Just south of the Arctic Circle, a research range sits comfortably in the snowy foothills of Alaska’s White Mountains. Known for its sparse population, preponderance of auroral activity, and leagues of undeveloped natural beauty, this spot is ideal for certain kinds of research – specifically ones that roar high into the sky.
Poker Flat Research Range, owned and operated by the University of Alaska Fairbanks’ Geophysical Institute under contract with NASA’s Wallops Flight Facility, is known primarily for launching sounding rockets. These rockets – basically flying tubes of scientific instruments – soar into different levels of the atmosphere to take in situ measurements that are difficult to obtain through other methods. This month, one mission – named Dissipation – could have exciting implications for NASA’s Geospace Dynamics Constellation (GDC) mission.
With a launch window that opened on Nov. 5, the Dissipation team waited for the skies to clear and the dancing lights of the aurora to be present. They wanted to study how energy from the magnetosphere dissipates in the upper atmosphere in the forms of heat and visible light. A sky with active auroras is one of the best indicators that conditions in the ionosphere and thermosphere were just right for launch.
The engineers, scientists, and technicians built pieces of the rocket at NASA’s Wallops Flight Facility in Wallops Island, Virginia. The pieces were then shipped to Alaska to be fully assembled and calibrated for launch in the payload assembly building at Poker Flat Research Range. After assembly and calibration, the rocket was transferred to a cart and taken to the rocket assembly building, where technicians added the rocket’s solid-fuel propulsion. Then, it was wheeled out to the launch pad to be readied for the dress rehearsal.
Mehdi Benna, aeronomist and planetary scientist for the University of Maryland and NASA’s Goddard Space Flight Center, is the principal investigator for both GDC’s MoSAIC (Modular Spectrometer for Atmosphere and Ionosphere Characterization) instrument and for Dissipation, which launched an engineering model of MoSAIC into the skies above Alaska.
In an interview with the University of Alaska Fairbanks (UAF), Benna said Dissipation is particularly exciting because it is a pathfinder for MoSAIC, and will provide a focused look at some of the phenomena that GDC will study in-depth. Phenomena like Joule heating, which is a process that occurs in the atmosphere when currents from the magnetosphere drive positively-charged ions to collide with neutral gases, releasing energy in the form of heat.
According to Mehda, Dissipation “will give us an early taste of what the GDC data will look like.”
Team members drove approximately 30 miles every day from Fairbanks to Poker Flat. Since rockets at Poker are almost exclusively launched during the winter months, these drives can be treacherous – from snowy, white-out conditions to black ice to moose or elk ambling across the highways. One thing is certain, though: the views are always spectacular.
It is standard practice at Poker Flat for rockets to be encapsulated in styrofoam once assembled and brought out to the launch pad. The styrofoam insulates the rocket and protects the sensitive instruments on board from the precipitation and extreme cold that Alaskan winters tend to offer. A heating element also ensures temperatures inside the styrofoam casing stay around a balmy 65 degrees Fahrenheit.
In a sounding rocket mission, there are two main teams: the rocket team and the science team. Members of the rocket team go through their checklist of requirements, ensuring instruments are working correctly and the rocket is armed, vertical, and ready for launch, but it’s ultimately up to the science team to give the final approval for launch. For Dissipation, atmospheric activity was monitored in three locations in Alaska: Poker Flat, Venetie, and Toolik. The rocket would be launching at an 84-degree angle, shooting up to 200 miles (350 kilometers) in the sky, and eventually returning to Earth a couple hundred miles north where it would then be retrieved.
Poker Flat Research Range features a lidar (light detection and ranging) facility that can measure atmospheric conditions at various altitudes. The range uses two types of lidar systems: a green, single-beam laser for measurements of wind vs altitude by looking at Rayleigh scattering (electromagnetic radiation dispersion due to tiny, sub-wavelength particles) and a three-pronged, yellow-orange laser looking specifically at the density, movement, and temperature of sodium in the atmosphere. The lidar research team turned on its systems to collect simultaneous data of the atmosphere during Dissipation’s launch window.
Just after midnight on Nov. 11, a geomagnetic substorm caused a burst of auroral activity above all three locations the science team was monitoring. A weather balloon was launched to ensure safe wind conditions, and the countdown began from four minutes, thirty seconds!
Just outside the science operation center, people gathered on a catwalk to watch the rocket launch. They could hear the countdown from the telemetry building down the road through the radio. “T-minus ten, nine, eight, seven….” As soon as the voice on the radio hit zero, the faraway launch pad filled the hills and valley with a bright yellow glow, and the rocket was, well, rocketing into the sky. A few seconds later, the explosion of sound reached the catwalk, rumbling the chests of the onlookers. They watched the first stage of the Oriole II rocket burn out and detach, and the second stage light up half a second later. The rocket disappeared into the night sky, leaving a trail of smoke eventually swallowed by the aurora.
A sounding rocket mission isn’t over after the rocket launches, however.
Once the booster separates from the rest of the rocket, the team waits anxiously to learn if their onboard instruments deployed correctly and can gather and send data. Thankfully, Dissipation’s instruments deployed and worked beautifully, streaming real-time information indicating the rocket was, indeed, flying through a substorm. The team excitedly monitored incoming data for the duration of the flight – about 30 minutes total – from multiple screens. But tensions rose once more as the group waited for confirmation from the telemetry team that the rocket’s parachute deployed, the GPS locator was working as expected, and the payload carrying MoSAIC had landed.
A cheer erupted from the group as soon as they learned the rocket hit the ground safely: Dissipation was a success! All that was left was to retrieve MoSAIC, collect the rocket parts, and analyze the data to better understand our dynamic atmosphere.