This study investigates the behavior of rockfall protection on a reinforced concrete semicircular shed against impulse excitation forces by using finite element software ABAQUS and experimental analysis on a free-fall impact test machine. There is limited field knowledge about the response of rockfall protection reinforced concrete semicircular sheds under free-fall impact. The experiments are carried out through the 0.5-m center-to-center diameter of a semicircular reinforced concrete (RC) shed which has a 1.2-m length. The shape of the impactor is cylindrical with a free-fall height of 2.4 m on a semicircular reinforced concrete shed from a free-fall impact test machine. Conventional explicit analysis in finite element software ABAQUS was employed. The concrete damaged plasticity, Johnson-Cook plasticity, and Drucker-Prager models were used to mimic the reaction behavior of concrete, reinforcement, and soil, respectively. The findings from the finite element program ABAQUS were compared to the experimental data, which were found to be in close agreement. Furthermore, the simulation was carried out on the effect of important parameters such as variation in the velocity of the impactor, lining thickness, and length of the RC shed to predict the behavior of reinforced concrete shed.

The primary objective of the Lunar Crater Observation and Sensing Satellite (LCROSS) was to confirm the presence or absence of water ice in a permanently shadowed region (PSR) at a lunar pole. LCROSS was classified as a NASA Class D mission. Its payload, the subject of this article, was designed, built, tested and operated to support a condensed schedule, risk tolerant mission approach, a new paradigm for NASA science missions. All nine science instruments, most of them ruggedized commercial-off-the-shelf (COTS), successfully collected data during all in-flight calibration campaigns, and most importantly, during the final descent to the lunar surface on October 9, 2009, after 112 days in space. LCROSS demonstrated that COTS instruments and designs with simple interfaces, can provide high-quality science at low-cost and in short development time frames. Building upfront into the payload design, flexibility, redundancy where possible even with the science measurement approach, and large margins, played important roles for this new type of payload. The environmental and calibration approach adopted by the LCROSS team, compared to existing standard programs, is discussed. The description, capabilities, calibration and in-flight performance of each instrument are summarized. Finally, this paper goes into depth about specific areas where the instruments worked differently than expected and how the flexibility of the payload team, the knowledge of instrument priority and science trades, and proactive margin maintenance, led to a successful science measurement by the LCROSS payload's instrument complement.