Excessive Rocket Vibration, Another Problem, May Be Resolved With Design Changes
The Constellation Program to develop the next-generation Orion-Ares spaceship faces multiple risks of technology development problems, schedule delays and cost overruns, according to the non-partisan Government Accountability Office (GAO), the federal watchdog agency.
Excessive thrust oscillation vibration caused by the Ares rocket, a history of weight problems in both the Orion capsule and the rocket, the lack of experience in building the protective heat shield for the Orion crew exploration vehicle space capsule, and more confront program executives, according to the GAO report.
However, NASA officials said the vibration problem may be resolved by “tuning” the rocket structure to lessen vibration, using shock absorbers to damp the vibration reaching the astronaut crew in the capsule, and other steps. Otherwise, the crew could be injured by the intense vibration during the climb to orbit.
The GAO report was presented before the House Science and Technology Committee space and aeronautics subcommittee by Christina T. Chapman, director of GAO acquisition and sourcing management.
As NASA approaches the Orion-Ares preliminary design review this year, GAO is concerned that “there are considerable unknowns as to whether NASA’s plans for these vehicles can be executed within schedule goals and what these efforts will ultimately cost. This is primarily because NASA is still in the process of defining many performance requirements.”
These are major issues, according to GAO. “Such uncertainties could affect the mass, loads, and weight requirements for the vehicles. NASA is aiming to complete this process in 2008, but it will be challenged to do so given the level of knowledge that still needs to be attained. The challenges NASA is facing pose risks to the successful outcome of the projects.”
Lockheed Martin Corp. [LMT] leads companies developing Orion, while various sections of the Ares rocket are being developed by The Boeing Co. [BA], ATK, Pratt & Whitney Rocketdyne (a United Technologies Corp. [UTX] unit), and others.
These are some of the potential snafus in the Orion astronauts’ space capsule and Ares rocket programs, according to GAO:
- Both vehicles have a history of weight issues.
- That excessive vibration during launch threatens system design.
- There is uncertainty about how flight characteristics will be impacted by a fifth segment added to the Ares I launch vehicle.
- The Ares I upper stage essentially requires development of a new engine.
- No industry capability currently exists for producing the kind of heat shields that the Orion will need for protecting the crew exploration vehicle when it reenters Earth’s atmosphere.
- Existing test facilities are insufficient for testing Ares I’s new engine, for replicating the engine’s vibration and acoustic environment, and for testing the thermal protection system for the Orion vehicle.
That, according to the GAO, is a lot that can go wrong.
“All these unknowns, as well as others, leave NASA in the position of being unable to provide firm cost estimates for the projects at this point,” according to the watchdog agency. “Meanwhile, tight deadlines are putting additional pressure on both the Ares I and Orion projects. Future requirements changes raise risks that both projects could experience cost and schedule problems.”
But all of this doesn’t mean disaster is unavoidable, according to the GAO.
“GAO’s past work on space systems acquisition and the practices of leading developers identifies best practices that can provide decision makers with insight into the progress of development at key junctures, facilitate congressional oversight, and support informed decision making,” according to the report.
“This work has also identified common red flags throughout development, which decision makers need to keep in mind when assessing the projects,” the report explained.
For example, weight growth is often among the highest drivers of cost growth. Unanticipated software complexity, often indicated by increases in the number of lines of code, can portend cost and schedule growth.
As well, key junctures in a program can reveal emerging problems. The preliminary design review, critical design review, and production review are key junctures that involve numerous steps and help focus the agency on realistic accomplishments within reachable goals. A disciplined approach aligned with key indicators can provide the knowledge needed to make informed investment decisions at each review, according to the GAO.
The full report and testimony titled “NASA: Ares I and Orion Project Risk and Key Indicators To Measure Progress” can be read in full at http://www.gao.gov on the Web, under report GAO-08-186T.