As one would imagine, scooping up cosmic trash in the vacuum of space is no easy task. Three companies at the forefront of space debris removal provide insights on this unique set of challenges.
On Wednesday, January 29, 2020, all eyes were on the skies high above the city of Pittsburgh. Hundreds of miles above the Earth, two defunct satellites were barreling toward one another with about a 1-in-20 chance of colliding at nearly 33,000 miles per hour. Fortunately for us, this time around, the two satellites passed one another in the night without incident, but we're not always so lucky.
Since the launch of Sputnik in 1957, the orbit around our planet has quickly amassed quite the garbage patch. This includes spacefaring leftovers from previous launches and the cosmic graveyard that is thousands of dead satellites no longer communicating, now merely adrift in the vacuum of space. These pieces of debris range from infinitesimally small flecks of paint to objects roughly the size of a school bus whirling overhead at about 18,000 miles per hour. (For perspective sake, that's nearly seven times the speed of a speeding bullet.)
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Remember, it only takes one piece of space junk to set off a potentially catastrophic event known as Kessler Syndrome in which one collision leads to other collisions cascading until this orbital realm is left inhospitable for potentially decades. In 2009, Iridium 33, an operational US satellite, collided with Cosmos 2251, a defunct Russian satellite, high above Siberia, creating a massive debris field in the blink of an eye, each piece destined to haunt this realm for years to come.
As clutter increases, so too does the risk of initiating that first fateful domino setting in motion a catastrophic chain reaction. Needless to say, there are several highly complex technological achievements that need to happen to successfully deorbit this debris, each with its own set of difficulties and virtually zero margin for error. Simply put, there's no shortage of factors at play.
"In the technical terms, the most challenging part about collecting debris in space and deorbiting them, is the rendezvous with the space debris orbiting at 7Km/s, the capture of the debris in a frictionless microgravity environment, and its de-tumbling, " said ClearSpace CEO and cofounder Luc Piguet.
ClearSpace is one of several companies looking to take on this daunting task. The European Space Agency has commissioned what it hopes will be the first successful mission to remove a piece of debris from orbit, ClearSpace-1. With a launch scheduled for 2025, the mission will use a "chaser" craft to capture the Vespa (VEga Secondary Payload Adapter), a portion of an upper-stage rocket left in space following a 2013 ESA launch. The object was selected as the initial target because it is similar in size to a small satellite, acting as an ideal test subject before attempting larger and more complex targets. ClearSpace-1 will use four onboard robotic arms to apprehend and deorbit the Vespa. Eventually, the team hopes to accomplish multiple deorbits with a single chaser craft, but the primary objective is removing objects before they extend the debris field.
"The main focus is on complete satellites and large objects before they fragment due to collisions or explosions. A collision generates a massive number of objects which spread over time in many orbits around Earth, spreading very far from each other, dramatically increasing the costs of removal," said Piguet.
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Raytheon SpaDE System
Raytheon BBN Technologies is focusing its effort on space debris removal around an entirely different set of deorbiting solutions. As part of the Space Debris Elimination (SpaDE) system, the company is harnessing the inherent energy of our atmosphere to alter the path of debris in orbit. The SpaDE system directs bursts of upper atmospheric gasses directly into the trajectory of a particular piece of debris to increase drag and expedite the deorbiting process. The company believes this system has multiple comparative advantages and lacks the inherent risks associated with introducing new craft into orbit.
"With a wide cloud, the precise determination of the debris is not necessary, and the density of the cloud can be varied so that deorbit time can be controlled. Also, since we're using gases ejected from the atmosphere, this method does not introduce potential new space debris. The gas particles dissipate and settle back into the atmosphere, " said Daniel Gregory, principal investigator for Raytheon BBN Technologies.
Astroscale is another company spearheading this cleanup effort at the cusp of the final frontier with the Japan Aerospace Exploration Agency (JAXA). Earlier this year, Astroscale was selected as a commercial partner by JAXA for the Commercial Removal of Debris Demonstration project (CRD2). As part of the initial phase, Astroscale will utilize data acquired from an upcoming launch to gain a better understanding of the existing debris field. Currently, the company is approaching debris clean-up in two separate fields: active debris removal and end-of-life services.
As part of the future system, Astroscale envisions satellite manufacturers including a small ferromagnetic docking plate along the exterior of these spacecraft. At the end of a satellite's operational life or in the event of failure, an Astroscale service satellite can then rendezvous and dock with a craft using a robotic arm with a magnetic plate at the end. Standardized universal manufacturing procedures is one thing; removing a grab bag of existing debris of all shapes and sizes is another. Astroscale is also developing guidance, navigation, and control (GNC) software to ensure successful and reliable servicing systems in the future.
Earth orbit: A vital collective resource
These sophisticated orbiting craft whirling overhead touch every aspect of our day-to-day lives here on Earth, from casually scrolling through our Instagram feed to using GPS systems to find our way. These vital instruments are also crucial for lesser-known purposes, such as tracking wildfires and even monitoring illegal fishing. That said, keeping this realm secure is crucial for all Earthlings.
"Earth's orbits seem distant and unrelated to life on Earth, but the fact is that our daily lives and our futures are directly connected to maintaining sustainability in space. Even though we cannot see or touch our orbital environment, it is still a natural resource, very similar to that of our forests, oceans, and rivers, and is an essential part of our global ecosystem," said Astroscale COO Chris Blackerby.
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