A mission studying Earth’s magnetic field by
flying four identical spacecraft is headed into new territory.
The Magnetospheric Multiscale mission, or MMS, has been studying the magnetic field on the
side of Earth facing the sun, the day side – but now we’re focusing on
something else. On February 9, MMS started the three-month-long process of shifting to a new orbit.
One key thing MMS studies is magnetic reconnection – a
process that occurs
when magnetic fields
collide and re-align explosively into
new positions. The
new orbit will
allow MMS to study reconnection on
side of the
Earth, farther from
on the night side of Earth
is thought to
be responsible for
causing the northern
and southern lights.
To study the interesting regions of Earth’s magnetic field on the
night side, the four MMS spacecraft are being boosted into an orbit that takes
them farther from Earth than ever before. Once it
reaches its final
orbit, MMS will
shatter its previous Guinness
World Record for
highest altitude fix
of a GPS.
To save on fuel, the orbit is slowly adjusted over many weeks. The boost to take each spacecraft to its final orbit will happen during the first week of April.
On April 19, each spacecraft will be boosted again
to raise its closest approach to Earth, called perigee. Without
this step, the spacecraft would
be way too close for
comfort – and
would actually reenter Earth’s
The four MMS spacecraft usually fly really close
together – only four miles between them – in a special pyramid formation called a tetrahedral, which allows us to examine the magnetic environment in three dimensions.
orbit adjustments, the pyramid shape is broken up to make sure the spacecraft
have plenty of room to maneuver. Once
MMS reaches its
new orbit in
May, the spacecraft will
be realigned into
their tetrahedral formation
and ready to
do more 3D magnetic science.