The decision signals what could be a huge change in NASA policy. Griffin repeatedly has rejected the notion of extending the shuttle era beyond its 2010 retirement date, arguing it could cripple the fledgling Constellation program, a system of new rockets and capsules meant to replace the shuttle in 2015.
But Griffin has been under enormous external pressure. Sen. John McCain recently asked the White House to stop dismantling parts of the shuttle program for at least a year. At the same time, eroding relations with Russia have motivated lawmakers to find a way to fill the five-year gap between the shuttle's retirement and the maiden voyage of Constellation in 2015. The current plan calls for NASA to buy Russian spacecraft during the gap.
One NASA official said such "what-if studies" represent "prudent planning," especially in light of suggestions made by McCain, the Republican presidential nominee, who would dictate the agency's future if he captures the White House.
But the email, sent on Wednesday, August 27, by John Coggeshall, manager of "Manifest and Schedules" at Johnson Space Center in Houston, suggested that the analysis was more than just a contingency study.
"We want to focus on helping bridge the gap of US vehicles travelling to the ISS as efficiently as possible," it said.
The upcoming study raised the idea of retiring one of the three remaining orbiters, possibly for spare parts. "(We) don't necessarily need all 3 orbiters either," said the email. "We have been encouraged not to focus on a certain set of assumptions or costs," said the email.
But cost has been the exact reason why Griffin has dismissed the idea of extending the shuttle era. To have enough money to build Constellation's Ares 1 rocket and Orion crew capsule, NASA must spending stop money on shuttle flights. At one point last year, he estimated that it would cost as much as $4 billion a year to fly the shuttle beyond 2010.
NASA' current budget is about $17 billion.
"Continuing to fly the Shuttle beyond 2010 does not enhance U.S. human spaceflight capability, but rather delays the time until a new capability exists and increases the total life cycle cost to bring the new capability on line," he told Congress in November.
Another worry: NASA already has begun unplugging parts of the shuttle system. It has already terminated many contracts with vendors who make shuttle parts and NASA facilities already have begun converting its systems to handle the new Constellation program.
Wayne Hale, a NASA deputy assistant administrator and until recently the shuttle-program manager, has said that this fall marks the point of no return. That's when NASA is supposed to start ripping out the giant welding equipment and other machinery at Michoud Assembly Facility in New Orleans, which makes the shuttle's giant external fuel tank.
In a blog posted Thursday, Hale said that flying shuttle and building Constellation would strain NASA's budgets and overextend its workforce. "Hey, I am the biggest shuttle hugger there is. I think it is the best spacecraft ever built. But I also deal in the real world," he wrote.
"Where does the money come from? Where do the people -- who should be working on the moon rocket -- where do they come from? We started shutting down the shuttle four years ago. That horse has left the barn," he wrote.
Read the email: Download nasa_email.doc