The Local Ionospheric measurements Satellite (LionSat)
is a “sciencecraft” with science experiments and bus
fully integrated. LionSat is a spinner that will “roll
along” the orbit with the spin axis perpendicular to the orbit plane. It will
explore the ram/wake structure with the spin axis perpendicular to the orbit
plane. It will explore the ram/wake structure of a small spacecraft via plasma
probes placed on the outside of the spacecraft going in and out of the wake as
it “rolls” along the orbit. LionSat will obtain
ambient measurements of the undisturbed plasma environment via two probes
mounted on booms deployed from the endcaps and
correlate them to the ram/wake measurements. These probes will also operate in
different modes to investigate a broad range of geophysical conditions that
occur on various time and spatial scales. The plasma measurements of the local
ambient as well as ram/wake plasma environments via a novel hybrid plasma probe
address ionospheric measurements and effects and
represent an advanced science instrument. The LionSat
spacecraft is initially spun-up, and its spin is maintained by a pair of RF ion
microthrusters. LionSat
will measure the spin-up rate and its stability once the operational roll rate
is obtained. The LionSat team will develop and test
optimal thrusting methods to maintain stability. The miniature RF ion thruster
represents an innovative spacecraft propulsion technology.
A summer research
experience on the LionSat project would typically
involve a design effort relating to either one of the proposed science
instruments or a spacecraft subsystem. In addition, there will be testing
efforts of the proposed plasma diagnostic designs in CSSL’s
vacuum chamber. The Communications and Space Sciences Lab’s (CSSL) vacuum
chamber is a 60-cm diameter x 100-cm stainless steel cylinder roughed with a
blower and able to obtain pressures in the range of 10-7 torr though an attached cryopump.
The plasma is generated by an Electric Propulsion Lab (EPL) low energy plasma
source (LEPS) System 250. The LEPS 250 system capable of providing a high flux
of low energy ions and was designed for volume plasma generation. The plasma
environment is close to that found in the ionosphere. It is able to run on Xe, Ar, Kr, Ne,
or N2, and provides ions with 2-20 eV
energy and electron energies < 1 eV. The plasma
environment is measured with a LP system that consists of a metallic probe
attached to a source electrometer, which when swept in voltage yields the
classic I-V characteristic curve.