In the design of systems to absorb the landing impact energy of space vehicles, such as the system which will be used to protect the Lunar Excursion Module of the Apollo spacecraft in touching down on the moon, the specific energy absorption (energy absorbed divided by the weight of the material deformed) is not necessarily the primary factor. Other factors which must be considered include the compatibility of the deforming structure with its support, the packaging volume of the system, the control of penetration into the landing surface, and the desirability of the system with respect to tip-over stability and maximum permissible acceleration. These factors can lead to consideration of systems which do not employ energy absorbers of maximum efficiency. Materials improvements leading to better energy absorption in these systems could result in significant gains, particularly for the systems having relatively inefficient absorbers. In addition, it is recommended that materials be improved by decreasing their elastic bounce-back and increasing their resistance to the effects of the rocket exhaust and the space environment. Such materials improvements may play a major role in the selection of energy-absorbing systems.