Thanks to President Obama’s directive, NASA has no current plans to return humans to the moon. However, as is common with space policy, this is subject to change, especially if a new president decides that it must be.
The question is, if a future president directs NASA to return to the moon or if somehow Congress forces the issue during the Obama administration, how would the space agency carry it out?
The most commonly discussed scenario, now that President Bush’s Constellation program is on the ash heap of history, could be called “the heavy lift option.”
When NASA first sent astronauts to the moon it build a gigantic heavy lift rocket called the Saturn V, which sent three astronauts in the Apollo command and service module into lunar orbit along with a lunar module. Two of the astronauts boarded the lunar module and took it to the lunar surface for stays of from a few hours to three days before returning to the orbiting Apollo which they used to return to the Earth.
The modern heavy lift option, described in the “Moon First” scenario in the Augustine Commission Report, requires two heavy lift spacecraft, one to take four astronauts into lunar orbit in the Orion space craft, one to take a landing module into lunar orbit. The Orion would dock with the landing module, the astronauts would transfer to the lunar module and then take it to the lunar surface to explore for about a one week stay.
If a future president were to direct NASA to return to the moon, the heavy lift option would use two Space Launch System heavy lift rockets now being developed by the space agency, the Orion, and a lunar lander to be developed. NASA’s Pad 39B, used to launch both Saturn Vs and the space shuttle, is currently being retrofitted for SLS launches, according to NASA. Pad 39A, also used for Saturn Vs and space shuttles, which may be developed into a multi use commercial launch pad that might also be used for SLS launches, according to USA Today. NASA would doubtless be keen to launch the two parts of the lunar expedition as close together as possible.
The advantage of this scenario lays in its simplicity and familiarity. Despite the fact that it uses two launches rather than one, it tracks closest to the way NASA went to the moon before.
The main disadvantage of the heavy lift scenario is up front expense. NASA has to develop the heavy lift Space Launch System before it can send astronauts to the moon or anywhere else in deep space. While having the throw weight capability of an SLS would be useful for a wide variety of missions, some of them unmanned, the fact remains is that the space agency must spend a not insignificant amount of money to get the heavy lifter on line. In an era of lean budgets, this is not a frivolous consideration.