A report proposes the use of cold hibernated elastic memory (CHEM) foam structures to cushion impacts of small (1 to 50 kg) exploratory spacecraft on remote planets. Airbags, which are used on larger (800 to 1,000 kg) spacecraft have been found to (1) be too complex for smaller spacecraft; (2) provide insufficient thermal insulation between spacecraft and ground; (3) bounce on impact, thereby making it difficult to land spacecraft in precisely designated positions; and (4) be too unstable to serve as platforms for scientific observations. A CHEM foam pad according to the proposal would have a glass-transition temperature (Tg) well above ambient temperature. It would be compacted, at a temperature above Tg, to about a tenth or less of its original volume, then cooled below Tg, then installed on a spacecraft without compacting restraints. Upon entry of the spacecraft into a planetary atmosphere, the temperature would rise above Tg, causing the pad to expand to its original volume and shape. As the spacecraft decelerated and cooled, the temperature would fall below Tg, rigidifying the foam structure. The structure would absorb kinetic energy during ground impact by inelastic crushing, thus protecting the payload from damaging shocks. Thereafter, this pad would serve as a mechanically stable, thermally insulating platform for the landed spacecraft.
This work was done by Witold Sokolowski and Marc Adams of Caltech for NASA's Jet Propulsion Laboratory. To obtain a copy of the report, "Novel Precision Soft Lander (PSL)," access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Mechanics category. NPO-30435.
This Brief includes a Technical Support Package (TSP).
Soft Landing of Spacecraft on Energy-Absorbing Self-Deployable Cushions
(reference NPO-30435) is currently available for download from the TSP library.
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Overview
The document is a technical support package prepared under the sponsorship of NASA, detailing an innovative approach to soft landing spacecraft using energy-absorbing self-deployable cushions. The work is attributed to inventors Marc A. Adams and Witold M. Sokolowski and is part of a broader effort to enhance landing systems for small landers, particularly in planetary exploration missions.
The core of the proposal revolves around the Precision Soft Lander (PSL) concept, which utilizes cold hibernated elastic memory (CHEM) foams as structural elements. These foams can be compacted to less than 10% of their volume for storage during launch and flight. Upon atmospheric entry, the structure deploys by utilizing heat generated from aerodynamic forces, negating the need for additional heating systems. This deployment mechanism not only increases the drag coefficient of the entry body, thereby reducing its speed, but also provides excellent thermal protection for the instrument package on the lander due to the foam's low thermal conductivity.
The PSL concept addresses several challenges associated with traditional landing methods, such as airbags, which are often too complex and costly for small landers (1 to 50 kg). Airbags can lead to bouncing upon impact, making precise landings difficult, and they do not offer sufficient thermal insulation against cold ground temperatures. In contrast, the PSL system promises a soft, stable, and precise landing, with the foam structure rigidizing in the cold atmosphere before impact, ensuring a stable landing platform.
Additionally, the document discusses a microspacecraft concept designed to function like a black box for spacecraft. This microspacecraft would continuously store critical data from the main spacecraft and, upon detecting serious conditions, would separate and transmit this data back to Earth. This system enhances data retrieval capabilities during catastrophic failures, providing valuable information without the need for physical recovery.
Overall, the document outlines a significant advancement in landing technology for small spacecraft, emphasizing simplicity, cost-effectiveness, and improved safety through innovative materials and design. The proposed solutions aim to facilitate future exploration missions to planetary bodies and small celestial objects, enhancing our understanding of these environments.
