Nasa plans nuclear spacecraft to blitz asteroid threat to Earth
Astronaut Scott Kelly spent a year on board the ISS and has come back biologically older and genetically different
NASA has drawn up plans for a huge nuclear spacecraft capable of shunting or blowing up an asteroid that may threaten to wipe out life on Earth.
The US space agency published details of its Hammer (Hypervelocity Asteroid Mitigation Mission for Emergency Response) proposal, an eight-ton spaceship that could alter the trajectory of a giant space rock.
Nasa has said previously that Earth is overdue a huge asteroid strike and systems are in place across the globe to map dangerous rocks as they move through the Solar System.
Last year, a 100ft asteroid named 2012TC4 passed within 27,000 miles of Antarctica, a distance that astronomers described as “damn close”.
In detailed plans published in the journal Acta Astronautica, Nasa and the National Nuclear Security Administration calculated the time and payload it would take to move or destroy the 1,600ft-wide asteroid Bennu.
Under the plan, the ship would ram a smaller asteroid to destroy it, or detonate a nuclear device to obliterate a bigger one. Nasa already has a space probe on route to Bennu to take samples and has been monitoring the asteroid since it was discovered in 1999.
Although there is only a slim chance it could hit the Earth, it is still considered to be an NEO, or Near Earth Object, which in any collision would hit the planet with the equivalent force of 1.45 gigatons of TNT.
The Atomic Energy Commission has shown that a 1 gigaton warhead, detonated 6 miles above the ground, could be expected to start fires over an area of more than 430,000 square miles, an area that is more than four times the size of Britain. Dante Lauretta, professor of Planetary Science in the Lunar and Planetary Laboratory at the University of Arizona, said Bennu’s impact would release “three times more energy than all nuclear weapons detonated throughout history”.
The study calculated that 7.4 years would be needed from building Hammer, to launching it to a point in space where the craft would hit the asteroid and destroy it.
NASA astronauts and identical twins Scott and Mark Kelly have shared a lot in their extraordinary lives.
Born a few minutes apart, they were both US Navy captains, both flew on the space shuttle and both spent time aboard the International Space Station (ISS).
But Nasa has found that life away from planet Earth has exacted a surprising toll. The pair are, it seems, no longer genetically identical twins. After Scott, 54, spent 340 days in space, experts found that seven per cent of his genes did not match those of his brother.
On being told the news, Scott said: “What? My DNA changed by seven per cent? Who knew? I no longer have to call Mark my identical twin brother”
It is known that astronauts’ bodies adapt to micro-gravity, but it was generally assumed that the effects wore off upon their return to Earth.
Scott landed in March 2016, and it appears his body has yet to return to normal. Some of the genes that seem to have changed permanently involved
DNA repair, bone formation and how the cells used oxygen. Nasa took the unique opportunity of having astronaut twins to learn more about the genetic changes of lengthy periods in space.
The long-term effects of space habitation are still unknown and the space agency said the experiment was a stepping stone for its mission to Mars. While Scott was away, experts monitored the brothers’ DNA. “We really see an explosion, like fireworks taking off, as soon as the human body gets into space,” said Dr Chris Mason, Twins Study investigator, of Weill Cornell Medicine.
“We’ve seen thousands of genes change. This happens as soon as an astronaut gets into space, and the activity persists temporarily upon return to Earth.”
He added that as well as understanding risks for space travel, the study could lead to finding ways to protect and fix genetic changes.
Nasa collected readings for metabolites, cytokines and proteins and linked space flight to stress from oxygen deprivation, increased inflammation and nutrient shifts, which affect genes.
Scientists also discovered that Scott’s telomeres – the caps at the end of chromosomes that shorten with age – stretched in space. But they shortened back to normal length within two days of landing back on Earth.
The study showed no cognitive difference between Scott and Mark after being on the space station.
However, overall results appear to show that Scott’s year in space had a slightly detrimental effect on him. Tests suggested immune cell inflammation which can lead to disease and there were signs he may be biologically older than his twin.
Dr Mason said his team found “hundreds of genetic mutations” unique to Scott since his mission as well as increased mitochondria in the blood, indicating damage to the power plants of cells and disruption of hundreds of “space genes”.
Researchers are now evaluating the impact the findings might have upon space travel to Mars.
‘We’ve seen thousands of genes change. This happens as soon as an astronaut gets into space’