Source: The Guardian

Next year, Nasa will launch what all involved hope will be the most impactful space mission to date. The Double Asteroid Redirection Test (Dart) is designed to smash headlong into its target. It’s an attempt to deflect an asteroid as a test of what to do if we spot a similar space rock on a collision course with our planet.

It’s hardly news we want to hear at a time of so many domestic problems, but the threat from near-Earth asteroids is just one of a string of dangers that the planet and its technology are facing from space. Explosions on the sun create “space weather” that can play havoc with our satellites and other electrical systems, while the growing amount of space debris imperils the satellites that we all invisibly rely on.

The truth is our way of life utterly relies on space. The UK government now classes space as one of the nation’s 13 critical infrastructure sectors. And it needs protecting.

This November, science ministers from the various countries that belong to the European Space Agency (Esa) will gather in Seville, Spain, to decide the agency’s funding and priorities for the next three years. Attending the meeting is not something that depends on Brexit. Esa is an independent organisation from the EU, and the UK has every intention of staying a member no matter what happens on 31 October. Included in that will be the creation of a comprehensive €200m a year programme of planetary defence.

One spacecraft hits the asteroid, the other measures what happens. Nasa and Esa collaborate to split the cost

If approved, it would begin with a mission called Hera. This would investigate the aftermath of Nasa’s Dart impact, collecting enough data to turn the impact test into a workable asteroid defence programme. And that’s not all.

Called Space Safety, the programme also proposes missions to warn us against space weather and begin the removal of space debris. “All threats are viewed as equally important,” says Holger Krag, head of the programme.

But that might not be the view of the various member countries, where funding is likely to be limited. If the full €200m is not forthcoming, ministers will have to decide which threats to tackle and which ones to simply cross our fingers over.

The choices are:

Near-Earth asteroids

On Thursday 25 July, an asteroid 57-130 metres across missed our planet by just one-fifth of the distance to the moon. In astronomical terms, that’s a hair’s breadth. Had it hit us, the devastation would have been staggering.

Astronomers call asteroids of this size “city killers”. It’s not hard to see why. In February 2013, one roughly 20 metres across appeared in the sky above the Russian city of Chelyabinsk. It exploded at an altitude of around 30 kilometres, creating a shockwave that shattered windows and injured around 1,500 people.

What makes the asteroid of 25 July so disturbing is that if it had appeared over Chelyabinsk, instead of breaking windows, it would have toppled whole buildings. But there’s hope.

“We are the first generation of life on the Earth that can actually do something about this risk,” says Krag.

In the early 2000s, Esa convened a panel of experts to assess how best to deal with an incoming asteroid. The ideas they looked at ranged from the bizarre – painting an asteroid so that the way it reflected light would gradually shift its orbit – to the frightening – repurposing nuclear weapons to melt part of the asteroid so that the heat it released would push the rock into a different orbit.

The team came to the conclusion that the most viable option was the so-called kinetic impactor. In other words, you drive headfirst into the asteroid and knock it out of the way.

Prof Alan Fitzsimmons of Queen’s University Belfast was part of that original team. “The best thing we can do at the moment to protect the Earth is search for these objects and find them, study their physical properties so that we know what’s likely to hit us and see if we can move one,” he says.

This is how Dart and Hera came about. One spacecraft hits the asteroid, the other measures what happens. Nasa and Esa collaborated in order to split the cost. Together, the two spacecraft make up the Asteroid Impact and Deflection Assessment (Aida) mission. They were supposed to launch together but while Nasa went ahead and is now preparing for liftoff, a previous incarnation of Hera was narrowly rejected by Europe’s science ministers at the last funding conference in 2016.

This set the European effort back three years but all is not lost. “Right now, we can just about do it if we get approval this year,” says Fitzsimmons.

Space weather is on the National Risk Register, a publication that lists significant potential threats to the nation

If the ministers say no again, the mission is dead. Nasa will continue with Dart and use telescopes on Earth to measure the change in its target’s orbit. But according to Fitzsimmons, that seriously diminishes the value of the mission.

Hera’s observations will reveal the composition and physical structure of the target asteroid. This is vital data for planning how best to deflect another asteroid when one is actually found to be on a collision course. Without Hera, any future deflection attempt would be more “hit it and hope” than precise science.

“This is about protecting the planet and it’s about time all the nations of Earth, including Europe and the UK, stepped up to the plate and helped out,” says Fitzsimmons.

Space weather

Had you been alive 160 years ago today, you would have been about to witness something truly astonishing. As night fell on 1 September 1859, Earth’s atmosphere lit up with one of the biggest displays of the northern and southern lights. Simultaneously, the technology of the day failed spectacularly. Compasses spun uselessly and phantom electricity surged through the telegraph lines stunning operators unconscious and setting fire to equipment and offices.

The only clue to what had happened came from the English amateur astronomer Richard Carrington, who observed a giant disturbance on the sun from his observatory in Redhill, Surrey.

This was the discovery of solar flares, space weather and the danger they pose to electronic technology. Space weather is produced by magnetic activity on the sun, which drives a turbulent wind of subatomic particles out into space.

These particles carry electrical energy that can burn out sensitive electronics – and our vulnerability to them has only increased. Satellites and power grids are particularly susceptible to damage and destruction by space weather.

In 1989, a solar storm caused over $10m of damage to equipment in the Hydro-Québec power grid, leaving six million people without power for nine hours. As bad as that seems, it’s the events of the 19th century that have researchers worried.

“The Carrington event is a reasonable worst-case scenario,” says Mike Willis of the UK Space Agency.

In 2017, the policy and economics consultancy London Economics reviewed the impact to the UK of a disruption to global navigation satellite services such as Galileo or GPS. They concluded that a five-day disruption would cost the country £5.2bn. Space weather appears on the National Risk Register, a Cabinet Office publication that lists what it regards as significant potential threats to the nation.

At present, the world relies on an ageing population of science satellites to warn us of incoming space weather. But it’s hardly an early warning system and the spacecraft are all showing signs of wear and tear.

“We’re living on borrowed time. If we lose the science missions, we will be effectively blind. And we don’t want to be in that situation,” says Willis.

To avert this danger, the UK invested €22m at Esa’s 2016 ministerial conference to take a prominent role in studying a mission that would act as a space weather watchdog. Known as the L5 mission, it would be stationed tens of millions of kilometres away so that it can look into the space between the sun and Earth.

L5 will show us the incoming space weather. This will allow us to give early warnings so that payloads and other critical systems can be placed into safe modes, then reactivated once the danger has passed. The mission is now part of Esa’s Space Safety programme and so will be placed before all European ministers in November for approval. “Bringing other Esa member countries on board is something we have to do,” says Willis.

Space debris

This particular problem is all of our own making. When the space race began, the US and Russia blasted rockets into orbit willy-nilly. As other nations started building their own satellites, they too launched at random. No one cared about what happened to the spacecraft after the mission ended because, as Douglas Adams wrote: “Space is big.”

It turns out that while Adams is right about the universe as a whole, the orbits around the Earth are not inexhaustible. There are now well over an estimated million pieces of space debris larger than 1 centimetre in orbit around Earth. Each one has the potential to collide with and destroy another satellite, creating hundreds of thousands more pieces of space debris.

Around half the debris in space today comes from just two incidents. The 2007 anti-satellite test in which China blew up a satellite of its own with a missile and an accidental collision in 2009 between a defunct Russian satellite and a working US one.

Space engineers talk about the Kessler syndrome, a nightmare scenario which envisages so much space debris being generated that we simply cannot put more satellites into orbit. Any we did launch would be destroyed by random collisions, creating more space debris and making the situation worse. Averting the Kessler syndrome is something Esa has been thinking about for a long time.

“We were one of the first agencies together with Nasa to highlight this problem,” says Holger Krag.

But progress has been slow, partly because the law is extremely lax about littering space. Now, however, as part of the proposed Space Safety programme, Esa thinks it has found a way to get the ball rolling. The idea is simple.

First, it demonstrates that removing space debris is possible. Then it lobbies for international space law to be changed to say that a satellite’s owner must de-orbit the craft at the end of its mission. If the owner fails to do this, they have to pay an industrial contractor to go and remove the satellite for them.

Elon Musk’s plan is to launch 12,000 tiny satellites in very low orbits; other companies envisage similar fleets

“That would automatically generate a market. And that’s what we want to prepare for,” says Krag.

So the mission Esa envisages for this strand of the Space Safety programme is different from the other two. Instead of specifying the details of how the mission should complete its task, it wants industry to come up with those ideas. Esa will then lend its expertise to help develop the necessary technology but industry will own the missions.

“We hope to break the cycle between legislators waiting for de-orbit technology to be available and the law that is not yet tight enough to enable this market to begin,” says Krag.

As well as the debris that is already up there, the proposed mega-constellation of hundreds or thousands of small satellites only makes the problem more urgent. Elon Musk’s SpaceX plan is to launch 12,000 tiny satellites into very low orbits to supply low-latency telecommunications; other companies are planning similar fleets. All of them carry the potential to vastly increase the amount of space debris, making the Kessler syndrome more likely than ever.

Again, Europe’s science ministers will decide in November whether this is a problem they want to tackle.