Bill Gerstenmaier, the head of NASA’s human spaceflight program, expressed confidence that NASA will meet Vice President Mike Pence’s goal of putting humans aboard the lunar-orbiting Gateway, which is still in development, by 2024. Most of the presentations at the meeting of a NASA advisory committee Monday shied away from specific dates, but he projected certainty on this point even though some committee members were skeptical. The meeting continues today (Tuesday) with a focus on science and exploration missions in “cis-lunar” space on and around the Moon.

NASA continues to update its human exploration timelines in the wake of the Trump Administration’s decision to restore human lunar landings to the plan.

In the latter years of the Obama Administration, the agency laid out the sequence of “Exploration Missions” through the end of the 2020s. Little of that is relevant today, but Exploration Mission-1 (EM-1) remains an uncrewed test flight of the Space Launch System (SLS) and Orion spacecraft. EM-2 remains the first crewed flight and EM-3 will take astronauts to the Gateway.

The Gateway (formerly the Deep Space Gateway or Lunar Orbital Platform-Gateway) will be in lunar orbit and is envisioned as a transfer point for crews travelling to the lunar surface or into deep space. Initially it will consist of a Power and Propulsion Element (PPE), a habitation module, and an airlock, with crews coming and going via Orion spacecraft.

Last week, Vice President Pence asserted that Americans would be aboard the Gateway “before the end of 2024” (the last year of a Trump second term if he is reelected). At Monday’s meeting of the NASA Advisory Council’s Human Exploration and Operations (HEO) committee, Gerstenmaier and other top NASA officials laid out their near-term human exploration plans, which include launching the PPE in 2022. Gerstenmaier said humans can be on the Gateway as soon as EM-3 arrives in 2024.

Some committee members were skeptical that PPE will be ready by 2022, and therefore the Gateway by 2024. NASA is acquiring the PPE through a public-private partnership and it will be launched by a commercial rocket, not SLS. Michele Gates, NASA’s director for the PPE, said she expects the contract to be awarded in March 2019 and PPE ready for launch by 2022. Skeptics found that to be a very aggressive schedule, but she and Gerstenmaier stressed that PPE will be built on an existing communications satellite “bus” design augmented with a high power solar electric propulsion system (SEP). The communications satellite industry is mature and routinely builds satellites in 24-36 months, they insisted, so they consider the schedule achievable.

The evolution of the Gateway is a work in progress. Gerstenmaier presented this rather complex graphic to illustrate how NASA currently envisions it.

Monday’s briefings did not clarify the current expected launch date for the uncrewed EM-1 test flight (notionally it is 2020), but Bill Hill, who leads NASA’s exploration systems development, said EM-2 will launch in mid-2022. It is the crewed SLS/Orion test flight.

NASA is replanning EM-2 now that it will use a less capable upper stage. Earlier this year, Congress suddenly added money to NASA’s budget to build a second Mobile Launcher. That means there will be one for SLS with its Interim Cryogenic Propulsion Stage (ICPS) and the other for SLS with its more powerful Exploration Upper Stage (EUS) and there can be parallel flights of the two versions. Originally only EM-1 was to use the ICPS followed by a 33-month hiatus to retrofit the first Mobile Launcher to accommodate the larger EUS. That is no longer an issue. Now EM-1, EM-2, and possibly the robotic mission to Jupiter’s moon Europa will use ICPS. Hill showed this graphic of the new EM-2 mission, which will still meets the requirements for a crewed flight test.

The current plan, then, is for three SLS/Orion launches — in 2020 (EM-1), 2022 (EM-2), and 2024 (EM-3) — plus another possible SLS launch of the robotic Europa probe in the 2022-2023 time period. All but EM-3 will use ICPS.

What comes after EM-3 is vague. Gerstenmaier presented this graphic of the “path” to the lunar surface. It provides no date for when humans will land, but judging by the illustration on the far right of the slide, it will be well after 2026.

In the nearer term, though, the focus clearly will be on getting humans on the Gateway by 2024.

The NAC HEO committee will continue its meeting today (Tuesday) in a joint session with the NAC Science Committee. Science and exploration activities on and around the Moon — in cis-lunar space — will be the focus.