A series of 11 sounding rocket flights from two remote locations in the Arctic circle will help unlock the secrets of the processes behind the Northern Lights.

An international team of researchers are venturing to the high Arctic to explore Earth's magnetosphere like never before.

The Grand Challenge Initiative – Cusp will include 11 sub-orbital sounding rockets launched from two Norwegian sites in 2018 and 2019: Andøya Space Center on an island off the Norwegian coast and Svalbard Rocket Range in the Svalbard Islands, part of Norway located in the Arctic Ocean. Several missions will include simultaneous launches from both two sites to obtain multi-dimensional information.

The two-year initiative combines missions fielded by Canada, Norway, the Japanese Aerospace Exploration Agency (JAXA), NASA, and other countries. The 11 rockets are part of eight overall missions participating in the project.

The Auroral Cusp

Earth's poles offer scientists a unique environment to study the electrically charged solar wind's interaction with our planet's magnetic field. The auroral cusp above the poles is where the magnetic field dips inward, enabling charged particles to impact Earth's atmosphere. This high-energy clash heats the upper atmosphere by hundreds of degrees, causing it to inflate and driving fierce winds within it.

“During the polar night mid-winter in December and January months, when seven of the missions will be conducted, it is dark all day in Svalbard. The cusp is then visible to the naked eye,” says Jøran Moen (University of Oslo).

Studying the auroral cusp is crucial to understanding how interactions in this region affect communication and navigation near the poles. Military and intercontinental passenger flights all transit this region, as do with astronauts in low-Earth orbit and polar-orbiting satellites. The upper atmosphere's inflation also drags on satellites in low-Earth orbit, speeding up their reentry.

Earth is unique among the terrestrial planets, as it's the only rocky planet in our solar system with a robust magnetic field and therefore an auroral cusp. On Venus or Mars, for example, the solar wind hits the upper atmosphere straight on. Yet Venus, which has no magnetic field at all, shrouds itself in a thick atmosphere, while Mars, which hosts weak pockets of magnetic field, has lost most of its atmosphere over time. Understanding the flow of atoms in response to the solar wind can help us understand these differences.

This project also comes during a fascinating time to study the Sun, as we're heading towards solar minimum, a low point in solar activity that's expected to arrive in 2019-2020.

NASA has two missions participating in the Grand Challenge: AZURE (the Auroral Zone Upwelling Rocket Experiment) and VISIONS-2 (the Visualizing Ion Outflow via Neutral Atom Sensing experiment)

Unlocking Secrets of the Northern Lights

The launch window for the AZURE mission runs from March 3rd to March 19th. AZURE will analyze the flow of charged particles through the ionosphere on its brief suborbital flight, specifically targeting the radio-reflective E region 56 to 93 miles above the Earth's surface and the F region above it, which extends out to about 310 miles.

The Kármán Line — the international border marking the edge of space — starts at 100 km (62 miles) up. The twin AZURE rockets will deploy chemical tracers composed of trimethyl aluminum and a strontium/barium mixture, enabling tracking stations back on the ground to document the vertical and horizontal flow of particles through the ionosphere's E and F layers. Conditions have to be just right and skies clear for the ground stations to see the chemical tracer release. NASA has carried out similar light show experiments from the Wallops Island launch facility on the Virginia coast.

VISIONS-2 will launch in December 2018, a followup to the first VISIONS launch that was carried out in 2013. VISIONS-2 will study how active aurora accelerate oxygen atoms, slingshotting them into the magnetosphere at 80 kilometers per second. These oxygen ions "can affect the rate at which solar-wind energy is transferred to the magnetosphere, and the rate and details of how this stored energy is released to produce aurora," says Principal Investigator Doug Rowland (NASA Goddard).

It'll be interesting to see what these missions turn up, as researchers continue to probe the secrets of near space.