Lasers can send missions to Mars in just 45 days

A swarm of spaceships with laser sails leaves the solar system. Credit: Adrian Mann

Mars in the next decade. While this represents a tremendous leap in terms of space exploration, it also presents significant logistical and technological challenges. For starters, missions can only launch for Mars every 26 months when our two planets are at the closest points in their orbit to each other (during an “Opposition“). Using current technology, it would take six to nine months to transit from Earth to Mars.

Even with nuclear-thermal or nuclear-electric propulsion (NTP/NEP), a one-way transit could take 100 days to reach Mars. However, a team of researchers from Montreal’s McGill University assessed the potential of a laser-thermal propulsion system. According to their study, a spacecraft that relies on a novel propulsion system – where lasers are used to heat hydrogen fuel – could reduce transit times to Mars to just 45 days!

The research was led by Emmanuel Duplay, a McGill graduate and current MSc Aerospace Engineering student at TU Delft. He was joined by Associate Professor Andrew Higgins and multiple researchers with the Department of Mechanical Engineering at McGill University. Their study, titled “Design of a rapid transit to Mars mission using laser-thermal propulsion,” was recently submitted to the journal Astronomy & Astronomy.

Directed Energy Propulsion Laser Sail

Artist’s impression of a directed-energy propulsion laser sail in action. Credit: Q. Zhang/

In recent years, directed-energy (DE) propulsion has been the subject of considerable research and interest. Examples include the Starlight program – also known as the Directed Energy Propulsion for Interstellar Exploration (DEEP-IN) and Directed Energy Interstellar Studies (DEIS) programs – developed by Prof. Phillip Lubin and the UCSB Experimental Cosmology Group (ECG). As part of NASA-funded research that began in 2009, these programs aim to adapt large-scale DE applications for interstellar missions.

There’s also Breakthrough Starshot and Project Dragonfly, both of which emerged from a design study hosted by the Initiative for Interstellar Studies (i4iS) in 2013. These concepts call for a gigawatt-power laser array to accelerate a lightsail and a small spacecraft to a fraction of the speed of light (aka. relativistic speeds) to reach nearby star systems in decades, rather than centuries or millennia.

But whereas these concepts are interstellar in focus, Duplay and his colleagues explored the possibility of an interplanetary concept. As Duplay explained to Universe Today via email:

“The ultimate application of directed-energy propulsion would be to propel a lightsail to the stars for true interstellar travel, a possibility that motivated our team that did this study. We were interested in how the same laser technology could be used for rapid transit in the solar system, which will hopefully be a nearer-term steppingstone that can demonstrate the technology.”

Project Starshot

Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit:

Aside from laser sail propulsion, DE is being explored for several other space exploration applications. This includes power beaming to and from spacecraft and permanently-shadowed habitats (e.g., the Artemis Program), communications, asteroid defense, and the search for possible technosignatures. There’s also a concept for a laser-electric spacecraft being investigated by NASA and as part of a collaborative study between the UCSB ECG and MIT.

For this application, lasers are used to deliver power to photovoltaic arrays on a spacecraft, which is converted to electricity to power a Hall-Effect Thruster (ion engine). This idea is similar to a nuclear-electric propulsion (NEP) system, where a laser array takes the place of a nuclear reactor. As Duplay explained, their concept is related but different:

“Our approach is complimentary to these concepts, in that it uses the same phased-array laser concept, but would use a much more intense laser flux on the spacecraft to directly heat propellant, similar to a giant steam kettle. This permits the spacecraft to accelerate rapidly while it is still near earth, so the laser does not need to focus as far into space.

“Our spacecraft is like a dragster that accelerates very quickly while still near earth. We believe we can even use the same laser-powered rocket engine to bring the booster back into earth orbit, after it has thrown the main vehicle to Mars, enabling it to be quickly recycled for the next launch.”

Nuclear Rocket Mars Mission

An artist’s concept for a nuclear rocket that would facilitate missions to Mars. Credit: Rolls-Royce

In this respect, the concept proposed by Duplay and his colleagues is akin to a nuclear-thermal propulsion (NTP) system, where the laser has taken the place of a nuclear reactor. In addition to DE and hydrogen propellant, the mission architecture for a laser-thermal spacecraft includes several technologies from other architectures. As Duplay indicated, they include:

“[A]fiber-optic laser beams acting as a single optical element, inflatable space structures that can be used to focus the laser beam when it enters the spacecraft into the heating chamber, and the development of high-temperature materials that allow the spacecraft to sail against the spacecraft. ».

This last element is very important, given that there is no laser platform on Mars that would slow down a spacecraft as soon as it reaches Mars. “The inflatable reflector is the key to other directional energy architectures: designed to have a high reflectivity, it can withstand more laser power per unit area than a photovoltaic panel, making this mission feasible with a small laser array size compared to a laser array. electric. movement, ”Dupleix added.

Combining these elements, the laser-thermal rocket could provide very fast transits to Mars, which would take six weeks – something that was previously considered possible only with nuclear rocket engines. The most immediate benefit is that it is a solution to the dangers of transit into deep space, such as prolonged exposure to radiation and microgravity.

Mars base camp in orbit

Impression of the artist from the base camp of Mars in orbit around Mars. If missions to Mars begin, one of the biggest risks will be space radiation. Credit: Lockheed Martin

At the same time, Duplay says, the mission poses some obstacles because many of the technologies involved are advanced and have not yet been tested:

“Laser heating chamber is probably the most significant problem: can we contain hydrogen gas, our fuel, since it is heated by a laser beam to temperatures above 10,000 K, while keeping the walls of the chamber cold? Our models say it is possible, but full-scale experimental testing is currently not possible because we have not yet built the right 100 MW lasers. ”

Although much of the technology in this proposed mission architecture – and other similar proposals – is still under theory and development, there is no doubt about their potential. Reducing the time it takes to get to Mars in a few weeks, not months, will solve the two biggest problems for missions to Mars – logistical and medical considerations.

In addition, the creation of a system of rapid transit between Earth and Mars will accelerate the creation of infrastructure between Earth and Mars. This could include a Gateway-like space station in orbit around Mars, such as the Mars base camp offered by Lockheed Martin, as well as laser mass to slow down incoming spacecraft. The presence of these facilities will also accelerate plans to create a permanent human presence on the surface. As Professor Higgins concluded:

“The 45-day study of Mars design, led by Emanuel, was motivated by a study of other, closer applications of phased array laser technology being developed by Philip Lubin’s team. The ability to deliver energy deep into space with a laser would be a destructive technology of motion and power. Our study looked at the laser thermal approach, which looks encouraging, but the laser technology itself is really changing the game. ”

Originally posted on The universe today. Lasers can send missions to Mars in just 45 days

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