Tuesday, May 19, 2015

A Space Station With Laser Beams

          By Brian Orlotti

A research team working on a cosmic ray-detecting space telescope has announced their plans to use this tool to also detect orbital debris, as a prelude to testing a laser cannon on the International Space Station (ISS) designed to destroy space junk. The announcement interestingly parallels the US military's recent deployment of laser weapons for battlefield use.

Graphic of JEM-EUSO on the ISS.  The telescope, which is expected to be installed on the ISS in 2017, will observe brief flashes of light in the earth's atmosphere caused by particles arriving from deep space. Graphic c/o JEM-EUSO website

As outlined in the May 18th, 2015 DNews article, "Space Station Could Get Laser Cannon to Destroy Orbital Debris," the telescope, called the Extreme Universe Space Observatory (EUSO), is scheduled to be installed on the Japanese Experiment Module (also known as Kibo), of the ISS in 2017.

EUSO will be a first-of-its-kind mission concept focused on investigating high-energy cosmic rays and neutrinos by observing the streaks of ultraviolet light produced when these particles interact with Earth's atmosphere. EUSO, in essence, uses Earth's atmosphere as a detector.

Originally a European Space Agency (ESA) mission design, EUSO was to be hosted as an external payload on the ESA's Columbus module on the ISS. Although an initial design study was completed,  the ESA decided in 2004 not to proceed with the mission due to financial constraints. EUSO was then re-tasked as a payload to be hosted on board the Kibo module and the mission was renamed JEM-EUSO.

The Extreme Universe Space Observatory telescope. The telescope is a fast, highly-pixelized, large-aperture and large field-of-view digital camera, working in the near-UV wavelength range (330÷400 nm) with single photon counting capability. Graphic c/o JEM-EUSO in the USA

In the April 30th, 2015 Space.com article, "Space Station Could Get Laser Cannon to Destroy Orbital Debris," Toshikazu Ebisuzaki, an astrophysicist at the RIKEN Institute in Wako, Japan (one of the institutions taking part in EUSO), said that a team at RIKEN believe that EUSO could be used for space junk detection in addition to its cosmic ray work.

Once space junk is detected by EUSO, the RIKEN scientists have proposed using a coherent amplification network (CAN) laser to destroy it. A CAN laser utilizes many small lasers working together to generate a single powerful beam. This type of laser is currently being developed to drive particles to high speeds in particle accelerators.

The RIKEN scientists propose using the CAN laser to vaporize a thin layer off the surface of space debris. This vaporized layer would become a high-speed plasma (superhot gas) that would act like rocket exhaust, pushing the space junk away from the ISS to eventually burn up in Earth's atmosphere.

A full-scale version of their system would be armed with a 100,000-watt ultraviolet CAN laser that can fire 10,000 pulses per second, each pulse lasting one-tenth of one-billionth of a second. The RIKEN team says this system could have a range of about 100 km. The CAN laser would require about 8 kg of lithium-ion batteries.

They plan to deploy a small proof-of-concept version of their system at the ISS. This would consist of a miniature version of EUSO and a prototype 10-watt ultraviolet CAN laser firing 100 pulses per second. A RIKEN spokesman stated that the mini-EUSO telescope has been accepted as a project on the ISS and could perhaps be installed in 2017 or 2018, but the laser system has yet to be built.

Should the proof-of-concept and full-scale versions succeed, the RIKEN researchers suggest developing a satellite devoted solely to destroying space debris. They propose that the satellite could be placed into an orbit that traverses both of Earth's poles, enabling it to destroy debris all around the planet, and be armed with a 500,000-watt ultraviolet CAN laser able to fire 50,000 pulses per second. The researchers estimate that such a satellite could destroy one piece of debris every five minutes, or 100,000 pieces of space junk in a year.  Such a system would be a powerful weapon against the increasing threat of space junk.

The U.S. Navy Afloat Forward Staging Base (Interim) USS Ponce (AFSB(I)-15) with the Office of Naval Research (ONR)-sponsored Laser Weapon System (LaWS). The system was installed just prior to it's most recent deployment to the Arabian Gulf. in November 2014. US Navy photo c/o John Williams.

In November 2014, the US Navy deployed its first operational laser cannon in the field. The 30-kilowatt Laser Weapon System (LaWS) was installed on the amphibious transport ship USS Ponce and run through various tests, including destroying target ships and drones. The US Navy sees laser weapons as having major advantages over projectile ones, including a much lower cost per shot, no reload time, and no risk of running out of ammunition.

Although currently limited to defending against close-in targets due to limited power and a slow targeting system, the US Navy intends for next-generation LaWS to replace projectile-based systems like the Phalanx CIWS for defence against missiles and aircraft.

Brian Orlotti.
Laser weapons, long a science fiction staple, are now entering the realm of science fact. Also as in science fiction, they serve as instruments of both war and peace.

Brian Orlotti is a network operations centre analyst at Shomi, a Canadian provider of on-demand internet streaming media and a regular contributor to the Commercial Space blog.

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