Space-Weather Instruments Added To Solar-Sail Demo

By Amy Svitak
Source: Aviation Week & Space Technology

Barnes says the launch is funded by NASA through the U.S. Air Force, which contracted SpaceX to carry the Dscovr mission as part of the rocket's military launch certification process.

“They were going to this place, and we had planned on going to this place, so it's a terrific opportunity and synergy we're going to capitalize on,” says Barnes, adding that Sunjammer's launch costs comprise roughly one- third of NASA's $27-million investment in the demonstration.

Following liftoff from Cape Canaveral, the Falcon 9 is expected to jettison Dscovr, sending it to the Earth-Sun Lagrangian point, also known as L1, where it will replace ACE. Sunjammer will be jettisoned a short time later, initially deploying a small antenna and solar arrays before firing four 5-lb. hydrazine thrusters.

“These are small reaction control thrusters that big spacecraft use for orbital positioning, but we're using them for our main thrusters,” Barnes said. “The burn will take one or two minutes, but it gets us to where we mathematically can, or cannot, operate.”

If the sail deploys as expected, the booms supporting it will be “rigidized” ahead of final checkout of the spacecraft, at which point the hydrazine tank, thrusters and primary batteries will be jettisoned. In addition to deploying the 40 x 40-meter solar sail, the six-month mission will demonstrate attitude control and passive stability and trim using beam-tip vanes, and execute a navigation sequence with mission-capable accuracy.

Barnes says six months is enough to send Sunjammer close to its objective —the desired sub-L1 point 300 million km from Earth. But if all goes well, L'Garde plans to continue operating the spacecraft indefinitely.

“We have onboard solar arrays, and Sunjammer has no propellant, so until something fails, a device or a widget, there's no reason to turn it off,” he says. “We would like to experiment with a few other things, to incline ourselves up on on a radius plus or minus 20 degrees to demonstrate some more of the capabilities of the sail itself.”

During the mission, Sunjammer will fly two instruments developed by scientists at Imperial College London and Mullard Space Science Laboratory (MSSL) in Oxford. These include a magnetometer, known as Magic, and a wind analyzer, Swan—both designed to monitor different aspects of space weather to help researchers understand its influence on space-borne and ground-based systems.

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