AITC News

Published in the RSAA Lunations
Vol1 Issue41 1–30 June 2023

Fresh off the plane from sunny (and smoggy) Los Angeles, I’ve just completed a few months’ internship with the Optical Communications group at NASA’s Jet Propulsion Laboratory (JPL). Famous for its Mars rovers and probes like Voyager, JPL also has a rich history of pioneering the spaceflight communication for supporting these missions - a fact we are constantly reminded of at Mount Stromlo, given the that Tidbinbilla Deep Space Network station is just down the road. Because of the immense promise for optical communications in deep space comms, JPL has been a trailblazer in this field since the late 1990s, and being able to work with the group was a fantastic experience. JPL’s optical communications group is now leading a number of current and future spaceflight instruments, such as on-board the Psyche probe, which will be launched towards the asteroid belt later this year to investigate a metal-rich asteroid of the same name. Psyche’s laser terminal will demonstrate an optical link to the historic 200” Hale Telescope at Palomar Observatory just outside Los Angeles. JPL’s optical ground station at Table Mountain Observatory, only an hours drive from Los Angeles, will also be one of the primary ground stations to support the laser link with the Artemis II mission, NASA’s first crewed return to the moon since the Apollo program.

My research at JPL has been to install a new type of atmospheric turbulence monitor at Table Mountain. Measuring turbulence is well-established in astronomy, but with optical communications now looking for the same capability, measuring daytime turbulence has emerged as a serious gap in our knowledge — that’s where my research comes in. Measuring daytime turbulence is tricky because we normally have to pick out stars amid a bright background, but at JPL I cheated by swapping out stars for a laser beam thanks to the recently launched Laser Communications Relay Demonstration, a NASA payload in Geostationary orbit launched late 2021. The narrow spectral linewidth from a laser allows us to easily filter out almost all of the bright sky background. This capability allows the instrument to provide real time turbulence data for the adaptive optics on the ground station whenever the satellite is communicating with Table Mountain, and through the exact same column of air as the ground station. As the instrument continues to run alongside the ground station we are hoping to produce some exciting and novel results in the near future.

You may have also noticed that our own optical ground station, just West of the CSO building, has grown substantially from just a concrete slab a few months ago. We are hoping to have everything complete in just a couple more months and I’m eager to be commissioning our own facility and applying some of what I’ve learnt at NASA to help build Mount Stromlo’s future as the hub for optical communications in Australia.

The opportunity to work at the Jet Propulsion Laboratory was nothing short of phenomenal and I owe a lot to the AITC, CSIRO, and particularly my supervisor, Francis Bennet. CSIRO’s involvement in the optical upgrade of the Tidbinbilla deep space network, and the AITC's bid to support the Artemis II mission with the Stromlo optical ground station has created strong ties with NASA and I’m fortunate to have benefited from these collaborations.

Marcus Birch

_{Picture: Marcus Birch with the rover}