Paul Bernhardt, University of Alaska Fairbanks; Lauchie Scott, Defense R&D Canada; Andrew Howarth, University of Calgary
Keywords: Plasma Waves, Space Debris
Abstract:
Research scientists in the United States and Canada have demonstrated a new way to locate pieces of space debris that threaten spacecraft and satellites in orbit. Space debris, or space junk, consists of leftovers from human-made objects – such as discarded launch vehicles or parts of a spacecraft – typically trapped in orbit around the Earth. Currently, NASA tracks over 27,000 such objects in low Earth orbit. The European Space Agency (ESA) estimates that the total mass of all space debris in Earth’s orbit is close to 22 million pounds (10 million kilograms). The number of debris that are too small to be tracked, yet large enough to cause severe damage upon impact, is in the millions. Since both space debris and active spacecraft travel at tremendous speeds of about 25,000 kilometers per hour, an impact of even a tiny piece of orbital debris with a spacecraft could create significant issues.
Traditionally, space debris are detected with satellite and ground sensors that use optics and ranging radars. These methods, however, cannot detect many smaller debris. Scientists from the University of Alaska and the University of Calgary have demonstrated a novel technique for locating space debris by measuring the electric fields that surround them while in motion. This new technique, called Space Object identification by in situ Measurements of Orbit-Driven Waves (SOIMOW), relies on creation of plasma oscillations as charged space debris move through space.
The Earth is surrounded by the ionosphere – a plasma layer with thermal ions and electrons. All satellites move through this plasma at speeds greater than the speed of sound. Both spacecraft and space debris become electrically charged as they are bombarded by solar photons and electrons from the plasma environment. Hypersonic charged objects can stimulate a wide range of plasma waves as they travel through the ionosphere, crossing the Earth’s magnetic field lines.
The Radio Receiver Instrument (RRI) on the Canadian SWARM-E satellite has been attempting to detect plasma waves around orbital debris using direct measurements at a point of interest. The RRI observations seem to show magnetohydrodynamic (MHD) waves and electrostatic waves as far as 90 km away from the space object producing them. MHD waves are produced by “striking” magnetic field lines, much like plucking a guitar string. Electrostatic waves are disturbances in the plasma that are caused by oscillating charged particles. The peak of this enhanced signal is found at the closest approach between the RRI detector and the target object. The cloud of enhanced plasma-wave noise lasts for about 20 seconds and is interpreted as spacecraft-driven turbulence comprised of a mixture of different kinds of plasma waves.
The challenge is to convert these newly discovered waves into EM modes that propagate long distances to be recorded by remote satellites or even on the Earth. Accurate determination of source locations would use the angular spread and time of arrival recorded from multiple receivers. Processed data may yield an image of the space debris traveling across the radio sky. The SOIMOW team is conducting experiments to determine if stimulated scatter from the UAF HAARP high power, ground-based transmitter can be employed to observe the trajectories of satellites and space debris.
Date of Conference: September 19-22, 2023
Track: Atmospherics/Space Weather