The last moon mission on NASA’s current schedule — a small, unmanned spacecraft that will study moon dust and the lunar atmosphere — is scheduled to launch on Friday from Wallops Island, Va., elating scientists who study the moon but highlighting political questions about what NASA should do next.

The Smart Car-size spacecraft, which NASA calls the Lunar Atmosphere and Dust Environment Explorer, will take 30 days to get into orbit around the moon, spend the next 30 days checking its equipment and proceed with scientific work for 100 days, searching for water molecules in the atmosphere and gathering data about the curious substance known as lunar dust. Then the probe, which goes by the acronym Ladee (pronounced laddie), will take a death plunge into the rocky surface of the subject it is studying.

The results of the scientific program could be helpful in preparing for future manned missions to the moon. Although NASA currently does not have such plans, some members of Congress have called on the space agency to return to the moon rather than pursuing its current space objectives.

Although there is wide agreement that NASA should ultimately aim for a manned flight to Mars, that goal is far off. The more immediate plan, which has been criticized on Capitol Hill, is to capture an asteroid and tow it closer to home so astronauts can visit it.