Space Debris removal using....Space Debris-fed Spacecraft

Out of the 34,000 Space junks mapped bigger than 10 cm in size, there are millions of smaller debris powerful enough to damage a whole 5 Ton Telecom satellite. This number is destined to grow with the lower reliability of micro-nano-pico satellites and its increasing number to be sent to orbits from LEO to GEO in the next few years.

New Constellations made up of CubeSat in orbits higher than 1000 km, as the majority are, will take years to drop into the atmosphere. Some space junks result from collisions or anti-satellite tests in orbit. Overall, across all satellites, hundreds of collision avoidance maneuvers are performed every year, including by the International Space Station (ISS), where astronauts live.

Removing large Space debris such as a whole satellite as the Swiss Company ClearSpace SA intends to do in a €87M contract signed by ESA by capture and moving it into the atmosphere is expensive (delta-V loss) and hardly applicable to thousands of dead satellites or small junk.

Before the Kessler syndrome prevails, a scenario in which if there is too much space junk in orbit, it could result in a chain reaction where more and more objects collide and create new space junk in the process, to the point where Earth's orbit became unusable, something has to be done.

Using Space Debris to feed as propellant a Spacecraft

This is the idea proposed by SHIPinSPACE, a UK newSpace Startup. SiS has created a new architecture called "DefeS" or Space Debris-fed Spacecraft.

The concept is shown in the next figures. A large 4 m diameter Spacecraft, powered by extensible 20-50 kW (TBC) ultrathin solar cells film arrays can deploy 2 radar antennae used to track and search Space junks using mapped information and AI. The Spacecraft powers an ion-thruster of some sort capable to assure a long-lasting mission.

Once the Space debris is localized the inside cover of the incinerator chamber is opened and the junk can get in and the lid is closed. Inside the burning chamber, the junk is tracked using i.e. Lidar technology and vaporized by means of 4 robotic-arm-driven high-pulse fiber lasers with a power density and focal size large enough to sublimate Al alloy, steel, ceramics, and by thermal conduction, softer materials such as plastic. The sublimated vapors are then channeled through a piping system that can provide, using a turbo-compressor, direct discharge to vacuum, then thrust, or supply a large tank to be used as fuel for an ion-thruster.

The idea is then to use Space debris to create new propellant used to track other Space debris. The advantage is not to lose delta-V bringing into the atmosphere or a graveyard orbit but capture and burn them inside a laboratory-made S/C and provide propellant thrust in a virtuous loop. The concept is that anything sent to orbit should be exploited at 100%, including Space debris.

The debris annihilation is the condition to not lose delta-V and because this is how you can measure the efficiency of a Spacecraft the "DefeS" architecture is by far the most advanced Space Debris Removal system ever and the only one that can prove to be economically sustainable. "DefeS" can do more: it creates new propellant to produce other delta-V.

The S/C just avoids to use capture means as not necessary and can burn debris from a few mm up to 3 m size, making it one of the most versatile concepts ever seen and, more importantly, assuring a credible economic plan for removing a consistent portion of debris thanks to a sustainable propellant usage with any S/C able to operate in one critical orbit plane.

Safe operations and delta-V advantage

Using a laser to sublimate Space debris is not a new idea but the way herein proposed is new. What is new is to create a laboratory inside the Spacecraft where the laser can be used safely without harming anything outside the vacuum Space. This is a point that had raised a lot of discussions and concerns among Space Users, the way a powerful laser is used on-orbit should be in fact limited to a very safe operation like the one proposed inside the Spacecraft as an internal laboratory where if something goes wrong the damage is confined to the walls of the burning chamber.

Also, junk capture is not made by any means other than freely getting inside the burning chamber. This avoids the development of any grabbing system. The pressurized capability of the burning chamber is a guarantee of safe operations inside it.

The on-going Space debris removal concept consists to either grab a dead satellite and bring it to the atmosphere to be burned or send it to a graveyard orbit, all these operations need delta-V that is lost and is to be recovered in case more operations have to be done. The SHIPinSPACE idea here proposed doesn't lose any delta-V and the burning fumes are recovered as a propellant to get to the next debris in a virtuous loop. This business model is sustainable and infinitely much more cost-effective.

Operating on bulky Launcher stages

Though laser operation is safer when contained inside the vessel its operability outside the vessel may exceptionally be applied when a bulky rocket stage is encountered. This kind of bulky debris has normally angular momentum and are difficult to align even supposing to have a Spacecraft of its size. It is however possible to align with its CoG and its trajectory in such as way laser pointed at a few m from it would not determine a safety risk (if monitored by camera remotely on ground). This way the trajectory of a high-risk collision debris can be modified without the need to annihilate it.

A Project funded by Space Agencies and private Space Companies

A newSpace Startup can lead this Project but it is clear that the development budget should be provided by all International Space Agencies such as NASA, ESA, ROSCOSMOS, CNSA, JAXA, and private Space Companies that have all interest to reduce the Space debris risks to safely operate their business. NASA and ROSCOSMOS particularly should provide a good portion of the funding proportionally to the Space junk that have created along their long-lasting Space activities.

Though the idea can be simple, its accomplishment isn't. Artificial Intelligence (AI) must drive most part of the operations if continuous debris removal is wanted. This means that the Spacecraft must be able to get updated about debris mapping and use its tracking subsystem to drive the ion-thruster or burning fumes providing thrust in such a way to get to the next debris in an autonomous way.

This must be a global endeavor. It has been reckoned that building as many as 10 Spacecraft of this size could drop the number of large size Space debris by 30% in 10 years' time, a figure considered unthinkable so far.