NASA is investigating the possibility of putting astronauts on the first launch of its most powerful rocket ever – the Space Launch System (SLS) – which would dramatically speed up its plans to get humans back to the Moon, and one day to Mars.

In a major turnaround, the space agency is considering adding a crew of astronauts to Exploration Mission 1 (EM–1) – an orbital mission to the Moon that's currently scheduled to launch in September 2018, but until now was going to be crewless.

While that September 2018 deadline might now be too ambitious, given the upgrades that will need to be made to the SLS to accommodate humans, it's still a huge and abrupt change of plans in NASA's mission timetable.

Before the announcement, crewed journeys on the SLS and its accompanying Orion capsule had been planned for 2021 at the earliest.

The surprising new direction for the SLS – described as a "bombshell announcement" by NASA standards – is widely being seen as a sign of the Trump administration's declared interest in returning astronauts to the Moon.

Referencing President Trump's inaugural address commitment that the US will "unlock the mysteries of space", acting NASA Administrator Robert Lightfoot broke news of the plan this week, announcing a new study to "assess the feasibility" of adding an astronaut crew to EM–1.

"I know the challenges associated with such a proposition, like reviewing the technical feasibility, additional resources needed, and clearly the extra work would require a different launch date," Lightfoot explained in a NASA memo.

"That said, I also want to hear about the opportunities it could present to accelerate the effort of the first crewed flight and what it would take to accomplish that first step of pushing humans farther into space."

While it's too soon to say how a crewed EM–1 operation would alter mission parameters, the existing plan was scheduled to take about three weeks, with an uncrewed Orion capsule collecting data as it orbits the Moon for six days, at a distance of around 70,000 kilometres (43,495 miles).

It's possible that putting a crew on board both the SLS and the Orion could mean the flight ends up being shorter in duration, and it could bear a resemblance to a pretty famous precursor: the Apollo 8 mission in 1968 – the first time a human crew orbited the Moon.

Even with extra time to prepare the mission, there'll be an awful lot of work to be done. The Orion capsule intended for EM–1 doesn't currently contain a working life support system, and the SLS rocket hasn't been entirely graded for human launches.

But if those obstacles can be overcome, the new-look EM–1 could serve as an important testing ground to prepare for its successor mission, EM–2, which is set to take place three to five years later.

EM–2 would see NASA astronauts actually land on the Moon's surface for the first time since 1972.

And while these new missions might sound like do-overs of glorious NASA accomplishments from decades ago, the truth is that the stakes are actually more scientifically ambitious than ever before.

The SLS's ultimate purpose isn't just to ferry us over to Earth's satellite – it's to get humans to Mars one day.

Testing the spacecraft is one thing, but we also need to run checks on everything we'd need to actually live on the Red Planet – and the Moon's the closest thing to a trial run we're going to get.

So while there's a huge amount of detail for NASA scientists to still figure out with a crewed first launch of the SLS with Orion – or even if it's doable at all – the prospect that humans could be getting back to the Moon sooner rather than later is something we're definitely excited about.

"The magnitude of what we're doing with SLS and Orion is incredible," Lightfoot explains, "as are the capabilities we're creating for this nation, which will take humans farther than we ever have before."

Watch this space.