Greenbelt, Maryland. October 2, 2014 – The Magnetospheric Multiscale (MMS) Observatory #4 underwent spin testing at the NASA Goddard Space Flight Center in Greenbelt, Maryland today. Engineers use this machine to determine the spacecraft’s center of gravity, adding counter balances as needed to ensure it spins correctly while in orbit.
All four of the MMS observatories undergo spin testing prior to launch. The MMS spacecraft are spin-stabilized with a spin rate of three revolutions per minute.
The MMS mission is a Solar Terrestrial Probes mission consisting of four identical spacecraft that will orbit around Earth through the dynamic magnetic system surrounding our planet, making three-dimensional measurements of its magnetosphere. The purpose of the mission is to study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence.
Plasma is the mix of positively and negatively charged gas particles that make up the stars, fill space, and account for an estimated 99% of the observable universe. Plasmas behave unlike anything we experience on a regular basis on Earth because they conduct electricity and travel with their own set of magnetic fields entrapped in the material. Changing magnetic fields affect the way charged particles move and vice versa, so the net effect is a complex, constantly-adjusting system sensitive to minute variations.
Under normal conditions, even in this constantly changing plasma, the magnetic field lines don’t braek or merge with other field lines, but sometimes, as two sets of field lines get close to each other in particular configurations, the plasma disconnects from the magnetic field and the entire pattern changes in a process known as magnetic reconnection.
When magnetic reconnection occurs, the amount of energy released can be formidable, hurling particles off into new directions at incredible speeds. These processes play an important role in what is known as “space weather.”
Most of what scientists currently know about the small-scale physics of magnetic reconnection comes from theoretical studies, computer models and observations of reconnection events seen on the sun. Several spacecraft, including THEMIS and Cluster, have sent back tantalizing data when they happened to witness a magnetic reconnection event in Earth’s magnetosphere, but no mission other than MMS is currently dedicated to the study of this phenomenon.
MMS will travel directly through areas near Earth known to be magnetic reconnection sites. On the sun-side of Earth, reconnection can link the sun’s magnetic field lines to Earth’s magnetic field lines, allowing material and energy from the sun to funnel into Earth’s magnetic environment. On the night side of Earth, reconnection is believed to help trigger aurora, also known as the Northern or Southern lights.
By studying how reconnection occurs near Earth, MMS will improve our understanding of how this fundamental process works elsewhere in the universe. Magnetic reconnection also occurs on the sun and is the driver of solar flares and massive eruptions of a material called coronal mass ejections. Scientists have also theorized that magnetic reconnection may be involved with a variety of astrophysical phenomena including how high-energy cosmic rays are accelerated so fast.
Understanding reconnection could even provide clues to developing a new source of efficient, clean, sustainable energy here on Earth, as magnetic reconnection can interfere with the success of fusion energy reactors.
The MMS mission will rely on its four spacecraft with identical sets of 11 instruments made of 25 sensors. The four spacecraft will fly in an adjustable pyramid formation that enables them to oberserve the 3-dimensional structure of magnetic reconnection. Four spacecraft give MMS the necessary observational perspectives to determine whether reconnection events occur in an isolated locale, everywhere within a larger region at once, or traveling across space.
Each MMS observatory is in the shape of an octagon, roughly 11 feet across and 4 feet high, and built around a central cylindrical thrust tube. The majority of the science instruments and associated electronics are mounted on the underside of the top deck. The flight control hardware in installed on the upper side of the bottom deck. Each observatory is also equipped with six long electric antennas with science sensors on the end as part of the science experiments. Primary power is supplied by eight solar array panels, with a secondary battery for energy storage and use during eclipses.
The Laboratory for Atmospheric and Space Physics (LASP) in Boulder is hosting the MMS Science Operations Center (SOC), which includes science operations planning, instrument command sequence development, and science analysis support.
Additionally, science data for all MMS measurements will be hosted at LASP and centrally disseminated to the science community. LASP Director, Dan Baker, is leading the SMART (Solving Magnetospheric Acceleration, Reconnection, and Turbulence) Science Operations Center, and LASP built several key components to the MMS FIELDS investigation instruments.
The MMS satellites are currently scheduled to launch atop a United Launch Alliance Atlas V rocket from Cape Canaveral, Florida on March 12, 2015.