How lasers could help the ever-growing problem of space debris
NASA has so far identified over half a million pieces of space debris, some as small as flecks of paint orbiting Earth at around 17,500 mph. While the possibility of spacecraft getting hit by debris sends shudders down the spine of companies who pour billions into the industry, a professor in Canberra, Australia seems to have found a solution for the time being.
Orbital altitude packed with space debris would limit space endeavors
Professor Celine d'Orgeville of the Australian National University's (ANU) Research School of Astronomy and Astrophysics explained that at some point, debris would render certain orbital altitudes unusable for human endeavors. Logically, attaining higher altitudes would also mandate flying through the layer littered with dangerous debris. To put things into perspective, the picture alongside represents space debris countries generate per unit of payload put into orbit.
Kessler effect: Not-so-distant future where debris generates more of itself
NASA space debris expert Don Kessler observed that beyond a certain point, existing space vehicles will collide with debris, creating more debris, initiating a chain reaction. This phenomenon is called the Kessler effect. The phenomenon has been exaggerated and dramatized in the 2013 film Gravity.
Identifying space debris: First step to solving the problem
Professor d'Orgeville and her colleagues intend to start by tracking pieces of debris between one and ten centimeters in size using a laser guide star. A laser guide star is a telescope that can fire lasers at particles of specific materials in the atmosphere. The telescope is coupled to an adaptive optics system that astronomers have used for years to see through atmospheric turbulence.
Astronomers adjust telescopes in real-time using laser guide star data
Atmospheric turbulence is caused by pressure and temperature variations in the upper atmosphere. The turbulence is what makes stars twinkle. The laser guide star fires a laser of a specific wavelength to strike sodium particles in the stratosphere above the turbulence that bounces back. Photodetectors then calculate the reflected beam's distortions to quantify the turbulence. Astronomers can adjust telescopes to compensate for measured distortion.
Focusing deep space telescopes through atmospheric distortion is not easy
Without adaptive optics systems, it's nearly impossible to focus on deep space bodies. Data from the laser guide star is fed to complex algorithms and look-up tables that account for factors influencing distortion and output adjustment parameters for astronomical telescopes.
Locating using infrared lasers can help satellite operators dodge debris
Using the aforementioned adaptive optics system, d'Orgeville's team can adjust a telescope's deformable mirror in real-time at ANU's Mount Stromlo Observatory. The observatory fires pulses of a second, more powerful infrared laser through the telescope to find small debris and understand its path. The collected data is immediately relayed to satellite operators so they can perform avoidance maneuvers and dodge debris headed their way.
More powerful lasers could deflect debris pre-collision, delaying Kessler effect
In the future, d'Orgeville's team wants to help slow down the aforementioned Kessler effect. If the team detects two entities on a collision course to potentially create more debris, theoretically, they could fire a powerful 20-kilowatt infrared laser at one of them to deflect it slightly. Since there is no resistance to motion in space, a slight nudge could also send debris hurtling away.
Zapping debris out of existence isn't completely feasible yet
Why not obliterate debris with lasers, you ask? Well, d'Orgeville's team thought about that, too. However, one would need a very high-powered laser aimed accurately enough to burn the debris instead of fragmenting it. It's a dangerous proposition since active satellites share orbital altitudes with debris. Alternatively, satellite or spacecraft-mounted lasers could nudge debris into lower orbits that vaporize while entering the Earth's atmosphere.
Despite immense potential, d'Orgeville's has run out of government funding
D'Orgeville reportedly reassured those disturbed by her research that the lasers used by the ANU don't have the potential to zap airplanes and government satellites out of the sky. Despite pouring efforts into developing resourceful ideas, d'Orgeville's team has run out of government funding. She is currently seeking new sources to help her develop a demonstrable proposal. Elon Musk, are you listening?
