Since then, this company, based in the Paris region, has been working hard to produce a “spacecraft” without fuel, and therefore without an engine.

You can find the full interview with Louis de Gouyon Matignon on Presse-citron.

Centuries-old principle

Behind this engineering feat, in fact, hides a method more than 300 years old, which was known to astronomers even before the Sputnik flight. As sailors have done for a very long time, the goal of Gamma is to make a probe that flies and travels thanks to a sail. An idea to say the least surprising, but it does not slow down the development of the young company. Today, the company announced a two million euro fundraising, among others, with BPI France and CNES, demonstrating the seriousness of the project.

Imagined by the famous astronomer Johannes Kepler centuries ago, and then confirmed by Maxwell’s work, a solar sail has never won engineers, and hardly anyone has ever sent a single person into space, despite our very good theoretical knowledge about it. As Louis Gouyon de Matigon explains. “Today there should be 10,000 satellites in space, and those with a solar sail must be counted with the fingers of one hand.” So the Gamma project is very ambitious, not to mention unprecedented. In fact, only the IKAROS probe, which was launched by the Japanese Space Agency (JAXA) at the beginning of the last decade, showed convincing results.

The first learning journey of 2022

Finally, the theory behind how a solar sail works is quite simple. As with sailboats at sea, the idea is to be propelled by weathering. But it is clear that in space, there is not the slightest gust of wind – the solar wind has no effect on the thrust here – and therefore the sail will reflect the light coming from the Sun, and it is precisely the photons that make up the latter, that will push the sail (which explains the name photon thrust) .

For Gamma we have the right to a sail of approximately 75 square metres, built on four pedals of approximately 20 square metres. This square veil is extremely thin – 20 to 100 times thinner than a hair – and so photons will push it into the vacuum of space. “The great advantage of this system is that the thrust is theoretically infinite. Although small, it accumulates and over time we reach incredible speeds » Louis de Guyon Matignon explains.

In order to perform the first life-size test, Gamma is preparing to launch into orbit, thus propelling the sail and the hopes of the entire community into space. The flight is scheduled to take place next October on a Falun 9 plane from the American company SpaceX. This mission should make it possible to verify that “everything is fine” and ensure a first experience with the space vacuum of the fledgling company and its 10 engineers, all from Ile-de-France.

Venus lens?

But for the young French company, the goal will be to take off very quickly in deep space interstellar space. As such, the company hopes to be able to carry out a mission around 2025.” To Venus or an asteroid. A major step in the development of gamma, which will allow us to achieve our first exploration goal. “Recreating a picture of Venus would be really incredible.” Explains Louis de Guyon Matignon, who struggles to hide his enthusiasm.

Made of tactile polyamides, this sail is just three microns thick for 11 kilograms on the scale. “Folded, it’s the size of a shoebox”, Once in space, it unfolds thanks to the centrifugal force of the probe itself. “Thanks to the small blocks, the sail will open in the opposite direction to the probe’s rotation.” Once deployed, the probe will reflect sunlight and be propelled by it.

On Earth, we know only one of the two forces of the Sun. Thermal effect of its rays. But our star is also capable of moving objects with the power of its photons. These particles (which are also waves) release neither mass, nor energy, nor heat, but when they come into contact with matter, they push it very slightly. This is the thrust that a gamma sail uses to navigate through space.

Infinite power… on paper

If the thrust generated by the photons is absurd compared to a conventional rocket engine, a sail is an (or nearly) inexhaustible source of energy. As Louis de Gouyon Matignon explains, photonic propulsion is ideal for low-cost remote exploration.

“By removing fuel from the probes, we provide a system that is much lighter, and therefore costs less to send into space, and can, in addition, last longer over time.” Although the veil system is not eternal, radiation from space and micrometeorites will eventually improve. Ultra-thin life blanket It is possible to accelerate the probe, as the sun’s rays collide with the sun’s rays.

With a minimal continuous supply of power, it is then possible to imagine additional exploration. So Gamma plans to go to Jupiter or Neptune in a few years. Thanks to the power of the Sun, the probe, which weighs a few kilograms, will be able to move at insane speeds “Which cannot be accessed today by chemical propulsion.” By playing with the celestial mechanics and the different gravitational forces of our solar system, it will be possible to travel to Neptune or the moons of Jupiter.

Missions that can be performed using chemical propulsion sensors, which have already been carried out in the past, but only government space agencies have been able to afford such a flight. With the gamma system, the solar sail can reduce the cost of the mission, but also the duration of the latter.

The solar sail has an Achilles heel: the orbit

If photon propulsion has many advantages, this system is not ideal. It is these shortcomings that have made the solar sail so unpopular in the world of low orbit, which is today the main stadium of the new space. The first thing to remember about a solar sail is that the latter, by its very design, is not able to have a very high reaction.

This is not a problem for distant exploration missions, but for satellites or probes in orbit, reaction speed is essential. “If you have a satellite in low orbit, you want to tilt it to see another area of ​​Earth, you push a button in your command center and you’re done. We, with a solar sail, can’t do that” He gets acquainted with Louis de Gouyon Matignon.

But this lack of interactivity isn’t the solar sail’s only drawback. In fact, the latter also produces a “footprint” when it moves in orbit around the Earth. Hundreds of kilometers above our heads, there are always a few atoms of air, and these will return the sail to the earth. Due to its large size, the sail will descend more quickly than conventional satellites, which also have a propulsion system to compensate for this return to the blue planet.

Gamma: the lens of the solar system

In short, photonic thrust is not made for Earth, and everyone is well aware of that at gamma. In fact, if the company aims to launch orbit for the first time in October, it does not intend to stay there and hopes to be able to reach the four corners of the solar system as quickly as possible.

In any case, with this revolutionary propulsion system, Gama does not lack ambition, and hopes to be able to produce many more sails in the coming years, in order to double the launches and thus achieve a certain financial balance.