WASHINGTON - NASA could extend space
shuttle operations to 2012 by adding three flights - at a cost of roughly $5 billion - without dramatically affecting
the agency's plan to return astronauts to the Moon by 2020, according to a
draft internal report on delaying the planned 2010 retirement of the orbiter
fleet.
However,
extending shuttle operations to 2015, when a replacement system is slated to
become available, would cost more than $11 billion and have severe impacts on lunar
exploration hardware development, according to the draft report,
prepared by a team at NASA's Johnson Space Center in Houston.
Both
scenarios assume that the additional funding needed to keep the shuttle flying
does not come out of the budgets for developing the replacement system,
consisting of the Orion crew capsule and its shuttle-derived
Ares 1 launcher. Both vehicles are being developed under the Constellation
program, which encompasses the hardware NASA needs to transport astronauts to
and from the International Space Station after the shuttle retires and later to
the moon.
Shuttle extension scrutiny
NASA
Administrator Mike Griffin ordered the study in August amid increased concerns
over the five-year gap between the shuttle's retirement and the debut of Orion
and Ares 1. NASA's plan to rely exclusively on Russian Soyuz vehicles to launch
astronauts during that period came under heavy criticism following Russia's
August invasion of neighboring Georgia.
In a Dec.
15 interview, Griffin called reliance on Soyuz "unfortunate in the
extreme," but said NASA needs the $3 billion it spends annually on shuttle
to move ahead with the replacement system.
"Every
time I have spoken about [the gap] I've laid it at the feet of budget,"
Griffin said. He emphasized that without an increase in NASA's overall budget,
extending shuttle operations will result in a corresponding delay to Orion-Ares
1.
The shuttle
extension study began two months before NASA kicked off another study of
other options for closing the five-year gap. In October, a team from the NASA
Engineering and Safety Center at Langley Research Center in Hampton, Va., began
assessing whether NASA could accelerate development of Ares 1 and Orion. NASA
officials have said Ares 1 and Orion will begin space station missions in March
2015, although they have set an internal deadline of September 2014 and are
under pressure to further reduce the gap.
The
internal assessments will be compared and finalized before being released
sometime in January, Doug Cooke, NASA associate administrator of Exploration
Systems, told reporters during a Dec. 17 teleconference.
"The
study we did on acceleration didn't assume the shuttle extension, so we've got
to get to a resolution on all of that," said Cooke, who declined to
discuss details of a Dec. 15 briefing on the acceleration study. "We need
to understand that all together."
Weighing cost, added risk
The shuttle
draft report, a copy of which was obtained by Space News, evaluates the
implications of the two- and five-year extension scenarios for their costs,
work force implications and impacts on the Constellation program.
According to
the study, both options increase the risk of losing a crew or vehicle: The
two-year extension increases the cumulative risk from a 1-in-8 probability to 1
in 6; extending operations through 2015 increases the risk to 1 in 4. The risk
of losing an orbiter or crew on any given mission is 1 in 77, the report said.
A decision
on whether to pursue either extension option is needed by May 2009 to reverse
plans to draw down shuttle operations, the draft report said.
A two-year
shuttle extension offers limited benefits but does not carry significant
technical risk. It does not eliminate the gap or solve work-force retention
issues, but would benefit the space station and provide an opportunity to use
the shuttle to test Constellation hardware. Examples include Orion's thermal
protection system and docking system, the draft report said. Contract
extensions of up to 24 months would be required for hardware such as the space
shuttle onboard computer, robotics, camera system, reusable solid rocket motor,
main engines and external tanks.
While there
would be no need to produce new shuttle external tanks under the 2012 option,
extending related activities at NASA's Michoud Assembly Facility in New Orleans
could delay modifications of the facility needed to begin producing the Ares 1
upper stage. That, in turn, could delay the start of Ares 1 upper stage
production by 12 months, the draft report said, adding that NASA is developing
mitigation plans.
The launch
manifest under the first option - not counting the November launch of space shuttle
Endeavour - would
include 12 flights during the next four years: four in 2009, four in 2010,
three in 2011 and one in 2012. Space shuttle Discovery would make its final
flight in August 2010 and Atlantis in February 2011.
The
22-launch manifest under the five-year extension option features four missions
in 2009 and three in each of the following six years. Atlantis would be retired
after 2010 and available to provide spares to Discovery and Endeavour.
While
preserving NASA's ability to fly astronauts to the space station until Ares 1
and Orion come on line - albeit
at a cost of $11.4 billion - the five-year shuttle extension would severely impact various other
elements of the Constellation, including the heavy-lift Ares 5 cargo launcher.
Ares
1 and Ares 5 will lift off from a pair of launch pads currently used by the
shuttle. Modifications to Pad A to accommodate the Ares 5 are scheduled to
begin in 2012, but a five-year extension of shuttle operations would delay that
by two to three years unless NASA can find a way to use Pad B both for shuttle
missions and Ares 1 test flights, the report said. The five-year option
also likely would require NASA to move Ares upper stage manufacturing
operations to another facility at Michoud, the report said. The change could
delay Ares 5 by 18 to 25 months.
Other
issues NASA would have to resolve to keep the shuttle flying five more years
include:
- A
15-month to 16-month development delay on the Ares J-2X upper stage
engine, unless NASA can modify its A1 test stand at Stennis Space Center
in Mississippi to accommodate testing of both that engine and the space
shuttle main engine.
- The
availability of North American Rayon, a specialty material used to
manufacture shuttle and Ares solid-rocket motor nozzles, is limited, which
means the capacity to produce Ares vehicles would be drastically reduced.
- Space
shuttle solid rocket booster production would require $23 million in 2009
for skills retention, and the insulating material for the motor would
require a new indemnification agreement or qualification of a replacement
material, as production is scheduled to end in 2010.
- Orion's
space station rendezvous and docking system would have to be altered to
allow it to dock at a different location so the shuttle can continue to
use its primary docking port.
- NASA
would have to recertify vendors soon to enable extended operations.
The 2015
option assumes that the space shuttle will cease operations as soon as a
replacement becomes available, be it Orion-Ares 1 or a commercially developed
alternative.
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