Sunday, September 16, 2007

Photonic laser thruster

The photonic laser thruster, created by the Bae Institute in California, overcomes the inefficiency of photon particles producing thrust by bouncing them many times between two mirrors.

Photon particles have been considered inefficient for producing thrust because they have zero mass and no electric charge. The PLT system overcomes the inherent photonic inefficiency by bouncing photons many times between two mirrors.

On Dec. 21, 2006, Bae used a photonic laser and a sophisticated photon beam amplification system to demonstrate that photonic energy could generate amplified thrust between two spacecraft by bouncing photons many thousands of times between them. Repeated experiments since then have confirmed the results.

The patent-pending PLT was built and monitored with off-the-shelf laboratory components at the Southern California laboratory of the Bae Institute, which was founded in 2002 by Bae to develop innovative space and medical technologies for commercial and government applications. Bae has pursued advanced propulsion concepts such as antimatter and fusion propulsion for more than 20 years at SRI International, Brookhaven National Lab and the AFRL.

With an amplification factor of 3000, the photon thrust generated from the egg-sized laser head in the PLT prototype is equivalent to the thrust that can currently only be generated by orders-of-magnitudes larger and heavier industrial or weapons-grade lasers.

Although PLT can be used for a wide range of space applications, including accelerating spacecraft to near light speed, Bae has more immediate goals. He plans to include PLT in a photon tether formation flight (PTFF), another of his patent-pending ideas for controlling spacecraft flying in formation with nanometer precision. By integrating PLT and space tethers, PTFF will enable the creation of large telescopes and synthetic apertures in space for high-resolution earth or space monitoring. Bae said PTFF promises precision 100,000 times greater than existing formation flying spacecraft missions, notably the Proba-3 currently planned by the European Space Agency.

As a result of the successful PLT demonstration, thrust power requirements for a wide range of NASA spacecraft formation flight configurations, such as SPECS and MAXIM, are well within today's space power budgets. No other propellants are needed with PLT, resulting in mass energy savings, extended spacecraft missions, and contaminant-free operation for highly precise sensors, Bae said.

Although built on a shoestring budget, the maximum photon thrust was demonstrated to be 35 uN, which is already close to, or sufficient power for many envisioned space missions. The Bae Institute is now seeking funding to scale up and construct space flight-ready PLT systems.

In addition to conventional formation flying, fractionated space architectures can benefit tremendously from the versatility and flexibility of a tightly controlled PLT system.