Stunning new images captured by NASA's New Horizons are said to have shed new light on Pluto's geology, composition and atmosphere. What's more is that the spacecraft also sent back over three years worth of measurements of solar winds, providing scientists with a rare glimpse into an otherwise uncharted space environment.
Solar wind is described as the constant flow of solar particles that the sun expels into space from a region that has been visited by only a few spacecraft. New Horizons' observations of solar wind ions illustrate the strong influence that the sun has on space, extending from near-Earth effects to the boundary where the solar wind meets interstellar space.
Scientists who analyzed New Horizons' data found that particles in the solar wind had picked up an initial burst of energy, perhaps making them the seeds of extremely energetic particles known as anomalous cosmic rays.
When traveling close to Earth, these super-fast, energetic rays become a radiation hazard for astronauts. However, when they are further away and at lower energies, these rays are thought to help shape the boundary in which solar winds meet interstellar space -- a region of our solar system that Voyager 2 is currently navigating and observing.
"The Voyagers can't measure these seed particles, only the outcome," said Eric Christian, a space scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "So with New Horizons going into that region, this blank patch in the observations is being filled in with data."
As the main source of solar wind, the Sun is also a driving force in shaping the space environment. Shocks in the solar wind, for example, can create space weather such as auroras.
All in all, New Horizons' data showed that the space environment in the outer solar system has less detailed structure than space closer to Earth.
"At this distance, the scale size of discernible structures increases, since smaller structures are worn down or merge together," explained Heather Elliott, a space scientist at the Southwest Research Institute in San Antonio, Texas, and lead author on the study. This, in turn, creates fewer, larger features.
Furthermore, researchers found that the speed, density and temperature of solar wind is largely shaped by the region of the sun that it flows from. Therefore, as the sun and its different wind-producing regions rotate, patterns form.
A major part of the recent study was calibrating the data, since New Horizons is one of only a few spacecraft that have explored the space environment in the outer solar system. Not only does this work help better characterize the space environment, but it will also improve future models of how solar wind propagates throughout the solar system.
Their findings will be published in The Astrophysical Journal Supplement.
