A cash crunch expected to hit in 2009 has NASA considering delaying a key early test
of its Ares 1 crew launch vehicle by as much as a year.
A Jan. 16 memorandum from the head of NASA’s Constellation program, Jeff Hanley, to more than 80 agency officials including NASA field center directors, laid out a new
schedule that delays the launch of Ares 1-Y – the first test flight of the vehicle’s five-segment solid-rocket booster – a full year to September 2013.
Under the revised schedule, which Hanley formally rescinded two days later, the Ares 1’s first launch of an unmanned Orion Crew Exploration Vehicle would be delayed nine months to December 2013, resulting in a six-month delay of the first crewed test flight to March 2014.
Speaking at the Space Transportation Association (STA) breakfast here Jan. 22, NASA Administrator Mike Griffin said Hanley had “screwed up” by announcing a new flight test schedule without first consulting with NASA headquarters. However, Griffin also said the test schedule was likely to slip.
“We probably will be making changes in our intermediate milestones in order to best preserve with maximum confidence the end date for the availability of Ares and Orion,” Griffin said.
Hanley’s schedule memo, which leaked to the
Web sites NASAWatch.com and NASAspaceflight.com, kept intact the plan to conduct
Orion’s first flight to the international space station
September 2014. That is the more aggressive, internal date the Constellation program has been working toward to better ensure that NASA can meet its public commitment to field the new system by March 2015.
Hanley, who was in Washington to attend Griffin’s STA breakfast speech
, told reporters afterwards that the proposed schedule change was driven by a roughly $700 million shortfall the Constellation program anticipates between 2008 and 2010.
Hanley said the program’s cash crunch is most severe in 2009, the year it would need to place its order for the Ares 1-Y booster to allow the standard three-years lead time for 2012 test launch.
Hanley acknowledged that compressing the test schedule for Ares and Orion
would introduce additional schedule risk, but said it was “not unreasonable” to plan on conducting three separate Orion flight tests in the space of six months – half the time allotted under the present schedule.
Budget matters and schedule slips are not the only thorny issues facing NASA’s Constellation program. Engineers also have been wrestling for months with a potentially dangerous vibration issue discovered during computer flight simulations of Ares and Orion.
Taking questions after his speech, Griffin downplayed the design issue that surfaced during those simulations as “an interesting engineering problem” with numerous possible solutions. He also stressed
ultimately might discover that Ares does not really have a
vibration problem that needs to be addressed.
Griffin said the
worrisome vibrations showed up during computer simulations of the launch of the Ares 1 rocket and the Orion Crew Exploration Vehicle. However, as has happened in similar cases in the past, a more in-depth analysis could reveal the vibration problem to be a non-issue from a safety standpoint, Griffin said.
Griffin said the modeling and simulations that brought the vibration issue – what engineers call thrust oscillation – to the attention of Constellation officials were based in part on flight data collected many years ago when the solid-rocket boosters NASA uses to launch the space shuttle were still in development.
Griffin also said NASA has altered the design of Orion since running the simulations that produced the troubling vibration results. “We are not even certain we have a problem,” he added.
NASA and its contractors have been working since 2005 to design and build Ares 1, an expendable rocket that will use a taller, more powerful version of the space shuttle solid-rocket booster and a liquid-fueled second stage to boost the Orion capsule into orbit.
The Associated Press and the Web site NASAWatch.com reported Jan. 18 that NASA engineers were worried Ares and Orion could be shaken apart during launch as vibrations originating in the rocket’s first stage are amplified as they travel up the stack.
Griffin expressed surprise that the issue
had garnered so much attention over the weekend prior to his speech, with hundreds of media outlets picking up the AP story. “I have rarely seen more of a mountain made out of less of a mole hill,” he said.
Griffin said the thrust oscillation phenomenon is common to solid rockets, the outer cases of which tend to resonate “like an organ pipe” as their rubber-like propellant burns from the inside out during flight. He said engineers have encountered and dealt with similar vibration problems during the development of multiple launch vehicles, including the Minuteman ballistic missile and the Titan family of rockets.
“In the case of the early Minuteman, it was severe and in fact they ended up modifying the internal flow dynamics of the motor grain to solve it, which in fact is one of the solutions we are looking at,” Griffin said.
NASA also can “tune” the rocket in various ways to ensure that vibrations originating in the main stage are not amplified as they travel up the stack. Another possible solution, should further testing and analysis show the problem to be real, would be to isolate
the Ares payload from
the vibrations by, for example, placing rubber pads between Orion and the second stage.
“We have several solutions. We’re working them. We’re taking it seriously,” Griffin said.