Earth's orbit is a trash heap. Could lead to collisions, a junk cascade or even war
In January 2022, space watchers were startled when a Chinese satellite suddenly moved from its usual path around the globe, docked with a derelict spacecraft and flung it into what's known as a "graveyard orbit".
Shijian-21's move to get rid of the defunct weather satellite, Beidou-2 G2, was done during daylight hours, when it's hard for telescopes to observe satellites.
It's a manoeuvre that would typically be celebrated.
Decades of space flight have left the area above earth's stratosphere — the thermosphere and exosphere — increasingly cluttered, filled with dead satellites, abandoned pieces of rockets, and tiny pieces of spacecraft that have become dislodged.
There's a real need to clean up the area or face the increasing risk of space debris colliding with a live satellite, crippling vital communications, or global positioning systems.
But some observers viewed China's manoeuvre with deep suspicion.
If China could tow a piece of space junk out of orbit, it could also do the same to other live satellite, giving it an edge if a conflict broke out on Earth.
"Shijian-21 ... could be used in a future system for grappling and disabling other satellites," the head of the US Space Command, General James Dickinson, said at the time.
With tensions building in the Indo-Pacific, there's a new Space Race underway as major military powers try to safeguard their vital equipment floating around Earth's orbit.
There's also a growing push to establish protocols and rules to reduce tensions and misunderstandings in what is a lawless domain.
While the US, Russia and, more recently, China have dominated this arena, Japan is now shaping up to be a significant player.
Its military recently set up the Space Operations Group, while its civil agency, Japan Aerospace Exploration Agency (JAXA), is teaming up with private enterprises to establish its own debris-cleaning technology.
In June, Japan unveiled its first space security blueprint.
"For the sake of national security, we will dramatically scale up the use of space systems and ensure the safe and stable utilisation of the domain," the Prime Minister Fumio Kishida vowed.
For space security expert Yasuhito Fukushima, from Japan's National Institute for Defense Studies, it's just a start of things to come.
"The new Space Security Initiative clearly states that, looking at the conflicts of the 21st century, the use of space is directly linked to military superiority on Earth," he said.
The nightmare space scenario
There are some 27,000 pieces of orbital debris being monitored as they fly around Earth at a whopping 7.7 kilometres a second.
There are many more millions of pieces of junk that are too small to track.
Left unchecked, a worst-case scenario called Kessler Syndrome could emerge, where a collision in space sends debris flying, which causes another collision, and more debris.
The chain reaction could become so severe that Earth's orbit will become enveloped in an impenetrable field of space debris.
That would make it impossible to launch more satellites without them also being obliterated by the junk cloud.
In the 2013 blockbuster Gravity, a hail of junk kills George Clooney and sends Sandra Bullock hurtling through space.
"Then there is debris that is between 1cm and 10cm. This size debris can also cause a satellite to end its mission if it hits. There are approximately close to 1 million of them."
In 2009, a dead Russian satellite collided with an active US satellite, creating more than 2,300 pieces of debris.
Thankfully, collisions are rare and often avoidable.
But as more spacecraft enters the domain, including a rush of commercial operators like Elon Musk's SpaceX program, ensuring safe operations is increasingly difficult.
China has already complained about having to move its space station to avoid a collision with a Starlink satellite.
JAXA needs about two days to crunch the data to ensure a satellite being moved out of the way of space debris isn't simply put into the path of other piece of orbital junk.
"It's meaningless if it hits other debris," Mr Sakurai said.
"We have to make sure that even if it avoids the most dangerous debris, it won't hit other debris."
Is it possible to clean up space?
JAXA has teamed up with Tokyo-based Astroscale, which is trying to develop the world's first commercial space debris removal program.
There's also hope that as an industry leader, the teams can help establish standards for others to follow.
"There is no space police person cruising though [space], pulling over satellites that aren't following the rules," Astroscale's chief operations officer Chris Blackerby said.
"What we're focused on at Astroscale is increasing that communication. We want to see governments talking to each other. We want to see commercial companies interacting with each other.
"The key point here is transparency of operations."
Astroscale will launch a type of spacecraft, called ADRAS-J, from New Zealand this year, which will demonstrate how their spacecraft can shadow part of an old Japanese rocket.
"Finding that failed object in space, coming in closer to it, approaching it, getting close enough that you can understand the rotation rate, then coming in and capturing it," Mr Blackerby said.
Later tests would demonstrate how their spacecraft can grab a piece of debris and pull it towards Earth where it would harmlessly burn up upon re-entry.
Five large pieces of junk need to be removed annually to keep space debris stable, JAXA forecasts.
Astroscale has invented a so-called "docking plate", which the company hopes will become a standard fixture on future satellites, streamlining the whole debris-removing process.
"It's kind of like having the hitch on the back of a car where you can grab onto it and pull it out of the way," Mr Blackerby said.
"Right now, capturing a satellite is difficult, because it doesn't have a natural place where you can grab onto it."
'Unusual and disturbing' behaviour in space
It's not uncommon for satellites to "stalk" each other in space.
Last year, two Chinese satellites took off in opposite directions after they were approached by an American spy vessel.
One of the Chinese satellites turned back and watched the US orbital, media reports claimed.
In 2020, two Russian satellites moved from their orbital path to approach a US spy satellite, prompting it to flee.
"We view this behaviour as unusual and disturbing," the then head of the US Space Force, General John Raymond, told Time magazine at the time.
It's this type of behaviour Japan's Space Operations Group monitors.
Takaaki Yamamoto, 24, is part of Japan's Space Operations Group, which monitors the skies around the clock.
"There are no specific criteria at the moment to say what exactly is a suspicious move," he said.
"There is no rule that says it's illegal to come within a certain distance. We can't say, 'what are you doing so close?' or 'move out of the way'.
"We operate on the principle of responsible activities in space, so even if the movements are not suspicious, we're looking at whether or not they are physically dangerous to us."
Establishing these norms has become a priority for Japan.
Earlier this year, in Hiroshima, Japan along with its other Group of Seven nations called for "safe and sustainable use of outer space".
But militaries are also sharpening their tools in case of conflict. Even North Korea is trying to enter the fray.
"Especially since mid-2010, the US has been concerned about space becoming a war-fighting domain," space security expert Yasuhito Fukushima said.
"It's concerned that a war on Earth could spill over into space.
"Japan now shares this perception."
Russia's invasion of Ukraine has demonstrated just how important space is for military operations.
Ukraine has used US satellites for everything, from flying drones to firing the HIMARS rocket system.
It's also utilised commercial SpaceX Starlink satellites, prompting Russia to warn such satellites could be "legitimate" targets.
Mr Fukushima said in the event China uses force against Taiwan, triggering a broader conflict in East Asia, securing space superiority would be a priority.
"The US military is the most dependent on space for land, sea and air operations in the world," he said.
"By obstructing the use of space by the US military, it can hinder US military operations in the western Pacific, especially in the sea and air."
Rise of the 'satellite killers'
In recent years, China and Russia have both successfully tested so-called "satellite killers" to obliterate their dead vessels.
But the tests were roundly condemned because they unleashed thousands of pieces of space junk into orbit.
"There are various kinds of those anti-satellite weapons," the commander of Japan's Space Operations Group Kimitoshi Sugiyama said.
"[Among them are] direct ascent missiles, or electric magnetic wave jamming, and or robotic arms capturing, or even laser weapons."
As Earth's space becomes increasingly fraught, Japan's Space Operations Groups is expanding.
Its first squadron monitors activity in space, including space debris. The second squadron will investigate information about potentially threatening activities in space.
"Next year, we will have the new system, which detect the electric magnetic interference in a satellite," he said.
Commander Sugiyama would not be drawn the specific type of suspicious behaviour his agency had witnessed.
But he did state satellites passing "very close" to Japan's satellites was viewed with concern.
For now, his agency is working to put up a united front with partner countries, like the US and Australia.
"We have no national borders in outer space," he said.
"Japan and like-minded countries will try to make international norms to secure the stable use of outer space. We have to cooperate closely."
