Thursday's flight of NASA's Orion capsule will mark the first in-space test of the first vehicle that's designed to carry humans beyond Earth orbit since Project Apollo — and the first step on a long road that could lead to putting astronauts on Mars. But the steps between now and then are definitely up in the air.
"The mission per se is great," Scott Pace, the director of George Washington University's Space Policy Institute, said of Orion's Exploration Flight Test 1, or EFT-1. "But the policy rationale for what one would do with these things is still up for debate."
The $370 million EFT-1 mission is due to send an uncrewed Orion on a 4.5-hour, two-orbit test run that zooms out to 3,600 miles (5,800 kilometers) and back. The craft will be launched from Cape Canaveral Air Force Station in Florida, atop a United Launch Alliance Delta 4 Heavy rocket.
A crucial phase of the test comes when Orion screams back through the atmosphere, slowing down from almost 20,000 mph (32,000 kilometers per hour) to a mere 17 mph (27 kph) when it splashes down in the Pacific Ocean off the coast of Baja California for recovery. About 1,000 sensors that have been built into the craft will monitor how well Orion's heat shield and other systems perform.
All those readings will be factored into the preparations for even more ambitious trips over the coming decades. The next Orion test — known as Exploration Mission 1 or EM-1 — is currently set for late 2017 or 2018. It will send a robotic capsule that's more fully fitted out on a trip around the moon and back.
That trip will be powered by NASA's Space Launch System, which is currently under development but is destined to become the world's most powerful rocket.
In 2021, astronauts are due to get on board for Orion's first crewed spaceflight, designated as Expedition Mission 2, or EM-2. And this is where the mission plan gets hazier.
Targeting an asteroid, Mars and more
Last year, officials suggested that EM-2 could carry astronauts to a rendezvous with an asteroid — which would have been relocated to a stable spot in the vicinity of the moon by a robotic tug launched years before. Such a mission would follow through on the Obama administration's plan to have astronauts visit a near-Earth asteroid by 2025.
However, NASASpaceflight.com reported last week that mission managers thought it would be unrealistic to do the asteroid rendezvous during Orion's first crewed test flight in 2021, and that 2024 or 2025 would be a more workable timetable. That would translate to Orion's EM-3 or EM-4 mission.
When asked about that schedule, NASA spokeswoman Rachel Kraft said it was too early to be specific.
"EM-2 will be the first test of the fully integrated Orion/SLS system with astronauts," Kraft told NBC News in an email. "We'll identify which specific mission will first send crews to the relocated asteroid once a target is identified."
NASA's current exploration plan calls for launching an SLS rocket every year or so. The NASASpaceflight.com report suggested that crewed missions may be intermixed with robotic missions that take advantage of the SLS's extra oomph — for example, launching a probe to Europa, one of Jupiter's ice-covered moons, in 2022 or 2023. Or going to ice-covered, geyser-spewing Enceladus in the Saturnian system. Or sending a spacecraft to bring samples back from Mars.
Such a scenario would suggest that astronauts might venture beyond Earth orbit on a schedule similar to the annual Super Bowl, or the biennial Olympics. But Jason Crusan, director of the advanced exploration systems division in NASA's Human Exploration and Operations Directorate, said the schedule for SLS missions was far from being set.
"To lay those out as a concrete sequence at this point in time is premature," he told NBC News.
Crusan said each mission opportunity would be planned with an eye toward developing and demonstrating the capabilities required for sending astronauts to Mars.
For example, engineers still have to design the transport vehicles and habitats that would be used for Mars missions. Figuring out how to put crew habitats that weigh several tons onto the Martian surface could take until the 2030s, said Jim Reuther, NASA's deputy associate administrator for programs in the agency's Space Technology Directorate.
Even as NASA builds and tests the components for Mars exploration, the agency's mission planners will be developing detailed plans for EM-2, EM-3, EM-4 and beyond — potentially leading up to missions to Mars and its moons in the 2030s.
Is there a course correction ahead?
Pace agrees that a spaceship like Orion is required to go beyond Earth orbit, and that a heavy-lift rocket like the SLS will be required to send astronauts to Mars. But he thinks NASA would be better off if it took a different route for exploration beyond Earth orbit.
"I think a more sensible program would be a human return to the moon, and eventually going to Mars, and that could include going to an asteroid as an excursion," he told NBC News.
It would be easier to get the world's other space agencies and private-sector partners involved in lunar exploration and exploitation, Pace said. Commercial ventures ranging from Bigelow Aerospace to the Golden Spike Company and the teams pursuing the Google Lunar X Prize are already looking into the potential for profits.
The White House and Congress have been through this discussion before: In 2004, President George W. Bush directed NASA to work out a back-to-the-moon plan. That's how the Orion concept got its start. But after President Barack Obama took office in 2009, the focus shifted away from the moon to center on near-Earth asteroids and Mars.
And at least one commercial venture has Mars fully in its sights. Elon Musk, the billionaire founder of SpaceX, has repeatedly said one of his life goals is to help make humanity a multiplanet species by sending settlers to the Red Planet — perhaps on the "Mars Colonial Transporter" that Musk is said to have in mind.
Could a SpaceX craft or some other commercial spaceship beat Orion to Mars?
"The question is, where's the funding supposed to come from?" Pace said.
Unless Musk is willing to spend his entire $11 billion fortune, plus billions more, he'll need outside backing to make his dream come true. That almost certainly means government support. And who knows? With political shifts looming ahead, there may well be shifts in the vision for space exploration as well.
"NASA is doing the best it can with the hand that it's been dealt," Pace said. "Ultimately, if there's going to be long-term human exploration, you're going to need to have both ends of Pennsylvania Avenue, at the White House and on Capitol Hill, in sync with each other. And they've not been."
Tip o' the Log to NASASpaceflight.com and Chris Bergin as well as Nathan Koga for their assistance, including permission to use Koga's graphic of the SLS and Falcon Heavy rockets.