* Options for commercial launch service to station
* Moon probe set to launch Thursday
* Panel to issue report in August
By Irene Klotz
CAPE CANAVERAL, Fla., June 17 (Reuters) - As NASA prepared to launch its debut mission in a program aimed at returning astronauts to the moon, a presidential panel on Wednesday began looking at alternative ways to get there and whether the United States should even go.
The Lunar Reconnaissance Orbiter, scheduled to launch from Cape Canaveral Air Force Station at 5:12 p.m. (2112 GMT) on Thursday, is designed to map the lunar surface so NASA can find safe and scientifically interesting landing spots for future human missions.
The United States is shifting the focus of its human space program from research and technology development in low-Earth orbit with the space shuttle and International Space Station to an exploration initiative. That would culminate in the return of U.S. astronauts to the moon in 2020 -- a half-century after the pioneering Apollo lunar landings of 1969 to 1972.
NASA plans to retire the shuttle fleet in 2010 after eight more missions to complete space station construction. It would then shift funding to ramp up development of a pair of expendable rockets, known as Ares, and a beefed-up Apollo-style capsule called Orion that can ferry crews to the moon and other destinations.
Orion's debut flight to the space station is targeted for 2015 -- five years after the shuttle stops flying.
With costs estimated at more than $100 billion for a lunar excursion and concerns about the five-year gap, President Barack Obama has ordered a top-level review of the U.S. human space program.
Hearings in Washington opened on Wednesday with commercial companies, NASA and other space advocates laying out options for flying astronauts to the space station and getting to the moon.
Panel members will also consider whether the moon should even be a destination. The panel, headed by retired Lockheed Martin Chief Executive Norm Augustine, is expected to issue a report in August.
At the meeting, United Launch Alliance, a Boeing (BA.N) and Lockheed Martin (LMT.N) joint venture that markets the unmanned Atlas and Delta rockets, pitched an upgraded version of its rockets to replace NASA's planned Ares booster, an option a NASA-backed study found to be less expensive.
But the consultancy that prepared the study cautioned that would only be cheaper if NASA dropped plans for a second Ares rocket, a heavy-lifter that could carry cargo to the moon.
NASA's original plan for the new exploration initiative, known as Constellation, was a complete program that folded together the cost of developing both versions of the Ares rocket, using one as a predecessor for the other.
"When one starts contemplating replacing pieces of that architecture, all kinds of things begin to happen," said Gary Pulliam of The Aerospace Corporation.
Another company, Space Exploration Technologies, known as SpaceX, proposed another alternative to carry crews.
SpaceX founder Elon Musk said his firm's Dragon capsule, already purchased by NASA to haul cargo to the space station, could be used to transport astronauts by adding an escape system and making minor upgrades.
"The whole purpose of SpaceX from the beginning has been human space flight. That's why I created it," said Musk. "Dragon has five windows. You don't need windows for cargo." (Editing by Jane Sutton and Peter Cooney)