NASA announced that the Space Launch System (SLS) passed a critical milestone yesterday that moves the massive rocket a step closer towards reality. But buried within the announcement was news that the SLS’s inaugural launch date could slip by nearly a year to November of 2018.
The milestone has the delightfully obtuse name of Key Decision Point C (KDP-C). NASA missions are broken down into project phases A through F, each representing a different point and set of challenges in the lifecycle of the program. Phase A, for example, is primarily focused on basic concept and technology development. Phase E, on the other hand, is the actual operations part of a mission. The Curiosity rover is in Phase E as we write this.
Phase C, as you might imagine, sits squarely in the middle of these two extremes. But it’s important, as it represents a major shift in the project, and KDP-C is the gateway for this shift. As of now, the SLS has moved on from design and development into actual physical implementation. Fine-grained schematics can now be developed for all systems and subsystems. The components that make up these systems are being built or bought. No more major design changes can happen from this point on without major costs and delays.
To pass into Phase C-land, the SLS had to make it through two major reviews: a technical assessment and a programmatic assessment.
The technical assessment looked at the vehicle’s design to make sure it can actually fly, a rather important capability for a rocket. Robert Lightfoot, NASA’s associate administrator, said the vehicle passed its technical assessment with flying colors. “There were absolutely no issues with the great progress that the team has made, and they were cleared to proceed to the critical design review,” he said. The Critical Design Review (CDR) is another technical test the SLS will face midway through Phase C, where a group of experts reviews the detailed design drawings and test plans.
The second component of KDP-C was the programmatic assessment. Here, NASA took cost and scheduling estimates for the project and fed them into modeling software. The modeling software spits out an industry standard number called a Joint Confidence Level (JCL). Government Accountability Office and NASA standards call for a JCL of 70% or higher for most projects to remain healthy. JCLs have been successfully used on NASA science missions, but this is the first time they have been used on a human spaceflight program.
Basically, the JCL calculates the likelihood you’ll deliver an on-time and on-budget project under various cost and schedule scenarios. Do you want an aggressive timeline and a high level of confidence that you will achieve it? You’ll need to increase the money available to the program to be able to throw resources at unexpected problems. Don't have extra money? The JCL will tell you that you'll need to delay your goals instead. This confidence level helps managers get a grasp on what financial/time cushion is needed to complete a project.
The problem is that the SLS’s budget has been and will remain relatively flat. Engineering projects usually have a curve of funding that peaks during the construction phase of the mission, since this is when workforce needs are the highest. This is also the phase when most technical and engineering problems crop up. The SLS doesn’t have the luxury of a proper funding profile within NASA’s already strained budget, so there’s little room for an extra financial cushion.
So essentially, to get a JCL of 70% with a White House-proposed budget of $7 billion from February 2014, the modeling software told NASA they should be prepared for the December 2017 launch date to slip to November 2018. William Gerstenmaier, NASA’s associate administrator for the Human Exploration and Operations Mission Directorate, hopes to beat that November 2018 estimate, and said his teams are continuing to operate on their original schedules. The original 2017 launch date can happen if nothing goes wrong. But the whole point of the JCL is that it assumes something will go wrong—it always does.
The exact reasons the programmatic assessment decided the December 2017 launch date wasn’t feasible isn’t clear, but we do know that it’s not related to the Orion crew capsule. “[The JCL assessment] includes just the development activities associated with building the rocket,” Gerstenmaier said, adding that a KDP-C analysis for SLS ground systems is expected next. Orion will also face a KDP-C sometime after its inaugural test flight.
NASA currently has official plans for three flights of Orion—the latter two of which take place with SLS. The first launch happens this December on top of a Delta IV Heavy rocket and is uncrewed. Orion next flies on the debut launch of SLS, which now has the “no later than” date of November 2018. This mission will also be without a crew.
The SLS will then launch the first crewed mission sometime around 2021. Gerstenmaier said that if the agency’s Asteroid Redirect Mission has delivered an asteroid to lunar orbit by then, this mission will visit the asteroid. If not, it will still send humans to orbit the moon, but serve as a test flight. Current budget plans do not include anything beyond this for either the SLS or Orion.