The Exploration Upper Stage seems nowhere near readiness. NASA will likely launch its first astronauts into deep space since the Apollo program on a less powerful version of its Space Launch System rocket than originally planned. Although it has not been officially announced, in recent weeks mission planners at the space agency have begun designing "Exploration Mission 2" to be launched on the Block 1 version of the SLS rocket, which has the capability to lift 70 tons to low Earth orbit. On Thursday, during a Congressional hearing, the agency's acting administrator, Robert Lightfoot, confirmed that NASA is seriously considering launching humans to the Moon on the Block 1 SLS. "We'll change the mission profile if we fly humans and we use the Interim Cryogenic Propulsion Stage (ICPS), because we can't do what we could do if we have the Exploration Upper Stage," Lightfoot said. The key difference between the original configuration of the SLS rocket—which NASA has spent more than $10 billion developing since 2011—and its successor is the upper stage that sits atop the booster. Under current plans, the weaker upper stage, known as the ICPS, was to fly only once—on the maiden flight of the SLS rocket in 2020. Then, NASA was to switch to a new, much more powerful second stage that would increase the SLS rocket's overall performance by about 50 percent. However, this decision also suggests the agency remains far from developing the powerful Exploration Upper Stage, which NASA says it needs to carry out an ambitious program of lunar exploration. This may well delay meaningful exploration in and near the Moon into the mid- and late-2020s, at the earliest. Until a couple of weeks ago, NASA didn't have the option of flying crew on an ICPS upper stage. Thanks to Congress, however, the agency can now consider flying the Block 1 version of the SLS rocket multiple times. Last month, as part of the fiscal year 2018 budget deal, Congress appropriated $350 million for a new piece of hardware—a mobile launch tower to be built at Kennedy Space Center in Florida. NASA already has one of these massive towers, which supports the testing and servicing of the SLS rocket, as well as moving it to the launchpad and providing a platform from which it will launch. After the first flight of the SLS rocket, NASA had planned to spend 33 months rebuilding the tower to handle the larger, more powerful version of the SLS with the Exploration Upper Stage. With the additional Congressional funding, it can now start building that second tower and continue to use the existing mobile launch tower for Block 1 SLS launches. Lightfoot said Thursday that the agency was only beginning to process how best to use this Congressional largesse, which had not been sought in the White House budget. "You're going to have to give us a little time — it was just a couple of weeks ago that we found out we were getting that—to be able to understand the flow," Lightfoot said. NASA's consideration of flying the first crewed mission into deep space on an SLS rocket with the ICPS upper-stage buttresses the notion that the space agency is struggling with development of the Exploration Upper Stage. Sources have told Ars that the cost of this program has grown beyond expectations. Originally, this 18-meter-tall stage was to be powered by four RL-10 rocket engines. However, in a solicitation late last year, NASA indicated it was looking for lower-cost engines to power the stage. NASA has issued other solicitations to industry, too, that suggest it is concerned about the cost of the upper stage. During an interview this week, former space shuttle program manager Wayne Hale, who is a member of NASA's Advisory Council, said it will probably take four or five years for development and construction of the Exploration Upper Stage from this point onward. You're building an entirely new rocket, Hale said. "It's not just a tank with some engines bolted onto it. It has to be aerodynamic. It has to be able to take the shock and vibration of launch. It's got to be started pretty much from scratch. So yeah, it's complicated. " Launching at least one crewed mission or more with the basic, Block 1 rocket buys NASA time for development of the new upper stage, without the embarrassment of long gaps between flights of the SLS rocket. But the decision does not come without its challenges, either. No astronauts have ever flown on a rocket with the ICPS, so it would have to undergo a time-consuming and costly process of "human-rating" the hardware. With the ICPS, the flight profile for Exploration Mission 2 would still include a crewed checkout of Orions systems in high-Earth orbit, a lunar flyby, and free return trajectory back to Earth. However, flying this mission on a Block 1 SLS would preclude a co-manifested payload that had been planned. NASA had not yet specified this payload for the first crewed flight, but it could have had a mass of up to nine tons. Without the Exploration Upper Stage, NASA will not be able to fly, in a single flight, crew members and pieces of a deep space gateway it hopes to build near the Moon in the 2020s. Additionally, by continuing to fly the SLS rocket in its Block 1 configuration, NASA opens itself up to the criticism that its own heavy-lift rocket is not that much more powerful than commercial options available now or within a few years. Both SpaceX's Falcon Heavy rocket and Blue Origin's New Glenn have a lift capability of about 50 tons to low Earth orbit. However, they cost only a tiny fraction of what the SLS will require to build and fly.
NASA may make some big changes to the first couple flights of its future deep-space rocket, the Space Launch System, after getting a recent funding boost from Congress to build a new launch platform. When humans fly on the rocket for the first time in the 2020s, they might ride on a less powerful version of the vehicle than NASA had expected. If the changes move forward, it could scale down the first crewed mission into deep space in more than 45 years. The SLS has been in development for the last decade, and when complete, it will be NASAs main rocket for taking astronauts to the Moon and Mars. NASA has long planned to debut the SLS with two crucial test missions. The first flight, called EM-1, will be uncrewed, and it will send the smallest planned version of the rocket on a three-week long trip around the Moon. Three years later, NASA plans to launch a bigger, more powerful version of the rocket around the Moon with a two-person crew — a mission called EM-2. But now, NASA may delay that rocket upgrade and fly the same small version of the SLS for the crewed flight instead. If that happens, NASA would need to come up with a different type of mission for the crew to do since they wont be riding on the more powerful version of the vehicle. If EM-2 flies that way, we would have to change the mission profile because we cant do what we could do if we had the [larger SLS], Robert Lightfoot, NASAs acting administrator, said during a Congressional hearing yesterday. NASA clarified that astronauts would still fly around the Moon on the second flight. However, the rocket would not be able to carry extra science payloads as NASA had originally planned. The primary objective for EM-2 is to demonstrate critical functions with crew aboard, including mission planning, system performance, crew interfaces, and navigation and guidance in deep space, which can be accomplished on a Block 1 SLS, a NASA spokesperson said in a statement to The Verge. Modifying these first flights is only possible now thanks to an unexpected influx of cash that NASA got from the recent 2018 spending bill. The space agency received an extra $350 million to build a second launch platform for the SLS. And its giving NASA more flexibility in how it conducts the first few missions of the rocket. The SLS is designed to take off from a portable launch pad — whats known as a mobile launch platform — down at NASAs Kennedy Space Center in Florida. To prep for the first flight of the rocket, NASA has been upgrading an old platform that it originally built for the cancelled Constellation program — an initiative under President Bush to send humans back to the Moon. The upgrades have taken a while though and cost upwards of $400 million, according to the Planetary Society. Its more money than it took to build the platform in the first place. But NASA had a problem: The agency realized that after all the upgrades were complete, the structure would only be able to support launches of the smallest version of the rocket, whats called Block 1. The larger version of the SLS thats supposed to carry crew — called Block 1B — is much taller and heavier; the platform wouldnt be able to support the new height and weight of the vehicle. That meant the platform would have to go through another round of upgrades once the first uncrewed flight of SLS was complete. NASA faced a scheduling mess. The space agency predicted that upgrading the mobile launch platform again would take at least 33 months, or nearly three years. And during that time, the SLS couldnt fly. The platform would be out of commission, so the rocket would be, too. Plus, any delays in upgrading the platform would further delay the first crewed flight into deep space. Ultimately NASA did not officially request the funds for the extra platform, citing costs. So Congress decided to step in. It gave NASA the cash to build a second mobile launch platform from scratch — one that would support the bigger Block 1B version of the rocket. If the space agency starts building the platform now, it could be ready before the planned 2023 launch date for the crewed flight. And NASA wouldnt have to wait for the upgrades to be done to launch a second time. Now that NASA has this cash, the agency is getting creative. It will have two platforms — one for the smaller SLS and one for the bigger version of the rocket. That means NASA can continue launching the smaller Block 1 vehicle until the bigger Block 1B SLS is ready. And NASA is jumping on that option, because it may be a while before the Block 1B can fly. That version of the SLS requires a big, critical piece of hardware known as the Exploration Upper Stage, which sits on the top of the rocket. Its what will give the SLS its extra boost of power, but its a complicated piece of machinery that NASA has never built before. And NASA has already run into many scheduling delays with readying the SLS — a consequence of creating a new vehicle from scratch. So, flying crew on the smaller version of SLS could decrease the time between the first two missions, something Lightfoot admitted to in the hearing. Now knowing were going to build the second mobile launcher, I can keep this mobile launcher in place, buy another [Block 1] and still fly, he said. But that means a crewed mission on Block 1 wont carry any additional payloads — just crew. Lightfoot says the mission will still be enough to certify the SLS for human missions, though. That still gets humans into orbit and that still allows us to check out all the systems we wouldnt check out on EM-1, he said at the hearing. Meanwhile, its also possible that the second flight of the SLS wont carry crew at all. NASA also needs to launch its upcoming mission to Jupiters moon Europa pretty soon. Known as Europa Clipper, the mission is mandated by Congress to fly on the SLS by 2022. Lightfoot mentioned that Europa Clipper could come before the first crewed flight of the SLS. It just depends on if the Orion crew capsule, which will carry astronauts on the SLS, is ready before Europa Clipper is ready. If the Europa spacecraft comes first, then it could also fly on the small Block 1 rocket. Overall, Lightfoot hammered home to Congress that NASA has many different options now: It allows us to have the ability to fly SLS when were ready with whatever payload is ready to go.