A document proposes systems of sensors encased in cold hibernated elastic memory (CHEM) structures for exploring remote planets. The CHEM concept was described in two prior NASA Tech Briefs articles, including “Cold Hibernated Elastic Memory (CHEM) Expandable Structures” (NPO-20394), Vol. 23, No. 2 (February 1999), page 56 and “Solar Heating for Deployment of Foam Structures” (NPO-20961), Vol. 25, No. 10 (October 2001), page 36. To recapitulate: Lightweight structures that can be compressed for storage and later expanded, then rigidified for use are made from foams of shape-memory polymers (SMPs). According to the instant proposal, a CHEM sensor structure would be fabricated at full size from SMP foam at a temperature below its glass-transition temperature (Tg). It would then be heated above Tg and compacted to a small volume, then cooled below Tg and kept below Tg during launch, flight, and landing. At landing, the inelastic yielding of the rigid compacted foam would absorb impact energy, thereby enabling the structure to survive the landing. The structure would then be solar heated above Tg, causing it to revert to its original size and shape. Finally, the structure would be rigidified by cooling it below Tg by the cold planetary or space environment. Besides surviving hard landing, this sensor system will provide a soft, stick-at-the-impact- site landing to access scientifically and commercially interesting sites, including difficult and hard-to-reach areas.
This work was done by Witold Sokolowski and Eric Baumgartner of Caltech for NASA’s Jet Propulsion Laboratory.
This Brief includes a Technical Support Package (TSP).
Foam Sensor Structures Would Be Self-Deployable and Survive Hard Landings
(reference NPO-30654) is currently available for download from the TSP library.
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Overview
The document outlines a technical support package for a New Sensor Delivery System developed by NASA's Jet Propulsion Laboratory (JPL) under contract with the National Aeronautics and Space Administration (NASA). The primary focus of this proposal is the creation of a prototype sensor that is self-deployable and can endure high impact loads, simulating conditions experienced during landings on planetary surfaces, particularly Mars.
The innovative sensor system is constructed using Cold Hibernated Elastic Memory (CHEM) technology, which incorporates shape memory polymers in an open cellular structure. This design allows the sensor to be compacted into a small volume for launch and storage, and upon landing, it can expand to deploy its components. The document emphasizes the importance of conducting drop tests to evaluate the impact properties of the CHEM-based sensor system, comparing its energy absorption capabilities to conventional designs used for hard landings.
The motivation behind this development stems from the need for effective in-situ exploration of planetary surfaces, particularly in hard-to-reach areas that may be scientifically significant, such as potential water seepage sites identified by the Mars Global Surveyor orbiter. Traditional exploration methods, like mobile rovers, face challenges in accessing rugged terrains due to mobility and power constraints. In contrast, the proposed sensor network can be scattered across diverse locations, enabling comprehensive data collection without the limitations faced by rovers.
The document also highlights the potential applications of this sensor network in future planetary exploration missions aimed at understanding the geology and climate history of Mars and other celestial bodies. By deploying a network of lightweight, low-volume sensors, researchers can achieve detailed in-situ exploration at a sub-meter level, which has been limited in past missions.
In summary, this technical report presents a novel approach to planetary exploration through the development of a self-deployable sensor system that can withstand the harsh conditions of planetary landings. The CHEM technology promises to enhance the capabilities of future missions, allowing for more extensive and effective exploration of planetary surfaces. The work is a collaborative effort by inventors Eric T. Baumgartner and Witold M. Sokolowski, with the support of JPL's Intellectual Assets office.
