Interstellar travel, closer through the development of antimatter engines

Interstellar travel is something humanity has only achieved in science fiction – such as Star Trek's USS Enterprise, which used antimatter engines to travel through star systems.

Travel in the Cosmos PHOTO: Archive

Antimatter isn't just a sci-fi trope. Antimatter really exists.

Elon Musk called antimatter energy “the ticket for interstellar travel,” and physicists like Ryan Weed are exploring how to exploit it, writes

Antimatter is made up of particles almost the same as regular matter, but with the opposite electrical charge. This means that when antimatter comes into contact with ordinary matter, both annihilate each other and can produce enormous amounts of energy.

“The annihilation of antimatter and matter converts mass directly into energy,” Weed, co-founder and CEO of Positron Dynamics, a company working to develop an antimatter propulsion system, told Business Insider.

Just one gram of antimatter could generate an explosion equivalent to a nuclear bomb. It is this kind of energy, some say, that could boldly take us where no one has gone before, at record speed.

Space travel at record speed

The advantage of this energy is that it can be used to accelerate or decelerate spacecraft to dizzying speeds.

For example, let's take a trip to the nearest star system, Proxima, which is about 4.2 light years away.

An antimatter engine could theoretically accelerate a spacecraft by 1g (9.8 meters per second squared), which could get us to Proxima in just five years, Weed said in 2016. That's 8,000 times faster than it would take Voyager 1 — one of the fastest spacecraft in history — to travel about half the distance, according to NASA.

Even within our own solar system, an antimatter-powered spacecraft could reach Pluto in 3.5 weeks, compared to the 9.5 years it took NASA's New Horizons probe to reach, he said Weed.

Why don't we have antimatter engines

The reason we don't have antimatter engines, despite their extraordinary capabilities, comes down to cost, not technology.

Gerald Jackson, an accelerator physicist who worked on antimatter projects at Fermilab, told Forbes in 2016 that with enough funding, we could have a prototype antimatter spacecraft within a decade.

The basic technology exists. Physicists armed with the world's most powerful particle accelerators have made antiprotons and antihydrogen atoms.

The problem is that this type of antimatter is incredibly expensive to manufacture. It is considered the most expensive substance on Earth. Jackson gave us an idea of ​​how much an antimatter machine would cost to build and maintain.

Jackson is the founder, president and CEO of Hbar Technologies, which is working on an antimatter space sail concept to decelerate spacecraft traveling at 1% to 10% of the speed of light — a concept useful for entering orbit around of a distant star, planet, or moon you want to study.

Jackson said he had designed an asymmetric proton accelerator that could produce 20 grams of antimatter per year.

“For a 10-kilogram science package traveling at 2% of the speed of light, 35 grams of antimatter is required to decelerate the spacecraft and inject it into orbit around Proxima Centauri,” Jackson told BI.

He stated that it would take $8 billion to build a solar plant for the enormous energy needs of antimatter production and would cost $670 million a year to operate.

The idea is just that, for now. “There is currently no serious funding for advanced space propulsion concepts,” Jackson said.

However, there are other ways to produce antimatter. This is where Weed focused his work.

Weed's concept involves positrons, the antimatter version of an electron.

Another type of antimatter engine

Positrons “they are several thousand times lighter than antiprotons and not as powerful when they annihilate”Weed said.

However, their advantage is that they occur naturally and do not require a giant accelerator and billions of dollars to produce.

Weed's antimatter propulsion system is designed to use krypton-79 – a form of the element krypton that naturally emits positrons.

The engine system would first collect high-energy positrons from krypton-79 and then direct them into a layer of ordinary matter, producing annihilation energy. This energy would then trigger a powerful fusion reaction to generate the thrust for the spacecraft.

Although positrons may be less expensive to obtain than stronger forms of antimatter, they are difficult to exploit because they are very energetic and must be slowed down or “moderate”. So building a prototype to be tested in space is still out of reach from a cost perspective, Weed said.

This is the case for all antimatter propulsion models. Over the decades, scientists have proposed dozens of concepts, none of which have come to fruition.

For example, in 1953, the Austrian physicist Eugen Sänger proposed a “photon rocket” that would work with the annihilation energy of positrons. And since the 1980s, there has been talk of antimatter heat engines, which would use antimatter to heat liquid, gas, or plasma to provide thrust.

“It's not sci-fi, but we won't see it fly until there's a significant 'mission-pull',” Weed said of his engine concept.

Can it work?

To build Weed's concept to the scale of a spaceship, “the devil is in the technical details”astrophysicist and podcast host Paul M. Sutter told BI “Ask a Spaceman”.

We're talking about a device that harnesses truly enormous amounts of energy, requiring exquisite balance and control.” Sutter said.

Overall, this enormous energy is another obstacle preventing us from revolutionizing space travel. Because during the tests, “if something goes wrong, these are big explosions,” a Steve Howe, a physicist who worked on antimatter concepts with NASA in the 1990s, told BI.

“So we need an ability to test high energy density systems somewhere that doesn't threaten the biosphere but still allows us to develop them.” said Howe, who thinks the Moon would be a good test bed. “And if something goes wrong, a piece of the Moon melts”and not by Earth, he added.

Antimatter tends to unleash the imagination of all who work on it. “But, we need crazy but plausible ideas to get further into space, so it's worth looking at them”Sutter said.

Weed echoes this sentiment, saying that “until there is a compelling reason to get to the Kuiper Belt, the solar gravitational lens, or Alpha Centauri very quickly – or maybe we're trying to turn large asteroids for mining – progress will continue to be slow in this area.”