But that’s exactly what has just been successfully achieved in a historic “planetary defense” mission led by the US space agency Nasa.
Science fiction has become science fact.
Project Dart (Double Asteroid Redirection Test) has been years in the planning, designed to discover whether humans could change the trajectory of a celestial body headed on a collision course with Earth.
The 535-foot-wide asteroid Dimorphos, a small moon of the larger, 2,560-foot-wide asteroid Didymos, was not a threat to Earth.
It was chosen as a target because its short orbit time would allow experts to quickly assess whether a direct hit from the ship had altered its course.
Live images were broadcast from Dart, a craft about the size of a vending machine, showing its final approach to the asteroid and the moment of impact, in the early hours of September 27, time of the United Kingdom.
Traveling at 14,000 mph, the unmanned spacecraft was destroyed when it crashed into the surface of Dimorphos.
This week NASA announced that the experiment had been a success, confirming that the impact had altered Dimorphos’ orbit around Didymos by 32 minutes, shortening it from 11 hours and 55 minutes to 11 hours and 23 minutes
In a briefing at the organization’s headquarters in Washington, NASA Administrator Bill Nelson described it as “a watershed moment for planetary defense and all of humanity.”
He said: “We all have a responsibility to protect our home planet. After all, it’s the only one we have.
“This mission shows that NASA is trying to be ready for whatever the universe throws at us.”
Lori Glaze, director of the agency’s Planetary Science Division, added: “This result is an important step in understanding the full effect of Dart’s impact with its target asteroid.
“As new data comes in every day, astronomers will be able to better assess whether, and how, a mission like Dart could be used in the future to help protect Earth from an asteroid collision if we ever discover that one set us on our way.”
The research team is still gathering information from observatories and other facilities around the world and updating the results to improve accuracy.
Professor Colin Snodgrass, an astronomer and planetary scientist at the University of Edinburgh’s School of Physics and Astronomy, is part of the international team working on the world-first project and helping to gather information.
He leads a team of scientists who have been manning telescopes in strategic locations, observing the progress of the mission and documenting the aftermath.
He returned to Scotland on the “night of the impact”, but was in constant contact with colleagues on the ground in Chile and Kenya and watched the NASA live feed.
But despite being alone in his office in Edinburgh, he found it an unforgettable experience.
“It was all very exciting,” he said.
Observers in Kenya were able to see the actual moment of impact through the telescope.
“They could see it getting brighter before their eyes.
“It became brilliant almost instantly, which was a bit of a surprise.
“Most of us expected it might take longer.
“We thought we would see some difference, some change in brightness, but we wouldn’t see the sudden cloud of dust coming off the thing.
“They could see the dust cloud forming live as they watched — this initial cloud, which is the high-velocity ejecta that had been thrown up on impact.
“After that, they’ve been watching how the long tail of larger particles (the slowest ejection, built up over days and weeks) has been growing.
“At the moment of impact, you see this sudden puff as it throws things at high speed and then you get the longer process of growing this tail, which is now thousands of kilometers long and we can still see with telescopes.”
Professor Snodgrass emphasized the importance of the experiment.
“It’s a test of the technology,” he said.
“If we saw one of these things coming our way, could we move it out of the way?
“And the test shows us that yes, we can, we can change its orbit if we need to.”
He also quickly made sure that the planet was not in imminent danger of being hit by a giant asteroid that could wipe out all life.
“All the really big asteroids, the mass extinction ones, we know where they all are,” he said.
“They are all big enough to be seen with telescopes for years.”
But he admitted there is a “slight concern” about much smaller asteroids, because one hit could do a lot of damage, and scientists haven’t found them all yet.
“They’re the ones we think about a bit more,” Professor Snodgrass said.
“Didymus, this is the kind of ladder you wouldn’t want to fall into your city.
“It would have the energy equivalent of a nuclear bomb, so it would cause local and regional devastation.
“It’s not the kind of size that would cause a mass extinction, it would kill all kinds of dinosaurs – that one was a few kilometers across.
“We’re constantly searching, scanning the skies, and we’re finding more of these little ones all the time.
“But we haven’t found any that come close to us yet.
“Eventually, though, we’re going to find one that’s going in our direction and it’s likely to be that kind of size, so that’s why this experiment is useful: it’s testing the technology to move an asteroid that’s the kind of size that’s realistic. arrive at some point.”
Experts hope we would have some warning before any potential strike, possibly decades, giving time to take defensive measures.
“You’re not likely to find one and go, are you, it’s coming next week,” he said.
“But if we spot one that’s going to be here next week, there’s probably not much we can do about it.
“You should just move everyone out of this place and hope there’s nothing you want to keep.”
As part of the Dart mission, the Edinburgh team took charge of the four telescopes of the European Southern Observatory’s Very Large Telescope, based in the Atacama Desert in northern Chile.
They also created a new observatory in Kenya, which will have a lasting legacy in the country.
Scottish academics have been helping train a new generation of planetary scientists there and handed over the keys to the new observatory when they left this week.
Professor Snodgrass said the Dart project has other benefits besides protecting the land.
“There’s a lot of science that comes out of it,” he said.
“The reason we’re working on this and trying to study asteroids and comets is because we’re interested in them scientifically.
“The history of the solar system, how the planets formed, all that kind of stuff—you get a lot of clues about that kind of stuff by studying asteroids, these little remnants of when the planets were made.
“And this experiment has told us a lot about the kind of physical properties of the asteroid, the internal structure, all these things that you couldn’t do without this big experiment of punching a hole in the side.
“So scientifically it’s very valuable as well as having a ‘planetary defense in case we ever need it’ approach.
“The project has a double use.
“And all these cool things about having a telescope in Kenya also have a dual use.
“The telescope stays out there and we’re doing all this work with the local university, we’re training astronomers in the country, which didn’t have many astronomers.
“Some Kenyan students are still there now, operating the telescope afterwards
The Edinburgh team is coming home.
“We taught them how to use it, we left them the keys and they left.
“They’re really great, an enthusiastic group. It’s really nice to see that.
“It’s been a very nice positive extra to come out of the Dart project.”
The professor also admits to being a secret fan of sci-fi movies like Armageddon and Deep Impact, both of which have plots that echo the purpose of the darts mission.
“I love them, especially the really terrible ones,” she said.
“You just have to turn your brain off a little bit.
“You know it’s all nonsense, but it’s fun, it’s entertaining nonsense.”