It seems odd to ask if we are running out of space, but with growing deployments of satellites for communications in low Earth orbit (LEO) alone from Space X, Amazon, OneWeb and others, it is a query which is becoming increasingly significant.
The number of satellites at various orbits appears to be increasing rapidly. Data acquisition system manufacturer Dewesoft reported a total of 4,550 satellites in orbit at 1 September 2021, using figures compiled from the UCS Satellite Database, European Space Research Institute and the Space Foundation.
By end-2021, US-based environmental group The Union of Concerned Scientists reported a total of 4,852 satellites in various orbits, 4,078 of which were LEO birds, those located 400km to 1,200km above the earth’s surface.
And Stijn Lemmens, senior space debris mitigation analyst with the European Space Agency (ESA), told Mobile World Live (MWL) the tally stood at around 6,100 by August 2022.
With companies plotting constellations numbering at least in the hundreds of satellites, demand for space is beginning to look like it is at a premium.
Lemmens explained this alone poses challenges for current space traffic coordination systems, which largely still rely on various bodies like the ESA communicating with one another.
Discussions on a centralised global agency to handle coordination have been ongoing since the late 1970s, but “at the moment there is no mechanism or international treaty that would imply an easy way forward” on this, Lemmens explained.
Current treaties covering traffic coordination “put the responsibility firmly within nation states” and even if the situation changed, any group charged with centralising the task would take some time to get up and running, and may lack the teeth to fully enforce its policies, Lemmens said.
The present approach works, but Lemmens emphasised there is already a significant number of private and government initiatives underway exploring how best to gather and disseminate relevant data among satellite operators and other stakeholders.
Mark Dickinson, VP of Space Segment at Inmarsat (pictured, right), estimated the number of satellites in orbit “seems to go up by 100…every couple of weeks”, almost all of which is in the LEO range. He noted there are “entities around the world that track the number of objects, both active and debris”.
It is the latter which poses the greatest challenge in terms of ensuring availability of space: Dickinson explained the satellites themselves tend to be “actively” controlled, with each occupying “different orbital heights” and inclinations, “basically the angle that the orbit is to the equator”.
But there is something of a cascading effect involving debris, whereby the more birds are flown the greater amount of junk they create, a phenomenon which is far from novel.
In 1978, NASA scientist Donald Kessler theorised there is a point of critical mass for space debris, whereby collisions between existing objects create more debris and so further impacts.
The so-called Kessler syndrome predicts huge swathes of space may become inhospitable to satellites and other objects as a result of this cascading effect.
Lemmens explained current tracking systems are capable of detecting objects of 5cm to 10cm, but noted items smaller than this can still “be mission critical when it impacts”, potentially creating “new fragmentation debris” alongside damage to larger craft.
While today’s satellites are smaller than their predecessors, the scale of the constellations planned means they remain at risk of colliding with existing space debris.
Lemmens said various organisations like the ESA are involved in monitoring space debris and plotting any potential collisions to enable evasive manoeuvres to be taken.
But there are limitations to the approach, including differences in monitoring systems. Lemmens noted most agencies have taken a practical approach to sharing information, a system he acknowledged as functional but far from ideal: “it works because it has to”.
Work is underway to automate and standardise detection systems, which Lemmens believes will ultimately ease the pressure on individual agencies. And he noted a solution to keeping track of space debris does not necessarily need to involve large bodies like the ITU.
Modelling how space debris might develop as further large LEO constellations are deployed is like looking into a crystal ball, Lemmens said. “You just try to predict the trends and try to see the influence”.
Whether imperfect or not, Lemmens explains “we have probably crossed this point where slowly but surely the amount of debris” in orbit increases. He noted there is already around 60 years-worth of space junk which, if left as is, will result in higher levels of debris.
This presents something of a problem for regulators: Lemmens explained current rules “are to stop or reduce the growth rate” of debris, “but it doesn’t invert”.
“So, we are already in a situation where if we want to go back to a state where the amount of debris goes down we have to talk about active remediation, which simply means designing missions to go and pick-up larger pieces of space debris, like large satellites or large rocket bodies and take them out”.
For now, collision avoidance has “become a fact of life” which Lemmens believes proves the case for greater coordination and talks on “how to implement far stricter requirements” covering the reliability of spacecraft and the time allowed to deorbit objects once defunct.
While Lemmens argues the overall industry must “step up” its response to rising levels of debris, Dickinson explained there is more at play when considering the amount of space available.
He noted LEO satellite operators must “overbuild” their constellations to “meet the peak” demand because the birds are rotating around the earth.
Dickinson noted to double the capacity over a specific area like a city, “you have to double the number of satellites in the constellation”.
Beyond the number of satellites required to get services off the ground are further issues which impact the amount of space available. Dickinson explained the typical operating lifespan of LEO birds is between five and seven years, making end of life planning essential to ensure they do not add to current debris.
A side, but important, element here is the business model. With such short lifetimes, any satellite operator must embark on a near constant round of launches and decommissioning which Dickinson noted is a hefty strain on capex.
It is a cycle of investment Dickinson explained cannot be avoided for companies targeting businesses or government contracts. He noted it can take significant effort to install compatible terminals in industries including aviation or maritime, meaning customers “want to be able to have confidence” the “service is going to be there in ten years’ time”.
The market dynamics almost certainly mean service providers will require several generations of satellites, maintaining the pressure on their bank balances.
As a result, today’s satellites “need to be quite cheap”, Dickinson explained. Many aim to keep costs in check by simply removing some of the redundancy systems found in birds with longer operational lifespans.
One such area is the amount of fuel each satellite carries to conduct orbital or collision-avoidance manoeuvres.
Fuel requirements vary depending on the height of the satellite within the LEO range. Dickinson explained birds flown at around 400km to 500km above the earth’s surface will “essentially come back naturally” into the atmosphere over a period of up to ten years after their operational life.
The downside of operating in this window is “you need very many more satellites”. By contrast, those flying in the higher-tiers of the LEO range require fewer birds because each one “can see more of the earth”.
It seems there is no panacea to be had, with Dickinson noting high flying birds will require operators to plan for their return to the atmosphere. “If you launch a satellite, at the end of its mission you have to be able to…decommission it safely within 25 years”.
There are calls for such timelines to be cut: the US Federal Communications Commission (FCC) recently proposed defunct LEO satellites should be removed within five years.
Dickinson welcomed the move, though noted it “only modestly improves the sustainability situation”.
“As an industry, we should strive for even more unambiguous goals of months rather than years for this tidy-up”, to minimise the risk “from potential debris generating collisions”.
The FCC is not alone in reviewing procedures Dickinson said were established 20 years ago when constellations were smaller. Swift clean-up is preferable “because if your satellite is not controlled then it’s a piece of debris waiting for a collision”.
Like Lemmens, Dickinson noted there are challenges in terms of analysing the risk of collisions and informing all relevant parties. But he also noted challenges in ensuring no entity monopolises specific orbits.
There are, of course, environmental elements to be considered. Dickinson noted Inmarsat is increasingly bringing climate change into its conversations on space sustainability, highlighting a “tension between the commercial side” where companies “want to be able to get these orbits and claim for themselves, coupled with the sustainability side of it”.
The fast-pace of deployments is hiking pressure for a regulatory overhaul, because the speed with which rules are implemented now lags operating companies’ ambitious plans, he said.
OneWeb agrees. A representative told MWL the number of companies vying for a slice of the space communications market is a good thing in terms of keeping pricing keen and service competitive, but argued there “is room for international collaboration and smart regulation to address the rapid acceleration of commercial space activity”, with licensing practices also ripe for improvement.
“Industry and governments must work together to establish internationally-adopted design and operational practices”, the spokesperson added.
OneWeb’s representative noted concerns over space debris and environmental damage is one reason it opted to occupy the upper-tiers of the LEO range. “We have spaced our orbital planes at different altitudes to minimise operational complexity and improve overall safety”.
“We share the concern about space debris,” the representative continued, adding it is the smaller, untraceable fragments which pose “the greatest threat to space operations”.
The company teamed with Japan-based debris clean-up specialist Astroscale, and UK and European space agencies to launch a service to remove space junk “towards the end of 2024”. It is also employing a collision avoidance product from mapping company LeoLabs “which provides real-time data about the location of other satellites and space debris” to deliver “safer and more sustainable” LEO operations.
While the satellite sector is well aware of the current challenges, the LEO gold-rush is polarising debate and accelerating the need for solutions to a debris problem which is already restricting the amount of space on offer.
The editorial views expressed in this article are solely those of the author and will not necessarily reflect the views of the GSMA, its Members or Associate Members.