NASA Exploration Systems Mission Directorate Responses to Questions from NASA Watch Feb. 20, 2008

Q: Has NASA directed civil servants and/or contractor personnel to look at Orion CEV designs that would be limited flying a crew of 4 to the ISS?

A: No.

Q: Has NASA directed civil servants and/or contractor personnel to look at Orion CEV designs that would be limited flying a crew of less than 6 to the ISS?

A: No.

Q: As part of these design studies has the possibility of reducing the final permanent crew complement of the ISS to 4 been discussed?

A: No.

Q: Has NASA directed civil servants and/or contractor personnel to look at proposals to eliminate some protuberances (some inactive) on Ares I-X that will simulate those that will be on the final (operational) Ares I CLV? If so what is the reason for eliminating these protuberances? Cost? Performance?

A: NASA established the Ares I-X outer mold line in mid-2006, with the understanding that the final Orion-Ares outer mold line could change. Ares I-X is designed to be similar to Ares I so that engineers can obtain flight data to validate and anchor Ares I computer models. However, the outer mold line will not affect any primary or secondary mission objectives.

Ideally, a rocket’s surface would be completely smooth to maximize aerodynamic efficiency. In reality, this is not possible because of certain necessary items such as small thrusters, cable runs and fluid lines. Some of these items, such as the service duct between the Orion command and service modules, have been simulated on Ares I-X to make that rocket resemble Ares I.

Because budgets through fiscal 2010 are tight, Constellation Program Manager Jeff Hanley has asked the Ares I-X team to look at ways to reduce costs and schedule risk. In turn, Ares I-X Mission Manager Bob Ess has asked Ares to review the Ares I-X outer mold line and the potential importance of simulated hardware — such as small thrusters, cable runs and fluid lines — to the test objectives. That assessment continues. If these items are found to be of minimal value in understanding the rocket’s flying qualities, the program may choose to eliminate them.

Q: Has NASA directed civil servants and/or contractor personnel to consider cuts in the amount flight instrumentation that will be placed onto the Ares I-X? If so what instrumentation is being considered for elimination? How will the full set of flight data be obtained from the Ares I-X flight i.e. the original purpose for the Ares I-X flight? What is the reason for eliminating this instrumentation? Cost? Performance?

A: The Ares I-X mission has all the instrumentation it needs to support the primary and secondary mission objectives, which were set in early 2007. All engineering data that will be obtained has been mapped back to these objectives. No compromises have been made in obtaining measurements associated with primary objectives. Some instrumentation proposed for secondary and tertiary mission objectives would have exceeded the avionics system’s ability to process, downlink and store data. Therefore, the design incorporates data points that will satisfy all secondary objectives. Other measurements of opportunity have been incorporated where possible.

Some locations on the vehicle are more difficult to instrument, and this fact can affect schedules. Two such areas of concern are the aft skirt and the upper stage simulator, where engineers have requested some post-separation data. Ares I-X Mission Manager Bob Ess has asked Ares to weigh the importance of these measurements to the test objectives. Such a request is a normal part of the critical design review, the process in which implementation plans for the detailed design are evaluated. If the aft skirt and upper stage simulator post-separation data are found to be crucial to the test objectives, the program will keep the instrumentation.

For data recovery, NASA will use downlink telemetry as well as digital recorders onboard the first stage.

Q: Has NASA directed civil servants and/or contractor personnel to look at how restructuring or replanning of the Ares program may affect Ares if exploration priorities shift away from the Moon to destinations such asteroid visits? If so what changes will need to be made to the Ares 1 and Ares V launch vehicles?

A: No.

Q: Has NASA directed civil servants and/or contractor personnel to look at increasing the size of the Ares V payload shroud from 8.4 meters to 10 meters? If so what is the rationale for this change? Cost? Performance?

A: The Constellation Program baseline was updated in fall 2007 to increase the Ares V shroud diameter and the Earth departure stage diameter to 10 meters. The purpose of this change was to maximize the rocket’s payload capacity and improve the shroud’s ability to accommodate a variety of configurations for the Altair lunar lander, which is still in conceptual development.

Q: Has NASA directed civil servants and/or contractor personnel to look at increasing the 66.9 metric ton TLI payload for the Ares V to 75 metric tons? If so, what is the rationale for this change? Cost? Performance?

A: Ares V configurations in the range described in your question are being traded, as well as refinements to the modeling of mass margins, all of which is under trade study at this time. No decisions have been made on any Ares V performance improvements beyond those adopted in the fall 2007 baseline update of the Constellation Program architecture.