Since the 1960s, NASA and other space agencies have been sending more and more things into orbit. Between the depleted stages of the rockets, the spent impellers and the satellites that have been inactivated since then, there has been no shortage of artificial objects floating there. Over time, this has created the important (and growing) problem of space debris, which poses a serious threat to the International Space Station (ISS), active satellites and spacecraft.
While NASA and other space agencies regularly monitor larger pieces of debris, ranging from 5 cm (2 inches) to 1 meter (1.09 yards) in diameter, the smaller pieces are undetectable. Combined with the frequency of these small fragments of waste, this makes objects that measure about 1 millimeter in size are a serious threat. To solve this, the ISS relies on a new instrument known as a Spatial Waste Sensor (SDS).
This calibrated impact sensor, which is mounted on the outside of the station, monitors the impacts caused by small-scale space debris. The sensor was incorporated into the ISS in September, where it will monitor the impacts over the next two or three years. This information will be used to measure and characterize the orbital debris environment and help space agencies develop additional countermeasures.
Measuring approximately 1 square meter (~ 10.76 ft²), the SDS is mounted on an external load site that faces the vector speed of the ISS. The sensor consists of a thin Kapton front layer, a polyimide film that remains stable at extreme temperatures, followed by a second layer located 15 cm (5.9 inches) behind it. This second layer of Kapton is equipped with acoustic sensors and a grid of resistive cables, followed by a protection system integrated by sensors.
This configuration allows the sensor to measure the size, speed, direction, time and energy of any small residue with which it comes into contact. While acoustic sensors measure the time and location of a penetrating impact, the grid measures changes in resistance to provide estimates of the size of the impactor. The sensors at the top also measure the hole created by an impactor, which is used to determine the speed of the impactor.
Scientists then examine these data at the White Sands Test Facility in New Mexico and at the University of Kent in the United Kingdom, where hypervelocity tests are performed under controlled conditions. As Dr. Mark Burchell, one of the co-investigators and collaborators in the SDS at the University of Kent, told Universe Today by email:
"The idea is a multi-layered device. as you pass through each one When you triangulate the signals in a layer, you get the position in that layer, so twice and the positions give a speed … If you know the speed and direction you can get the dust orbit and that can tell you if it is likely to come from a deep space (natural dust) or is in a terrestrial orbit similar to that of satellites, so it is likely to be debris, all this in real time since it is electronic. "
These data will improve safety on board the ISS by allowing scientists to control collision risks and generate more accurate estimates of how small-scale waste exists in space. As noted, the largest pieces of debris in orbit are regularly monitored. These consist of approximately 20,000 objects that are the size of a baseball, and an additional 50,000 that are the size of a marble.
However, the SDS focuses on objects that are between 50 microns and 1 millimeter in diameter, which are counted by millions. Although small, the fact that these objects move at speeds of over 28,000 km / h (17,500 mph) means that they can still cause significant damage to satellites and spacecraft. By having an idea of these objects and how their population changes in real time, NASA will be able to determine if the problem of orbital debris is getting worse.
Knowing what the waste situation is like up there is also intrinsic to finding ways to mitigate it. This will not only be useful when it comes to operations in the ISS, but in the next few years when the Space Launch System (SLS) and the Orion capsule are taken into space. As Burchell added, knowing how likely the collisions will be and what types of damage they can cause will help inform the design of the spacecraft, particularly with regard to armor
"[O] you already know the danger that you can adjust the Design future missions to protect them from impacts, or they are more persuasive when they tell satellite manufacturers that they should create less waste in the future, "he said. "Or you know if you really need to get rid of the old satellites / garbage before it breaks down and unleash Earth's orbit with small-scale waste in millimeters."
Dr. Jer Chyi Liou, in addition to being a co-investigator in the SDS, is also the Chief Scientist of NASA for Orbital Debris and the Program Manager for the Orbital Debris Program Office at the Johnson Space Center. As he explained to Universe Today by email:
"Orbital waste objects of the size of one millimeter represent the greatest penetration risk for most operational spacecraft in low Earth orbit (LEO). The SDS mission will serve two purposes: First, the SDS will collect data Second, the mission will demonstrate the capabilities of the SDS and allow NASA to seek mission opportunities to collect direct measurement data in debris from the size of one millimeter to higher LEO altitudes in the future, data that they will be necessary for a reliable impact of orbital debris, risk assessments and profitable mitigation measures to better protect future space missions in LEO. "
The results of this experiment are based on previous information obtained by the Space Shuttle program. When the ferries returned to Earth, teams of engineers inspected the hardware that suffered collisions to determine the size and speed of impact of the debris. The SDS also validates the feasibility of impact sensor technology for future missions at higher altitudes, where the risks of debris to spacecraft are greater than the altitude of the ISS.
The numbers that open the eyes in space debris