The National Aeronautics and Space Administration Authorization Act of 2010 directed NASA to, among another things, develop a Space Launch System as a follow-on to the Space Shuttle and prepare infrastructure at Kennedy Space Center to enable processing and launch of the Space Launch System as a key component in expanding human presence beyond low-Earth orbit. To fulfill this direction, NASA formally established the SLS program in 2011. The agency plans to develop three progressively more capable SLS launch vehicles, complemented by Orion, to transport humans and cargo into space. The first version of the SLS that NASA is developing is a 70-metric ton (mt) launch vehicle known as Block I. In accordance with direction contained in the NASA Authorization Act of 2010, NASA’s acquisition approach for building the initial variant of the SLS is predicated on the use of legacy systems, designs, and contracts from the Space Shuttle and its intended successor Constellation program, which was terminated in 2010 due to factors that included cost and schedule growth. Figure 1 provides details about the heritage of each SLS hardware element and its source as well as identifying the major portions of the Orion crew vehicle. NASA plans to use heritage hardware and new designs as follows: RS-25 engines remaining from the Space Shuttle program to provide power for up to four flights of the SLS, five-segment solid rocket boosters that were developed under the now-canceled Constellation program to provide thrust during the initial minutes of SLS flight, a cryogenic rocket stage used on United Launch Alliance’s Delta IV launch vehicle modified to operate as the Interim Cryogenic Propulsion Stage (ICPS) to provide in-space power for SLS during EM-1, a new core stage, which functions as the SLS’s fuel tank and structural backbone, derived from the Shuttle’s external tank and Ares I upper stage from the Constellation program, a new launch vehicle stage adaptor to attach and integrate the ICPS to the core stage; and a new multi-purpose crew vehicle stage adaptor to attach and integrate the SLS with the Orion vehicle. NASA has committed to be ready to conduct one test flight, EM-1, of the Block I vehicle no later than November 2018. During EM-1, the Block I vehicle is scheduled to launch an uncrewed Orion to a distant orbit some 70,000 kilometers beyond the moon. All three programs—SLS, Orion, and EGS—must be ready on or before this launch readiness date to support this test flight. NASA also intends to build 105- and 130-mt launch vehicles, known respectively as Block IB and Block II, which it expects to use as the backbone of manned spaceflight for decades. NASA anticipates using the Block IB vehicles for destinations such as near-Earth asteroids and Lagrange points and the Block II vehicles for eventual Mars missions. When complete, the 130-mt vehicle is expected to have more launch capability than the Saturn V vehicle, which was used for Apollo missions, and be significantly more capable than any recent or current launch vehicle. To enable processing and launch of the SLS and Orion, NASA established the Ground Systems Development and Operations program in 2012 at Kennedy Space Center. The Ground Systems Development and Operations program consists of the 21st Century Space Launch Complex Initiative and the EGS program. NASA created the 21st Century Space Launch Complex Initiative prior to the establishment of the SLS and Orion programs as a way for Kennedy Space Center to continue to make infrastructure improvements to benefit multiple users in the absence of an ongoing major human exploration program. The EGS program was established to renovate parts of Kennedy Space Center to prepare for SLS and Orion. The program consists of nine major components: the Vehicle Assembly Building, Mobile Launcher, Software, Launch Pad 39B, Crawler-Transporter, Launch Equipment Test Facility, Spacecraft Offline Processing, Launch Vehicle Offline Processing, and Landing and Recovery. See figure 2 for pictures of the Mobile Launcher, Vehicle Assembly Building, Launch Pad 39B, and Crawler-Transporter, and appendix III for a description of the nine EGS components. As the SLS and Orion programs began development, NASA shifted focus away from the 21st Century Space Launch Complex Initiative to the EGS program. For example, in fiscal year 2011, Congress appropriated NASA $142.8 million for the 21st Century Space Launch Complex Initiative and this declined to $39 million in fiscal year 2013, which was a year after EGS began receiving funding. Further, in the fiscal year 2017 president’s budget request, NASA requested $12 million to support the 21st Century Space Launch Complex Initiative. Space launch vehicle development efforts are high risk from technical and programmatic perspectives. The technical risk is inherent for a variety of reasons, including the environment in which launch vehicles operate, complexity of technologies and designs, and limited room for error in the fabrication and integration process. Managing the development process is complex for reasons that go well beyond technology and design. For instance, at the strategic level, because launch vehicle programs can span many years and be very costly, programs can face difficulties securing and sustaining funding commitments and support. At the program level, if the lines of communication between engineers, managers, and senior leaders are not clear, risks that pose significant threats could go unrecognized and unmitigated. If there are pressures to deliver a capability within a short period of time, programs may be incentivized to overlap development and production activities or delete tests, which could result in late discovery of significant technical problems that require more money and ultimately much more time to address. For these reasons, it is imperative that launch vehicle development efforts adopt disciplined practices and lessons learned from past programs. Best practices for acquisition programs indicate that establishing baselines that match cost and schedule resources to requirements and rationally balancing cost, schedule, and performance are key steps in establishing a successful acquisition program. Our work has also shown that validating this match before committing resources to development helps to mitigate the risks inherent in complex acquisition programs such as SLS and EGS. We have reported that within NASA’s acquisition life cycle, resources should be matched to requirements at key decision point (KDP)-C, the review that commits the program to formal cost and schedule baselines and marks the transition from the formulation phase into the implementation phase. Best practices for acquisition programs also indicate that about midway through development, the product’s design should be stable and demonstrate that it is capable of meeting performance requirements. The critical design review is the vehicle for making this determination. These programmatic milestones are called out relative to NASA’s acquisition life-cycle in figure 3 below. NASA approved EM-1 cost and schedule baselines for the SLS program in August 2014 and the EGS program in September 2014, following the completion of each program’s respective KDP-C review. The agency baseline commitment for the SLS program is at the 70 percent confidence level and the agency baseline commitment for the EGS program is at the 80 percent confidence level, which are both in line with NASA’s acquisition policies (see table 1). The confidence level is a probabilistic analysis that provides assurance to stakeholders that programs will meet cost and schedule targets. In addition to the committed cost and launch readiness dates, both programs are working towards internal goals of earlier launch readiness dates and lower costs. NASA considers the time between the programs’ internal goals and their committed launch readiness dates as funded schedule reserve, which is extra time, with the money to pay for it, in the program’s overall schedule in the event that there are delays or unforeseen problems. In July 2015, we found that the SLS program’s internal goal for launch readiness for EM-1 had slipped from December 2017 to July 2018. This reduced the program’s schedule reserve from eleven months to four months. In May 2016, the SLS program further delayed its internal goal for launch readiness from July 2018 to September 2018, reducing program schedule reserve to two months. EGS’s internal goal for launch readiness for EM-1 is September 2018, meaning the program currently has two months of funded schedule reserve. The SLS program has made solid progress in resolving some technical issues and maturing the SLS design, but the program’s management of known risks as well as the program’s upcoming integration and test phase puts pressure on the program’s reduced cost and schedule reserves. This pressure threatens the program’s committed November 2018 launch readiness goal. The SLS program has made progress in resolving some technical issues that we previously reported on. For example, prime contractor officials for the core stage stated that they had implemented all corrective actions necessary to repair a problem with the stage’s tooling. Further, the program met its design goals by demonstrating the program’s design was stable enough to warrant continuation. As the program continues with final design and fabrication, the program faces known risks. Such risks are not unusual for large-scale programs, especially human exploration programs, but the program’s management of these risks may increase pressure on reduced cost and schedule reserves. For example, the SLS program has not positioned itself well to provide accurate assessments of progress with the core stage—including forecasting impending schedule delays, cost overruns, and estimates of anticipated costs at completion—because, at the time of our review, NASA did not have a performance measurement baseline necessary to support full earned value management reporting on the core stage contract. Finally, unforeseen technical challenges are likely to arise once the program reaches its next phase, final integration for SLS and integration of SLS with its related Orion and EGS human spaceflight programs that will likely place further pressure on cost and schedule reserves. The SLS program has made solid technical progress developing its primary elements, but at times, the progress has had associated cost increases or schedule delays.