Suited for Spacewalking pdf - Virtual Astronaut

d ay or tw o, Ap o llo spacesuit materials on ly had tos u rv i ve 10 to 20 hours of use. Fu t u re Mart i a ne x p l o re r s , h ow eve r, w i ll remain on the planet form a ny months to a year or more, and their suits willneed to be con s t ructed of rugged materi a l s .PurposeThis apparatus will measure the abrasion of fabricsand other suit materials exposed to simu l a t e dMartian sediment.PrincipleTest samples are placed in a rock tumbler or a speciallyconstructed tumbler similar to the one shownon the proceeding page. Simulated Martian sedimentis placed in the drum and the rotating motioncauses the sediment to abrade the samples.Materials and Tools ChecklistWooden base (12" x 24" x 1")Electric motor with pulley(use motor with low rpms)Pulley beltPlastic food jar (1 gallon)Fabric abrasion tester in use at the NASA Johnson Space Center. The whitedrum contains an inflated cylinder made from the outer fabric ofa spacesuit.The drum also contains lunar sediment simulant. An electric motor with apulley drives the drum.Four castersWood block stopsFabric samplesMasking tapeMartian sediment simulantOperationThe device shown on the previous page is a homemaderock tumbler. It is constructed from a plasticjar of the kind supplied to cafeterias and restaurantswith various food stuffs such as relishes or mayonnaise.A motor, pulley, and rubber band belt rotatethe jar. The jar rests on inverted casters and is heldin place with stops at the ends. Squares of fabricsamples are taped to the inside walls of the jar anda measured quantity of Martian sediment simulantis placed in the jar. The jar is allowed to rotate for aday or two and the fabric samples are removed forc om p a ri s on with fresh samples. R e d d i s h - b row nvolcanic rock used for landscaping can be used formaking Martian sediment simulant. Bags of therock will have small amounts of abraded sedimentat their bottoms or you can crush the rocks to a finesoil-like material. Be sure to wear eye protectionand gloves. Use a hammer to smash the rocks. Sortout and discard the larger pieces to leave just thesandy to powdery material behind.Tips• Look for an electric motor at an electric partsstore. It may also be possible to find a suitablemotor in an old appliance. Casters can beobtained at a hardware store.• Examine fabric samples for signs of wear such astears and holes. If a sample is opaque, place it onthe lighted stage of an overhead projector to lookfor holes and thin areas.• If solid materials are to be tested,do not test fabricsat the same time. The solid materials maydamage the fabric,making it difficult to interpretthe results.• Estimate the number of rotations of the "rocktumbler" jar by counting how many times the jar5 8 • Suited for Spacewalking An Activity Guide for Technology Education, Mathematics, and Science, EG- 1 9 9 8 - 0 3 - 1 1 2 - H Q