New Horizons Observes Solar Wind's Impact on Space Environment

Space environment data collected by New Horizons over a billion miles of its journey to Pluto will play a key role in testing and improving models of the space environment throughout the solar system. This visualization is one example of such a model: It shows the simulated space environment out to Pluto a few months before New Horizons’ closest approach. Drawn over the model is the path of New Horizons up to 2015, as well as the current direction of the two Voyager spacecraft – which are currently at three or four times New Horizons’ distance from the sun. The solar wind that New Horizons encountered will reach the Voyager spacecraft about a year later. Credits: NASA's Goddard Space Flight Center Scientific Visualization Studio, the Space Weather Research Center (SWRC) and the Community-Coordinated Modeling Center (CCMC), Enlil and Dusan Odstrcil (GMU)

Despite its seemingly immense emptiness, the solar system is actually suffused with a flow of solar particles emanating from the sun.

New Horizons didn’t solely just activate to snap photographs of dwarf planet Pluto when it flew by in July 2015. As the spacecraft barreled past Jupiter in February 2007, particle instruments were activated. For more than 1 billion miles of its journey, the spacecraft took measurements of the space weather in the neighborhood of the outer planets.

NASA scientists have published New Horizons’ observations in a study appearing in The Astrophysical Journal Supplement.

The study, published today, compiles observations of solar wind from 11 to 33 astronomical units (AU). The data comes from an instrument known as the Solar Wind Around Pluto (SWAP), which is operated by the Southwest Research Institute

Solar wind and large solar events awash space with particles, fields, and ionized gas known as plasma.

“Since the sun is the source of the solar wind, events on the sun are the primary force that shape the space environment,” according to NASA. “Shocks in the solar wind—which can create space weather, such as auroras, on world with magnetic fields—are created either by fast, dense clouds of material called coronal mass ejections … or by the collision of two different-speed solar wind streams.”

These events have been observed on Earth and the solar system’s inner worlds, such as Jupiter, the Northern Lights, of which vastly outshine the Earth’s.  

While the solar patterns from the sun were not as defined as they are near inner planets’, New Horizons did observe some interesting anomalies in the outer regions.

According to The Washington Post, the spacecraft observed neutral space particles that were charged by “high-speed, ionized particles from the sun.” The subsequent speed boost made these particles four times more energetic than the sun’s particles, and twice as fast.

The researchers think these particles may be the seeds for anomalous cosmic rays, which are known to cause radiation hazards for astronauts near Earth. The rays have been observed by both Voyager spacecrafts in the outer regions of the solar system.

“The voyagers can’t measure these seed particles, only the outcome,” said NASA space scientist Eric Christian in a statement. “With New Horizons going into that region, this blank patch in the observations is being filled in with data.”  

source: http://www.rdmag.com