Until the Apollo astronautsbrought lunar soil samples to Earth during 1969-72, the belief was that theMoon''s dry, airless environment left the soil largely undisturbed. Reality ismuch harsher. A speck of Moon dirt. The strange shape tells a tale of violence:It results from the welding(焊接)of rock, mineral and glass by the heat of micrometeoroid impacts. Micrometeorites,many smaller than a pencil point, constantly rain onto the surface at up to100,000 km/hr (about 62,000 mph), chipping off materials or forming microscopic(tiny)impact craters(坑). Some meltthe soil and vaporize and re-condense as glassy coats on other specks of dust. Impacts weld debris into"agglutinates.(attach)" Complicated interactions with the solarwind convert iron in the soil into myriads(mutiple) of "nano-phase(superhard material)" metallic iron grainsjust a few nanometers wide. These processes form the "regolith" --Greek for stone blanket (litho + rhegos) -- covering the Moon''s surface.
The Apollo specimens areAmerica''s Crown Jewels and are doled(施舍)out in ultra-small samples toscientists who can demonstrate that nothing else will do for high-valueexperiments. Renewed interest in lunar exploration in the late 1980smeant that lunar simulants were needed to test schemes(计划) for building structures on the Moon or forextracting oxygen and other materials. That led to JSC-1 in 1993, madeof basaltic volcaniccinder cone deposits from a quarry near Flagstaff, AZ. The 25-ton lot --distributed in 50-pound bags -- proved popular.
MSFC is developing three newsimulants. Two will represent mare(thelarge dark areas on the Moon)and polar highlands regions. A third will represent the glassy, sharp, jagged(锯齿状的) edges of regolith thattest the best of hardware(指器械) andhumans. But matching every location on the Moon would require large numbers of small,unique, expensive batches.
"Instead, we willdevelop root simulants and manufacture specific simulants from these, but alsoenable investigators to enhance the products as needed," McLemore added."I liken this process to baking a cake: depending on the type of cake youwant, you need certain ingredients for it to come out right and taste right.Getting the recipe right whether for a cake or lunar simulants iscritical." For example, the new mare simulant will be enriched withilmenite(a mineral), a crystalline iron-titanium oxide. Source materials used toproduce the three simulants will potentially come from locations as diverse asMontana, Arizona, Virginia, Florida, Hawaii, and even some international sites.