Orion Enters Fabrication Phase, but Possible Launch Slip Looms
Posted by Jason Davis
16-09-2015 15:03 CDT
NASA's Orion spacecraft has officially moved from preliminary design to fabrication, but the agency says the first crewed flight of the vehicle could slip two years, from 2021 to 2023.
During a Wednesday call with reporters, NASA officials said the capsule cleared a milestone known as Key Decision Point C, or KDP-C. This marks the completion of the program's preliminary design phase, and sets cost and schedule restraints moving forward. From the start of fiscal year 2016 in October 2015 through the vehicle's inaugural crewed flight, Orion's budget has been set at $6.77 billion.
Until now, that first astronaut-carrying flight, Exploration Mission 2—a sojourn to lunar orbit—was expected to occur in 2021. It will be preceded by EM-1, a similar but uncrewed trip to the moon scheduled for late 2018. EM-1 will also mark the debut of the Space Launch System.
During KDP-C, NASA used an analysis known as the Joint Confidence Level, or JCL, to find a target launch date for EM-2 that has at least a 70 percent probability of being met, given required workloads and budget numbers. A longer lead time, more money or both can increase the confidence level. To get to 70 percent, officials set a "no later than" date of April 2023 for EM-2—a potential two-year slip.
Despite the analysis, NASA associate administrator Robert Lightfoot saw no reason to change his team's internal 2021 deadline.
"I've asked the team to continue working toward their original August 2021 date," he said. "That's where their planning is today—they're planning and working toward that date, recognizing that we have a much lower confidence in that date."
William Gerstenmaier, NASA's associate administrator for Human Exploration and Operations, agreed.
"I think we're being somewhat conservative," Gerstenmaier said. "But if you look at the complexity of what we're doing in building this spacecraft, there will be some unknowns that show up, and to protect from those, we went with the later date."
The first crewed Orion mission will be the vehicle's third flight. In December 2014, it launched atop a United Launch Alliance Delta IV Heavy rocket that sent the capsule on a two-orbit shakedown cruise. The precise date of EM-1, the second flight, will be set after Orion, the Space Launch System and NASA's ground systems division all complete their Critical Design Reviews. SLS teams recently completed their CDR, and the results are being reviewed by NASA.
"There's nothing right now to indicate that we can't meet the Fall 2018 date for EM-1," Lightfoot said.
With the clearing of KDP-C, NASA puts a price tag on a program that has, until now, had a dynamic cost. In the agency's fiscal year 2016 budget request, the cost of Orion was pegged between $8.5 and $10.3 billion. This does not include previous work under the canceled Constellation program.
Lightfoot and Gerstenmaier laid out a variety of reasons Orion could not commit to a 2021 launch date. These included equipment reusability problems between Orion flights, completion of a structural test article, software development, and the delivery timeline for the capsule's service module. The service module, which houses the vehicle's main engine, as well as consumables like fuel and water, is being built by the European Space Agency.
Additional delays have been caused by what Gerstenmaier termed "unknown unknowns," which remain a source of concern moving forward. One such problem involved an action initially meant to save weight and reduce construction complexity.
"One thing we did was make some changes to reduce weight. We took a lot of weight out of the structure for EM-1 and EM-2—roughly 500 pounds or so," he said. "We also reduced the number of cone panels that make up the cone section." The cone section sits above Orion's main barrel and marks the point where the vehicle slopes up to the smaller forward bulkhead.
The new panels, Gerstenmaier said, started to warp out of their bent shape. "When we machine the material out to make them lighter, they tend to want to go back to a flat sheet. We didn't recognize that would be a problem."
Despite such snags, Lightfoot said there are no major design problems with the capsule.
"For the technical assessment, there were really no issues with the great progress the team's been making—really nothing to stop them from clearing to proceed to CDR," he said.
The Orion that will fly atop SLS for EM-1 is already coming together at the Michoud Assembly Facility in New Orleans, Louisiana. On Saturday, September 5, engineers welded together the capsule's tunnel and forward bulkhead—the first of seven welds required to assemble the vehicle's primary structure.
Gerstenmaier said that though the flights of EM-1 and EM-2 are important prerequisites needed to prepare the vehicle for operational missions, a delay for one mission does not necessarily mean a delay for the other.
"If we just wanted to launch EM-1 by some date, we could move test requirements off of EM-1 and move them later in the first portion of EM-2, and maybe down-scope EM-2," he said. "And that's not what we want to go do. We want to make sure we get all the right testing done on EM-1, and we can actually move forward with EM-2."
Even if EM-2 slips to 2023, he said, it would not likely be the mission NASA uses as part of the Asteroid Redirect Mission—a crewed visit to a captured asteroid in Earth orbit.
"In general, you would really like to get the vehicle fully checked out and spend some time doing some unique things with the vehicle, and make sure crew interactions with the vehicle really work they way you intended," Gerstenmaier said. "Then when you go to that operational mission like the Asteroid Redirect Mission, where your focus now is to go do an EVA and [de-pressurize] the Orion capsule and go out and grab a sample off the asteroid, you make sure you can really focus on all of those [objectives] first."