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Nasa reaches for the stars with nuclear-propelled spacecraft
Nasa is hoping to build a nuclear propulsion system which would allow a spacecraft to travel to the nearest star.
While humanity has explored large parts of our own Solar System, the distances to another star system are, literally, astronomical.
Nasa's Voyager 1 became the first spacecraft to venture into interstellar space in 2012.
But even if the 10-miles-per-second probe were heading in the right direction, it would take it 70,000 years to reach our closest star Alpha Centauri, which is 4.37 light years away, or 25 trillion miles.
However, Dr Thomas Zurbuchen, associate administrator at Nasa's Science Mission Directorate, believes that it might be possible.
Speaking to The Sunday Telegraph at the launch of the Solar Orbiter probe last week, Dr Zurbuchen said Nasa should move away from missions that could be handled by private companies and instead focus on answering the big scientific questions.
"Nasa is not a space tourism company and we're not the same agency that we were during the time of Apollo," he said. "We should be doing things that there isn't a business case for, such as designing a new propulsion system that could take a probe to a star.
"We know there are planets there and we should be exploring them. It's not going to be easy and we haven't got it figured out yet. But that's the direction we should be heading."
Dr Zurbuchen continued: "It's likely this would be a legacy project that we won't see happen in our lifetime, but it's something we should be thinking about and planning for."
Scientists are keen to reach the binary Alpha Centauri star system as we now know it contains rocky planets in the "Goldilocks zone" which is neither too hot nor too cold for life to thrive.
Nasa first suggested a mission to the star system in 1987, when it launched Project Longshot, an unmanned probe designed to enter orbit around Alpha Centauri B in as little as 100 years, but it was abandoned the following year.
More recently, before his death, Professor Stephen Hawking announced plans to design a tiny "nanocraft" fitted with a small sail that could travel to the system within 20 years.
The craft would be powered from Earth using a huge array of laser beams fired up into space, coming together to form a 100 gigawatt beam of light which would send the tiny craft hurtling out of the Solar System at speeds of 100 million miles per hour.
After Hawking announced the plan in 2016, a panel from the US House of Representatives, which oversees Nasa's budgets, called on the space agency to attempt its own mission to Alpha Centauri in 2069 - the centenary of the Apollo 11 moon landing.
In a report the panel said Nasa should "study and develop propulsion concepts that could enable an interstellar scientific probe with the capability of achieving a cruise velocity of 0.1c (10 per cent of the speed of light)".
At the time the panel suggested developing a propulsion system based on nuclear fusion, yet until now there was little clue that the space agency was actively looking into the possibility.
The fastest spacecraft so far launched into space, the Helios probes, travelled at 155,000 miles per hour, but even at that speed it would still take 18,000 years to reach Alpha Centauri.
Dr Zurbuchen said that although traditional space agencies could no longer compete with the resources of SpaceX or Blue Origin, he hoped scientists would still choose to be a part of such programmes. "If we can help each other then we should," he added.