As technology advances, ideas that once seemed like science fiction are coming closer to reality. One such concept is space lasers — and while they might sound like futuristic weapons, scientists are exploring how they could be used to protect Earth from potential dangers like asteroid impacts.
In a new study, researcher Adam Hibberd from the Initiative for Interstellar Studies in London examines where space lasers might be best deployed to maximize their usefulness and minimize risks. Published on the arXiv preprint server, Hibberd’s paper focuses on the DE-STAR system — a proposed laser array designed to protect Earth by deflecting dangerous objects such as asteroids.
What Is DE-STAR?
DE-STAR, which stands for Directed Energy Systems for Targeting of Asteroids and exploRation, is a concept developed in 2013 that envisions using a modular array of lasers powered by solar cells. These lasers could generate enough energy to heat the surface of an asteroid to 3,000 Kelvin, a temperature that would cause the object to vaporize or change course. The system could also potentially propel spacecraft through space.
The DE-STAR concept has been further refined over the years, with variations such as DE-STARLITE, a smaller, mobile version that could be sent close to an asteroid to protect Earth from collision threats.
The Challenge of Safe Deployment
While the idea of space lasers may sound exciting, one major concern is the potential misuse of such technology. A laser array as powerful as DE-STAR could theoretically be turned into a weapon. A large array, such as the DE-STAR 4, could generate tens of gigawatts of energy, posing a risk if it were aimed at Earth.
To mitigate this danger, Hibberd’s study suggests placing the laser arrays far from Earth. By positioning the lasers at a safe distance, the energy they emit would weaken by the time it reached Earth, reducing the risk of accidental or deliberate harm.
According to the study, a DE-STAR 0 to 2 array, the smallest configurations, could be safely deployed at around 1 astronomical unit (AU) from the sun (the distance from Earth to the sun). Larger, more powerful arrays would need to be stationed much farther away. For example, a DE-STAR 4 array would have to be positioned 30 to 40 AU away — beyond the orbit of Neptune — and even further for ultraviolet systems, potentially up to 70 AU from the sun.
Strategic Placement in Space
The study also considers alternative locations where the lasers could be deployed without posing a threat to Earth. Lagrange points, which are gravitationally stable regions in space, are one option. For smaller arrays, the sun-Earth Lagrange points L4 and L5, located about 400,000 kilometers from Earth, could serve as deployment sites without the need for onboard propulsion systems to keep the arrays in place.
However, for larger arrays, these points may not provide enough distance for safe deployment. In such cases, the arrays might need to be placed beyond the asteroid belt, or even near the orbit of Jupiter, depending on their size and power.
A Balancing Act for the Future
As the possibility of space lasers becomes more realistic, the international community will need to address the potential risks and rewards. While treaties are in place to prevent the weaponization of space, not all nations have signed them, and some countries have been known to violate such agreements. Defining whether a space laser is a weapon or a defensive tool could become a contentious issue.
Regardless, protecting Earth from catastrophic asteroid impacts is an issue that humanity will eventually need to tackle. Whether through phased laser arrays like DE-STAR or other systems, finding a way to safeguard the planet from space threats will be essential for the future of civilization.
As Hibberd’s study demonstrates, it’s not too soon to begin considering the logistics of space lasers — including where to place them to ensure they benefit humanity without putting the planet at risk.
Gough, Evan. “There Are Plenty of Uses for Powerful Lasers in Space. But Where Should We Put Them?” Phys.org, Phys.org, 18 Sept. 2024, phys.org/news/2024-09-plenty-powerful-lasers-space.html. Accessed 19 Sept. 2024.
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