NASA study looks to the ionosphere to improve GPS communications
A new NASA study focusing on irregularities in Earth’s upper atmosphere may help scientists overcome disruptions in GPS communication. The findings provide an insight into the causes of the disruptive regions, and represent the first time that such observations have been made from space.
The ionosphere is a barrier of charged ions and electrons, collectively known as plasma, produced by a combination of impacting particles and solar radiation. When signals pass through the barrier, they sometimes come into contact with irregularities that distort the signal, leading to less accurate data.
The NASA observations, carried out by the Canadian Space Agency’s Cascade Smallsat and Ionospheric Polar Explorer (CASSIOPE) satellite, focused on the Northern Hemisphere. They compared turbulence in the auroral regions – narrow, oval-shaped areas outside the polar caps that are bombarded with particles from the magnetosphere – with that observed at higher latitudes, above the Arctic polar cap.
It was found that irregularities tend to be larger in the auroral region – where they were measured to be between 1 and 40 km (0.62 to 25 miles) – than at higher latitudes, where they measured between 1 and 8 km (0.62 to 5 miles).
The study surmised that the variation between the two regions can be attributed to outside factors, with the auroral regions being exposed to energetic particles from the magnetosphere, while the polar cap region is affected by solar wind particles and electric fields in interplanetary space. This is important information in understanding and mitigating the effects of the irregularities.
Given the issues they cause – from the distortion of radio telescope imagery to disruption in aircraft communications – obtaining a greater understanding of the irregularities is an important endeavor, and will help researchers to predict when and where they will occur.
One example of the usefulness of such predictive abilities relates to NASA’s Deep Space Network (DNS), which monitors the positions of spacecraft from Earth. The system is routinely affected by the ionosphere, but this could be mitigated by the findings, with the team able to measure the delay in GPS signals caused by the disruptions in ionosphere, relaying the information back to the DNS team.
"By understanding the magnitude of the interference, spacecraft navigators can subtract the distortion from the ionosphere to get more accurate spacecraft locations,” said JPL supervisor Anthony Mannucci.