A Catalyst for Lunar Radio Astronomy
History was made today.
The Intuitive Machines Odysseus lander successfully touched down on the Lunar surface, south polar region, at 6:24 PM Eastern Time on Thursday, February 22, 2024. This was the first time a private US company has ever landed a spacecraft on the Moon, and the first US Lunar landing since 1972.
Left: The Intuitive Machines Odysseus Lander. / Right: The Odysseus Lander taking off in a SpaceX Falcon 9 Rocket.
The Radio wave Observation at the Lunar Surface of the photoElectron Sheath (ROLSES) instrument, one of six NASA scientific payloads onboard Odysseus, was developed by two DeepSpace Technologies executive staff members while they were still at NASA. The instrument is a 4-channel polyphase spectrometer designed to study the dynamic radio energy environment near the lunar surface between 10kHz and 30 MHz.
NASA Heritage, DeepSpace Foundations…
The engineering design and build of ROLSES was led by two NASA Goddard Space Flight Center veterans - Dr. Damon Bradley (20 years) and Dr. William (Bill) Farrell (32 years), Founder and Chief Scientist of DeepSpace Technologies, respectively.
The ROLSES science team was originally led by Dr. Robert (Bob) MacDowall, who retired from NASA-GSFC in 2022. ROLSES is currently led by Dr. Nat Gopalswamy/NASA-GSFC.
Left: The ROLSES main computer. / Right: The ROLSES instrument undergoing electromagnetic testing at NASA Goddard Space Flight Center, prior to delivery to Intuitive Machines.
A tale of two spectra…
The ROLSES instrument is a digital spectrometer - actually four of them, that all run in parallel and simultaneously, one assigned per antenna. But this isn’t any ordinary spectrometer. ROLSES is designed to measure the Lunar radio frequency environment in two drastically different but overlapping frequency bands - between near-DC and 1.875 MHz, but also 1.875 MHz to 30 MHz. The low frequency operation helps it precisely analyze the photoelectron sheath -radio waves resulting from energetic electrons radiated from the Lunar surface in response to incident solar UV and X rays (Farrell, 2013), and the high frequency operation helps it characterize the local radio frequency interference (RFI) environment, similar to what Damon and team accomplished on the Soil Moisture Active Passive (SMAP) spectrometer (Bradley, 2010). In fact, the ROLSES spectrometer is a more advanced version of the SMAP spectrometer that has been working since 2015 in a polar orbit around Earth.
The ROLSES frequency plan. Each antenna signal is split into low and high band channels, and spectrally analyzed for determining photoelectron sheath behavior and radio frequency interference detection.
Multiple Roles on ROLSES…
Damon served several roles on the rapidly-developed mission. As science Co-investigator, he helped colleagues Bill and Bob with the original instrument proposal submitted to the NASA Commercial Lunar Payload Services (CLPS) program in 2018, and negotiated an instrument concept proposed by Bill that started on a single sheet of paper in 2019. Damon then went on to staff and direct the newly-awarded effort with a small team of engineers from his own Instrument Electronics branch, (which he also simultaneously served as the branch chief) who had prior experience developing robotic servicing systems and Lunar science instruments. Damon also served a critical role as digital signal processing (DSP) lead, and invented a specialized Field-Programmable Gate-Array (FPGA)-based spectrometer - the scientific brain of the instrument to analyze the local Lunar radiofrequency environment.
Bill served as the analog and measurement architect of ROLSES and the deputy instrument scientist, while also running a laboratory at NASA-GSFC that studies planetary electric field phenomena.
Damon in the lab with the ROLSES Engineering Test Unit. / ROLSES flight unit mounted on the Odysseus Lander. / ROLSES engineering test unit on the bench. / Delivery of the ROLSES flight Unit on Damon’s last day at NASA-GSFC.
Model-Based Signal Processing Design…
ROLSES had to be completely developed and delivered in 2 years time - unprecedented speed for a NASA mission. To help with the complex bits required, the FPGA-based Digital Signal Processor (DSP) was developed via a combination of hand-coded VHDL, and Mathworks Simulink HDL Coder. A DSP design that would have otherwise taken more than a year to develop using traditional methods, was completed in 4 months time.
Evolution of the ROLSES spectrometer design - from functional block diagram to chip architecture.
Setting the Tone For Deep Space Exploration…
The successful launch of the Odysseus lander and the NASA ROLSES instrument represents a significant advancement in humankind’s efforts to explore and utilize the resources of the moon. This achievement underscores the collaborative efforts of Intuitive Machines and NASA in pushing the boundaries of space exploration and bolstering our capabilities for sustainable lunar exploration.
With the Odysseus lander and the NASA ROLSES instrument now operating on the Moon, the stage is set for a new era of lunar exploration and radio astronomy. This successful launch paves the way for a future where the moon plays a pivotal role in expanding our understanding of the cosmos and unlocking the potential for sustained human presence beyond Earth.
For more information and updates on this historic mission, please stay tuned to the latest developments from Intuitive Machines and NASA.
https://www.reuters.com/technology/space/us-achieves-first-moon-landing-half-century-with-private-spacecraft-2024-02-23/
https://www.bbc.com/news/science-environment-68377730
References
Farrell, W. M., A. R. Poppe, M. I. Zimmerman, J. S. Halekas, G. T. Delory, and R. M. Killen (2013), The lunar photoelectron sheath: A change in trapping efficiency during a solar storm, J. Geophys. Res. Planets, 118, 1114–1122, doi:10.1002/jgre.20086
D. Bradley et al., "Radio-frequency interference (RFI) mitigation for the soil moisture active/passive (SMAP) radiometer," 2010 IEEE International Geoscience and Remote Sensing Symposium, Honolulu, HI, USA, 2010, pp. 2015-2018, doi: 10.1109/IGARSS.2010.5652482.
