LAS VEGAS — House appropriators want NASA to examine alternatives to a new upper stage for the Space Launch System despite an uncertain long-term future for the vehicle.
The full House Appropriations Committee was scheduled to mark up its commerce, justice and science (CJS) spending bill July 24. However, the committee canceled the markup late July 23 after House leadership elected to begin its summer recess early. The committee, though, did release the report accompanying the bill, which the CJS committee approved July 15.
The report includes language calling on NASA to consider alternatives to the Exploration Upper Stage (EUS), a more powerful upper stage that NASA plans to introduce with the Block 1B version of the SLS on Artemis 4. That larger upper stage, replacing the current Interim Cryogenic Propulsion Stage, will be able to send payloads of up to 38 metric tons on trajectories to the moon, about 10 metric tons more than the current Block 1 SLS.
“The Committee directs NASA to evaluate alternatives to the current Exploration Upper Stage (EUS) design for SLS, with a focus on reducing development and production costs, shortening the schedule, and maintaining the required lift capability of at least 130 tons to low-Earth orbit,” the report states. That payload capacity is a long-term goal for a future Block 2 version of SLS.
“NASA is directed to assess various propulsion systems, stage configurations, infrastructure compatibility, commercial and international collaboration opportunities, and the cost and schedule impacts of each alternative,” the report states, with the report due 180 days after enactment of the bill.
The report doesn’t elaborate on the committee’s interest in alternatives to EUS. An annual assessment of major NASA projects by the Government Accountability Office, published July 1, concluded that work on the SLS Block 1B, which includes EUS, remains on cost and schedule baselines set in late 2023, with a first launch in September 2028 and a total cost of $4.9 billion. The report noted “difficulties manufacturing both the EUS and core stage” for Artemis 4, which it blamed in part on delays for vehicles for earlier flights and delays in receiving parts and materials.
The future of EUS was in doubt when the administration released its fiscal year 2026 budget request, which called for ending SLS with Artemis 3. However, a budget reconciliation bill enacted earlier this month included $4.1 billion to produce SLS vehicles for Artemis 4 and 5.
The House report supports continued development of SLS and Orion, directing NASA to continue procuring hardware “to support a sustained annual flight cadence of the SLS and Orion spacecraft.” It rejects proposals to use commercial alternatives until such a vehicle, capable of sending at least 42 metric tons to the moon, is successfully demonstrated.
Science, technology and space operations
The bill and report provide $24.838 billion for NASA overall in fiscal year 2026, slightly less than 2025 funding levels of $24.875 billion. That includes exactly $6 billion for science, less than the $7.33 billion in 2025 but significantly higher than the $3.9 billion requested by the administration for 2026.
The science funding includes $300 million for Mars Sample Return (MSR), which the NASA request proposed to cancel and a companion Senate bill was silent on. The House report cited the priority Mars Sample Return had in decadal surveys, Chinese plans for a Mars sample return mission late this decade and technologies developed for MSR that could be used for future human missions.
The report directed NASA’s Science Mission Directorate work with the Exploration Systems Development Mission Directorate (ESDMD) on MSR technologies that could be applicable on future exploration, and also calls for an assessment of potential commercial partnerships for MSR.
The report also allocates funding for several missions facing cutbacks or cancellations, from the OSIRIS-APEX mission en route to the asteroid Apophis to the Laser Interferometer Space Antenna mission NASA is cooperating with ESA on. It includes $376.5 million for the Nancy Grace Roman Space Telescope to keep that mission on schedule for a launch as soon as the fall of 2026.
In space technology, the House report rejects proposals to cancel work on nuclear propulsion. The report includes $80 million for development of nuclear electric propulsion and $175 million for nuclear thermal propulsion, with work on that latter system to be transferred from the Space Technology Mission Directorate to the Mars Campaign Office within ESDMD.
In space operations, the report includes $500 million for Commercial LEO Development, far more than the $272.3 million requested. The report directs NASA to accelerate procurement for the next phase of the program, completing that work within 90 days of the bill’s enactment.
The report includes $5 million for “modification and certification activities” for commercial cargo spacecraft supporting the International Space Station to allow such a spacecraft to provide an emergency crew return capability. That capability, the report notes, would allow the converted vehicle “to safely reenter and land crew on a runway within the continental U.S.”
Such a provision would appear to be intended for Sierra Space’s Dream Chaser, the only cargo vehicle with a NASA resupply contract capable of a runway landing. Sierra Space has outlined plans to create a crewed version of Dream Chaser, but that schedule is uncertain. The first cargo flight of Dream Chaser has experienced extensive delays and is now unlikely before late this year.