SpaceX return: How Nasa astronauts' splashdown has changed the future of space travel

That's one quick drop for man; one giant splash for mankind.

The safe return of SpaceX's Crew Dragon is not on the scale of the moon landings, of course, but it could certainly be a step towards space travel successes of similarly soaring heights.

The capsule left Earth some two months ago, carrying two astronauts who were to visit the International Space Station but also carry out one of the most high-stakes tests possible: the final assessment of the capsule itself, conducting the mission it was built to do, and ensuring that it could go on to be approved for more regular Nasa missions.

It was not only a test of the capsule itself, but of Nasa's overarching Commercial Crew Programme. That has seen it turn to private companies – Elon Musk's SpaceX most famously, but others too – in an attempt to restore its former success in space travel.

In all, the mission marks a historic success: it is the first time that astronauts were sent from US soil since the Space Shuttle programme ended in 2011, and the first successful splashdown in 45 years, since the Apollo programme.

Nasa hopes that it will return the space agency and its space flight capabilities to those historic heights. It hopes that it will now be able to reliably and routinely fly astronauts to space from home, as it did with the Space Shuttle, and use that to explore more of the solar system, as with Apollo.

The collaboration between SpaceX and Nasa – where the private company builds the rocket and capsule, and the space agency directs and funds the mission as well as providing the astronauts – is its aim for doing that. It hopes that will allow for the full ingenuity and risk to be taken on by the private sector, while it gets to benefit from American-made spacecraft carrying US astronauts from its own facilities.

The space agency is already hailing the mission as proof that it works.

"Welcome home, Bob and Doug! Congratulations to the NASA and SpaceX teams for the incredible work to make this test flight possible,” said NASA Administrator Jim Bridenstine in a statement released after the successful splashdown.

“It’s a testament to what we can accomplish when we work together to do something once thought impossible. Partners are key to how we go farther than ever before and take the next steps on daring missions to the Moon and Mars."

Of course, nothing this big happens in one moment. The mission was hailed as a success as soon as the rocket successfully launched, and the test – while very high-stakes – was just the end of an extensive assessment process that has been ongoing since 2015.

Before that, Nasa's Commercial Program had been running for years, in the hope that such a breakthrough was possible. It was started 10 years ago and has included other companies, too – including Boeing, which plans crewed tests of its own soon.

The philosophical underpinnings of that programme run even further than that. They arguably began in failure, when Nasa and the US banked on the Space Shuttle being the future of space travel – and when that programme came to an end without the promised replacement, the space agency was forced to rely on buying tickets on Russian spacecraft to get its astronauts to the International Space Station.

There is of course nothing to say that the new programmes could end in similar disappointment. The space shuttle looked like the future until it did not, and public space agencies have still achieved far more success than any private company when it comes to travelling in space.

But they are much more likely, of course, to have great success. According to both Nasa and SpaceX, that success could lead to humans going to the Moon to live, and from there heading on to Mars; landing in the sea could be one little part of the grand path to explore further in our solar system than many ever dreamed possible.