Using a method presented by academics at the University of Michigan, satellite and spacecraft operators may soon be able to identify minuscule particles of trash orbiting Earth.
“Right now, we detect space debris by looking for objects that reflect light or radar signals,” said Nilton Renno, the primary investigator from the University of Michigan team and a professor of climate and space sciences and engineering as well as aerospace engineering.
“The smaller the objects get, the harder it becomes to get sunlight or radar signals strong enough to detect them from the ground.”
Objects larger than a softball are now the sole trackable pieces of “space junk,” which accounts for less than 1% of the over 170 million pieces of trash left over from rocket launches, spacewalks, and defunct satellites.
The new technology detects particles as thin as one millimeter in diameter – about the width of a pencil lead. Renno will co-present the findings with Yun Zhang, a postdoctoral researcher in climate and space sciences and engineering, at the Second International Orbital Debris Conference on December 5.
When the cloud of charged gas and debris fragments expands, it creates lightning-like energy bursts, similar to signals produced by static sparks that appear after rubbing a freshly laundered blanket.
Mojtaba Akhavan-Tafti
The findings are part of a wider, collaborative research funded by the Intelligence Advanced Research Projects Activity’s Space Debris Identification and Tracking Program. Blue Halo, a military contractor, is leading the project, which also includes the University of Alaska Fairbanks.
Trash in space is not only unattractive; it is also dangerous. A plum-sized piece of space debris can collide with another object with the same intensity as a car wreck on the highway at a normal orbital speed of 22,000 miles per hour, potentially knocking a satellite down.
Even little pieces of debris can cause damage to spacecraft, therefore tracking them is crucial for satellites and spacecraft that must take evasive actions. The Earth’s orbit is becoming increasingly congested, making satellite protection considerably more difficult. Space debris frequently collides with one another, fragmenting bigger particles into microscopic, undetected fragments as a result.
Some experts fear that the amount of space debris could exponentially grow as individual pieces continue to collide, eventually wreaking havoc upon the infrastructure that we rely on for GPS, cell phone data, weather monitoring and more.
While potentially disastrous, collisions between space debris could prove to be the best way to track tiny space junk. When small pieces of space debris collide, they blow up into tiny fragments, some of which vaporize into a charged gas due to the heat generated by the impact.
“When the cloud of charged gas and debris fragments expands, it creates lightning-like energy bursts, similar to signals produced by static sparks that appear after rubbing a freshly laundered blanket,” said Mojtaba Akhavan-Tafti, an assistant research scientist in climate and space sciences and engineering, and a lead scientist on the project.
After this initial energy burst, charged solid pieces of debris fragments can create electric field pulses whenever they are close enough to each other, producing additional lightning-like bursts. These electric signals last for only a fraction of a second, but they could help track pieces of space debris and clouds of microscopic fragments that form when debris collides.
According to the team’s most current computer simulations, when two pieces of aluminum contact at average orbital speeds, they create an electrical burst powerful enough to be detected from the ground by a 26-meter dish equipped with a high-quality radio receiver.
More sensitive radio arrays, such as NASA’s Deep Space Network, should be able to detect the electric field pulses as well. There is still plenty to be worked out. The frequency of the electrical impulses can change depending on the speed of the contact and the material of the debris, complicating identification. To be seen, the electric signals must be greater than the background signals of the terrestrial instrument and must pass through Earth’s upper atmosphere.
The team intends to improve their approach through additional computer simulations, real-world signal measurements with NASA’s Deep Space Network, and data analysis from hypervelocity tests at the Naval Research Laboratory and NASA’s Ames Research Center.Using the lasers at the facility, the researchers can fire various types of debris at targets at various orbital speeds and evaluate the characteristics of the electric discharges produced by the hit.
If such investigations find a method to detect a wide spectrum of electrical signals created by space debris collisions, they may be able to tell not just where space debris is, but also what it looks like and what it is comprised of.
