Tag Archives: space junk

The Traffic Congested Space: Collision Avoidance

On September 3, 2019, it was the first time that European Space Agence (ESA) performed a ‘collision avoidance manoeuvre’ to protect one of its spacecraft from colliding with a satellite in a large constellation,  a SpaceX satellite in the Starlink constellation.  Constellations are fleets of hundreds up to thousands of spacecraft working together in orbit. They are expected to become a defining part of Earth’s space environment in the next few years.  As the number of satellites in space dramatically increases, close approaches between two operated spacecraft will occur more frequently. Compared with such ‘conjunctions’ with space debris – non-functional objects including dead satellites and fragments from past collisions – these require coordination efforts, to avoid conflicting actions. 

Today, the avoidance process between two operational satellites is largely manual and ad hoc – and will no longer be practical as the number of alerts rises with the increase in spaceflight.
 “This example shows that in the absence of traffic rules and communication protocols, collision avoidance depends entirely on the pragmatism of the operators involved,” explains Holger Krag, Head of Space Safety at ESA.   “Today, this negotiation is done through exchanging emails – an archaic process that is no longer viable as increasing numbers of satellites in space mean more space traffic.”

ESA is proposing an automated risk estimation and mitigation initiative as part of its space safety activities. This will provide and demonstrate the types of technology needed to automate the collision avoidance process, allowing machine generated, coordinated and conflict-free manoeuvre decisions to speed up the entire process – something desperately needed to protect vital space infrastructure in the years to come.

Data is constantly being issued by the 18th Space Control Squadron of the US Air Force, who monitor objects orbiting in Earth’s skies, providing information to operators about any potential close approach.  With this data, ESA and others are able to calculate the probability of collision between their spacecraft and all other artificial objects in orbit. 

In August 2019, the US data suggested a potential ‘conjunction’ [collision] at 11:02 UTC on Monday, 2 September, between ESA’s Aeolus satellite and Starlink44 – one of the first 60 satellites recently launched in SpaceX’s mega constellation, planned to be a 12 000 strong fleet by mid-2020.  As days passed, the probability of collision continued to increase, and by Wednesday 28 August the team decided to reach out to Starlink to discuss their options. Within a day, the Starlink team informed ESA that they had no plan to take action at this point.**  ESA’s threshold for conducting an avoidance manoeuvre is a collision probability of more than 1 in 10 000, which was reached for the first time on August 29, 2019 evening.  An avoidance manoeuvre was prepared which would increase Aeolus’ altitude by 350 m, ensuring it would comfortably pass over the other satellite, and the team continued to monitor the situation.

On September 2, 2019, the commands triggered a series of thruster burns at 10:14, 10:17 and 10:18 UTC, half an orbit before the potential collision.  About half an hour after the conjunction was predicted, Aeolus contacted home as expected. This was the first reassurance that the manoeuvre was correctly executed and the satellite was OK.

Since the first satellite launch in 1957, more than 5500 launches have lifted over 9000 satellites into space. Of these, only about 2000 are currently functioning, which explains why 90% of ESA’s avoidance manoeuvres are the result of derelict and uncontrollable ‘space debris’.    In the years to come, constellations of thousands of satellites are set to change the space environment, vastly increasing the number of active, operational spacecraft in orbit.  This new technology brings enormous benefits to people on Earth, including global internet access and precise location services, but constellations also bring with them challenges in creating a safe and sustainable space environment.

This example does show the urgent need for proper space traffic management, with clear communication protocols and more automation,” explains Holger.  “This is how air traffic control has worked for many decades, and now space operators need to get together to define automated manoeuvre coordination.”  As the number of satellites in orbit rapidly increases, today’s ‘manual’ collision avoidance process will become impossible, and automated systems are becoming necessary to protect our space infrastructure.

**On August28th, 2019, SpaceX informed ESA via email that the company did not intend to move the Starlink probe.   At that time, the probability of collision was about 1 in 50,000, according to SpaceX, which is too low to require any preventive action.  The ESA contacted SpaceX daily about its evolving calculations, but the agency did not receive any additional replies after the original email response. SpaceX acknowledges that it failed to communicate due to a bug in its communication system and missed the emails about a higher probability of collision.

Excerpts from ESA Spacecraft Dodges Satellite Constellation, ESA, Sept. 3, 2019 &

A bug in SpaceX’s communication system kept the company in the dark about potential satellite collision, The Verge, Sept. 4, 2019

The Space Rat Race

India, Japan and other space-faring countries are waking up to a harsh reality: Earth’s orbit is becoming a more dangerous place as the U.S., China and Russia compete for control of the final frontier…New Delhi is nervous because China has made no secret of its desire for influence in the Indian Ocean. China set up a naval base in Djibouti, a gateway to the ocean at the Horn of Africa. It secured a 99-year lease to the port of Hambantota in Sri Lanka. It is deeply involved in development projects in Maldives.

India has established itself as a player in the budget satellite business. It even put a probe into orbit around Mars in 2014, in a U.S.-assisted project that cost just $76 million. But it is scurrying to enhance its ability to monitor China’s activities, and the partnership with Japan is part of this.  Another sign that space is becoming a defense focus for India came on Dec. 19, when the country launched its third military communications satellite, the GSAT-7A. The satellite will connect with ground-based radar, bases and military aircraft, along with drone control networks.

China’s success in landing a craft on the far side of the moon on Jan. 3, 2019 came as a fresh reminder of its growing prowess. In late December, China also achieved global coverage with its BeiDou Navigation Satellite System. Only the U.S., Russia and the European Union had that capability.China aims to launch a Mars explorer in 2020 and complete its own Earth-orbiting space station around 2022.  In the back of Indian and Japanese officials’ minds is likely a stunning test China conducted in 2007. Beijing successfully destroyed one of its own weather satellites with a weapon, becoming only the third nation to pull off such a feat, after the Soviet Union and the U.S.

In December 2018, President Donald Trump ordered the Department of Defense to create a Space Command, widely seen as a precursor to a full-fledged Space Force.  There were 1,957 active satellites orbiting Earth as of Nov. 30, 2018 according to the Union of Concerned Scientists, a nonprofit U.S. advocacy group. America had the most by far, with 849, or 43% of the total. China was No. 2, with 284, followed by Russia with 152.  Japan and India had a combined 132 — 75 for the former and 57 for the latter.

Excerpts fromNUPUR SHAW India and Japan awaken to risks of superpower space race, Nikkei Asian Review, Jan. 8, 2019

Killing Machines: Tiny Spy Satellites

As long as we’ve been launching spy satellites into space, we’ve been trying to find ways to hide them from the enemy. Now, thanks to the small satellite revolution—and a growing amount of space junk—America has a new way to mask its spying in orbit…

The National Reconnaissance Office, the operator of many of the U.S.’s spy sats, refused to answer any questions about ways to hide small satellites in orbit.  In 2014, Russia launched a trio of communications satellites. Like any other launch, spent stages and space debris were left behind in space. Air Force Space Command dutifully catalogued them, including a nondescript piece of debris called Object 2014-28E.  Nondescript until it started to move around in space, that is. One thing about orbits; they are supposed to be predictable. When something moves in an unexpected way, the debris is not debris but a spacecraft. And this object was flying close to the spent stages, maneuvering to get closer.  This fueled speculation that the object could be a prototype kamikaze-style sat killer. Other less frantic speculation postulated that it could be used to examine other sats in orbit, either Russia’s or those operated by geopolitical foes. Either way, the lesson was learned…

Modern tracking radar is supposed to map space junk better than ever before. But small spy satellites that will hide in the cloud of space debris may go undetected, even by the most sophisticated new radar or Earth-based electronic signals snooping.

Excerpts from Joe Pappalardo, Space Junk Could Provide a Perfect Hiding Spot for Tiny Spy Satellites, Popular Mechanics, Nov. 30, 2018

Space Junk Removal

The first experiment designed to demonstrate active space-debris removal in orbit reached the International Space Station on April 4, 2018 aboard SpaceX’s Dragon capsule.    The RemoveDebris experiment, designed by a team led by the University of Surrey in the U.K. as part of a 15.2 million euro ($18.7 million), European Union (EU)-funded project, is about the size of a washing machine and weighs 100 kilograms (220 lbs.).

It carries three types of technologies for space-debris capture and active deorbiting — a harpoon, a net and a drag sail. It will also test a lidar system for optical navigation that will help future chaser spacecraft better aim at their targets.

“For this mission, we are actually ejecting our own little cubesats,” Jason Forshaw, RemoveDebris project manager at the University of Surrey, said last year. “These little cubesats are maybe the size of a shoebox, very small. We eject them and capture them with the net.”

“We are testing these four technologies in this demonstration mission, and we want to see whether they work or not,” said Forshaw, referring to the harpoon, net, drag sail and lidar. “If they work, then that would be fantastic, and then these technologies could be used on future missions.”

Some 40,000 space objects — the vast majority of which are defunct satellites and fragments from collisions — are currently being tracked by the U.S.-based Space Surveillance Network. It is estimated that some 7,600 metric tons (8,378 tons) of junk hurtle around the Earth at speeds of up to 17,500 mph, threatening functioning spacecraft, according to a statement from the University of Surrey….

[T]hese same means of capturing debris could easily be used to destroy or otherwise interfere with functional orbital assets [i.e, a functional satellite], most of which are not equipped with a rapid means of evasion or any other form of defense. To a harpoon, net, or drag sail, there is little difference between an out of control hunk of Soviet era rocket and an operational communications or reconnaissance satellite.

Excerpts from BY ALEX HOLLINGS, SpaceX delivers prototype space junk collector to the ISS, but the experiment has serious defense implications, SOFREP.com, Apr. 6, 2018;

This Space Junk Removal Experiment Will Harpoon & Net Debris in Orbit, Space.com, Apr. 6, 2018

A Vacuum Cleaner for Space

A Singapore-based venture company aspiring to enter the space business unveiled a life-sized model of a satellite that would retrieve space debris, with which the company plans to conduct a test run in orbit in 2019 and to make commercially viable by 2020.  “Space is filled with trash, and if things continue as they have, space exploration will no longer be sustainable. …

Most orbital debris is old satellites and satellite components. Around 750,000 pieces of space debris at least 1 centimeter in diameter are said to be in near-Earth orbit, and are interfering with countries’ and companies’ efforts to place new satellites. Astroscale’s debris retrieval satellite closes in on dead satellites, and uses magnets to draw them in. The device then enters the atmosphere, bringing the out-of-commission satellite with it, and burns up on re-entry.

For example, in 2009 an out-of-commission Russian military satellite and a satellite launched by a U.S. corporation collided. The International Space Station (ISS) is frequently forced to change course or have its crew members evacuate from their posts. In 2007, China destroyed one of its own satellites with a missile, producing large volumes of orbital shrapnel and triggering international criticism.

Also in 2007, the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) drafted the Space Debris Mitigation Guidelines, which recommends that satellites that are past their usefulness promptly leave their orbits. However, satellites and satellite parts that have already become space debris have uncoordinated trajectories, and because there is no established method of retrieving such litter, various countries and companies have been searching for a solution.

The Japan Aerospace Exploration Agency (JAXA) is working on a plan to attach metallic string to space debris, through which it would pass electric currents and use the Earth’s magnetic field to slow down the debris, and then drop them into the atmosphere. Meanwhile, the RIKEN research institute announced in 2015 that it had devised a method of using high-intensity lasers to slow down “drifting” litter so that they would hurtle into the atmosphere.  Researchers both within and outside Japan have proposed various other ideas, including making space debris attach to operating satellites and catching space debris with nets.

Company to test space-debris-retrieval satellite in 2019, aim to commercialize by 2020, Mainichi Japan, July 15, 2017

How to Wipe Out Space Junk

Half a century of rocket launches has turned the space into a junkyard. Around 3,000 tonnes of empty rocket stages, defunct satellites, astronauts’ toothbrushes and flecks of paint are thought to be in orbit.

Besides being messy, such debris can be dangerous. Anything circling Earth is moving pretty quickly, so collisions between space junk and satellites can happen at closing velocities of 10km a second or more. Large bits of junk are routinely tracked by radar. The International Space Station (ISS), for instance, regularly tweaks its orbit to avoid a particularly menacing piece of litter. But at such high speeds, even a small, hard-to-follow object can do tremendous damage.

Rocket scientists have been pondering how to deal with this problem for years. But a paper just published in Acta Astronautica by Toshikazu Ebisuzaki and his colleagues at RIKEN, a big Japanese research institute, has gone further and proposed actually building a test device.

Dr Ebisuzaki’s plan involves zapping things with lasers. He proposes to point these lasers in the right direction using a telescope intended for a different job entirely. This is the Extreme Universe Space Observatory (EUSO). It is designed to be bolted on to the ISS. From that vantage point it will monitor Earth’s atmosphere, looking for showers of radiation caused by cosmic rays hitting air molecules. Dr Ebisuzaki, however, realised that the characteristics of a telescope designed for this job—namely a wide field of view and the ability to register even fleeting flashes of light—would also be well-suited for spotting small bits of debris as they whizz past the ISS.

Having identified something, the next step is to get it out of orbit—and that is where the zapping comes in… Fire a laser head-on at a piece of space debris for long enough, then, and you can slow it down to the point where its orbit will decay and it will burn up in Earth’s atmosphere.  This idea is not new. But putting lasers into orbit is tricky. Those powerful enough to do the job need lots of electricity and this is hard to deliver with the solar panels from which satellites typically draw their power. Dr Ebisuzaki proposes instead to employ a new, more efficient laser called a coherent-amplification network device, which was developed for use in high-energy physics.

He and his colleagues suggest a three-stage test. The first, with a smaller version of the EUSO and a fairly weedy laser, would serve as a proof of concept. The second would use the actual EUSO telescope and a much more potent laser. Finally, he says, the equipment could be mounted on a purpose-built satellite, from which it would be able to shoot down tens of thousands of bits of space junk every year, thus gradually sweeping the skies clean .

Orbiting debris: Char wars, Economist Apr. 25, 2015, at 75

Militarization of Japan: the Fourth Force

Japan will add a new division to its military or Self-Defense Forces in 2019, to protect equipment in orbit from space debris as well as other attacks, a source familiar with Japan-U.S. relations said, according to a report by the South China Morning Post.

Japan revised a law regarding its non-military activities in space in 2008, allowing the creation of a “space force,” which will initially be responsible for monitoring dangerous debris floating within close vicinity of the Earth, as well as protect satellites from collisions or attacks, according to the report, which added that the U.S. has been informed of the development by the Japanese Defense Ministry. There are around 3,000 fragments of space debris currently at risk of smashing into reconnaissance or communication satellites around the Earth.  Japan will assist the U.S. military with the information it obtains through this program, and looks to strengthen bilateral cooperation in space, or the “fourth battlefield,” the report said.  The “fourth force” will initially use radar and telescope facilities in the Okayama prefecture that the defense ministry acquired from the Japan Space Forum, which also owns the Spaceguard Center radar facility in Kagamino and a telescope facility in Ihara.

Units from Japan’s Air Self-Defense Force are currently being considered by the defense ministry to make up parts of the new space force. And, the Japanese ministries of defense, education, culture, sports, science and technology, along with the Japan Aerospace Exploration Agency, or JAXA, will jointly acquire the radar and telescope facilities from the Japan Space Forum, a Tokyo-based think tank that coordinates aerospace-related activities among government, industry and academia.

Japan and the U.S. have reportedly been working on a space force since 2007, when China tested its satellite destruction capabilities by launching a missile against one of its own satellites and destroyed it.  In May, at a space development cooperation meeting held in Washington, the Japanese and U.S. governments agreed to increase cooperation in using satellites for monitoring space debris, marine surveillance, and to protect one another’s space operations. Japan also pledged to share information acquired by JAXA with the U.S. Strategic Command.

Excerpts from Alroy Menezes, Japan’s ‘Space Force’ To Protect Satellites In Orbit, International Business Times, Aug. 4, 2014