Copyright © Françoise Herrmann
On top of overflowing landfills releasing dangerous amounts of the greenhouse gas methane, and an estimated 150 million tons of plastic polluting oceans, planet Earth also has to contend with space garbage (i.e., garbage in outer space).
Space garbage comprises more than 6000 satellites no longer in use that have been launched since 1957, and more than half a million pieces of space debris resulting from explosions and collisions, currently moving at more than 20,000 miles per hour in space. Space garbage that potentially results in what is termed the Kessler Syndrome. A syndrome where there are so many satellites or space vehicles orbiting at high (1), medium (2) or low (3) distances from the Earth, that there is no safe orbiting space left for new and functioning satellites. Having outlived their mission, space vehicles and debris pose constant risks of collision or explosion, which effectively prevent the positioning of any other functioning vehicles in their vicinity.
Even more dangerously, space debris also pose potentially serious threats to human populations and infrastructures. Space garbage poses a threat when returned uncontrolled to the Earth’s atmosphere, where it may not be completely destroyed, causing debris to potentially drop at tremendous speed on the surface of the Earth. Uncontrolled satellites, some of which contain radioactive materials on board, or highly toxic propellants, which could be dispersed in the atmosphere, over densely populated areas.
Many solutions to space garbage exist. For example, some vehicles have a reserved portion of propellant, enabling the vehicle to be repositioned on what is called a parking or cemetery orbit. A parking orbit is a high orbit of no use to space missions. However, such a solution shortens the lifecycle of a satellite, which has to use its propulsion system for relocating on a parking orbit.
In general, an estimated 10 to 15% of the total costs of a satellite are dedicated to relocation and compliance with such regulations as those set forth in the United Nations Convention on International Liability for Damage caused by Space Objects. Thus, while various patented solutions already exist for de-orbiting space objects, and/or moving them to a parking orbit, all of such solutions are expensive, requiring another space engine with its own re-ignitable thruster. Whether the solution calls for dissolving space debris, using solar radiation passing through lenses (US5120008); or sweeping away debris, after causing them to impact and attach to panels, (US4991799); or even tethering debris to relocate them (US5082211), existing solutions appear not only expensive, but hazardous.
The patented solution, which was selected as a candidate for a European Inventor Award in 2023, aims to remedy the prior art issues of cost-effectiveness and hazard, invoked in de-orbiting satellites at the end of their working life. The invention also aims to resolve a host of additional issues. Issues such as reliability and control of de-orbiting operations. Or the issue of having to launch separate devices for identifying de-orbiting candidates. Separate devices that require additional parts with complex communication and programming
Thus, the proposed invention recited in the European patent EP2734448B1, titled Device for moving or removing artificial satellites, offers a device coupled with the satellite to be moved or removed. A device that operates independently from both the satellite and remote control de-orbiting maneuvers. The device is able to effectively dispose of the satellite with which it is coupled. At the end of the satellite’s mission, the device is designed to remove the satellite from its orbit, or to de-orbit the satellite back down towards Earth. As a result, orbiting space previously occupied by the satellite is cleared, and the satellite is further prevented from interfering with other spacecraft operating in the vicinity. The invention device, coupled to the satellite, comprises: on-board means of control, means to receive and emit signals, propulsion means operatively connected to the satellite’s onboard controls, a separate electric power supply, making it independent from the satellite, means to mitigate thrust vector misalignment, and pre-launch mechanical coupling means,
The Figures 1 and 2, extracted from the patent, respectively show: a schematic representation of the types of orbits used for satellites, including arrows depicting the deorbiting method used according to the invention device, and a cross-sectional view of a first embodiment of the invention device.
In particular, the Figure 1 depicts the invention device associated with two different types of satellites 20' and 20", orbiting around a celestial body, such as the Earth 1. The satellite 20' is shown operating on a Low Earth Orbit (LEO) 2. As the arrow indicates, the satellite 20' has to be de-orbited towards the Earth’s surface within a specific special-temporal de-orbiting window. The satellite 20" is operating on a high orbit 3 (between a Medium Earth Orbit and a GeoStationary Earth Orbit). The satellite 20" would be a telecommunications or scientific satellite. As the arrow indicates, the satellite 20" would need to be de-orbited towards a higher parking orbit 4, to avoid interfering with other satellites and missions, when it has reached the end of its lifecycle.
The Figure 2 depicts a first embodiment of the invention device 10. The device 10 comprises a cylindrical metal housing 110. The housing is made of three parts: a convex or semi-spherical head portion 112, a cylindrical center portion 114, and a flat or convex terminal portion 116. The portions may be produced separately, and then joined by various ways known to the art. The device 10 also comprises propulsion means in the form of one or more solid propellant engines 212, at least one combustion chamber 214, and at least one igniter 216, for the solid propellant 212. The propulsion means also comprise at least one exhaust nozzle 218 for discharging combustion gases. The propulsion means are enclosed in a cylindrical container, also containing the charge of propellant 212. In the Figure 2 embodiment of the invention device 10, the container coincides with the housing 110 of the invention device itself.
Below, the abstract of the invention referencing the embodiments of the device (10, 20, 40 and 50) and of the means for mechanically coupling the device to a satellite (310, 320, 330, 340', 340", 350, 360), respectively depicted in Figures 2, 3, 13 and 15.
The present invention relates to a device (10, 20, 40, 50) for coupling with a space satellite (20', 20") before the latter is launched for the purpose of re-orbiting said satellite and/or returning it to Earth. The device comprises. means for controlling the device (10, 20, 40, 50); propulsion means operatively connected with the control means; means for receiving control signals operatively connected with the control means; means for electrically powering the device (10, 20, 40, 50); means (310, 320, 330, 340', 340", 350, 360) for mechanically coupling the device (10, 20, 40, 50) with said satellite (20', 20") before the latter is launched. The propulsion means are enabled by the control means on receipt of control signals for de- orbiting the satellite (20', 20") and transferring it to a given orbit. [Abstract of the invention taken for the same family patent WO2013011073A1]
Notes
(1) High Geostationary Earth Orbits (GEO), also called equatorial orbits, are at a distance of about 22000 miles from the Earth’s equator. Objects traveling on GSOs, orbit around the Earth at the same speed as the Earth’s sidereal rotation, which means that from Earth, geostationary objects appear as though they are not moving.
(2) Medium Earth Orbits (MEO) are at a distance of about 6200 miles from the Earth’s surface. For example, GPS satellites orbit at a distance of about 11000 miles from the Earth’s surface.
(3) The distance of Low Earth Orbits (LEO) is between 125 and 1250 miles from the Earth’s surface. Most satellites operate on low orbit, including the International Space Station. (ISS). It takes about 90 minutes for a low-orbiting object to complete an orbit.
