Space-truckin’: LLNL delivers ‘Deep Purple’ optics for NASA’s Pathfinder mission

03 Jul 2024

Optical payload utilizes new design for UV and SWIR monolithic telescope.

Machine head: lead designer Darrel Carter designed the Deep Purple payload.

Lawrence Livermore National Laboratory’s space hardware team has delivered a payload for NASA’s Pathfinder Technology Demonstrator-R satellite. LLNL developed the optical payload, called Deep Purple – named after the heavy rock pioneers – that utilizes a new design for a UV and SWIR monolithic telescope.

The mission is intended to demonstrate simultaneous monolithic UV and SWIR optical sensing from space for the first time via two co-boresighted, 85 mm aperture monolithic telescopes using a new compact custom electronics module and a novel, lightweight, carbon-composite optical housing and radiator.

The satellite is scheduled to launch in the summer of 2024 aboard SpaceX’s Transporter-11 mission from Vandenberg Space Force Base in California.

Designed and delivered in a year for less than $1 million, Deep Purple will also observe UV and short-wave infrared light from high-UV stars and the galactic bulge. The scope’s dual optical module and electronics are contained in a 250 x 150 x 100 mm package.

LLNL’s monolithic optics are a novel line of compact Cassegrain telescopes constructed out of a single piece of fused silica. This design allows for a compact telescope that can endure the harsh environments of launch and outer space.

“The optical package also is highly configurable, which gives us the ability to mix and match different sensors and optics within the same infrastructure to meet a variety of mission needs,” said Jordan Smilo, the LLNL Deep Purple principal investigator and space hardware lead mechanical engineer.

“Deep Purple serves as an example of how the Lab’s Space Program combines the R&D nature of LLNL with the deployment of innovative technology and its national-security mission at heart,” said John Ganino, associate program leader for space hardware at the Laboratory and system engineer lead for Deep Purple. “We believe Deep Purple will be the smallest space telescope providing both SWIR and UV imaging in space.”

In January, the Space Hardware team qualified the Deep Purple payload.

Heavy metal traded

“This satellite is a 6U-sized space vehicle [the volume of six 100 mm CubeSats]. The Deep Purple payload was limited to 5 kilograms. We also had the added challenge of incorporating our own electronics control module within the same volume,” Smilo said. “We also traded the heavier invar material, a nickel-iron alloy, that’s typically used for optical housings for a novel, lightweight, carbon-fiber-nano-tube-composite housing,” Smilo said.

Once operational, Deep Purple will simultaneously observe the UV and SWIR light from high-UV stars and the Milky Way’s galactic bulge. Such simultaneous imagery gives way to observing time-domain astronomical events, such as Fast Blue Optical Transients, a phenomenon recently discovered and yet to be understood.

Deep Purple also will attempt to demonstrate real-time space domain awareness using these sensing bands. The Space Program at LLNL continues to demonstrate its leadership in developing and delivering small satellite tools and capabilities.

“Deep Purple may be small but the information it will reveal for the first time could make a huge impact on space-domain awareness,” said Ben Bahney, program leader for the space program at Lawrence Livermore. “The team’s ability to deliver such an incredible tool in such a short amount of time, while meeting NASA’s rigorous requirements is another impressive achievement.”