Led by principal investigator Professor Andrew Yau (University of Calgary), ePOP stands for Enhanced Polar Outflow Probe and is a significant milestone for the Canadian Space Agency. The e-POP team is comprised of scientists and engineers from seven Canadian universities and three research organizations: the University of Calgary; York University; the Universities of Alberta; Athabasca; Saskatchewan; Western Ontario; and New Brunswick. The Communications Research Centre, located in Ottawa, as well as the Institute of Space and Astronautical Science of Japan and the U.S. Naval Research Laboratory are also partners in the project.
The instruments on ePOP will all help to continue investigations into the nature of heavy, cold ion outflow from the polar regions of Earth's ionosphere into the magnetosphere. These often oxygen ion rich flows come up from the ionosphere near noontime in a region known as the cusp, and represent a significant mass load for the coupled ionosphere-magnetosphere system. Understanding them is an important key to understanding the entire Earth geospace system's response to space weather variations, or changes in characteristics of the flow of the solar wind streaming outward continually from the sun's corona. This is because heavy cold ion outflows significantly change the 'stiffness' of the magnetic field lines forming the magnetosphere surrounding earth, and therefore change resonant frequencies of a common wave mode coupling geospace. The Alfven mode, named for Hannes Alfven, can be thought of as a longitudinal mode similar to plucking a string - except this time, instead of the string being one on say a musical instrument, the string is the magnetic field. More heavy mass on that string changes the frequency when it's plucked, just like using heavier gauge strings lowers their resonant frequency.
For radio physics and geospace studies, ePOP has several important instruments:
• The Coherent Electromagnetic Radiation tomography experiment
(CER) will perform radio transmission from e-POP to ground for
radio propagation and ionospheric scintillation measurements.
• The Fast Auroral Imager (FAI) will measure the large-scale auroral
emissions in the 630-1100 nm wavelength range.
• The Global Position System (GPS) receiver-based Attitude, Position,
and profiling experiment (GAP) will be used for spacecraft position
and attitude determination and for ionospheric radio occultation
• The Imaging and Rapid-scanning ion Mass spectrometer (IRM) will
measure the composition and 3-dimensional velocity distributions of
ions in the ionosphere.
• The MaGnetic Field instrument (MGF) will investigate the localization
and characterization of field-aligned currents in the high-latitude
auroral zones and polar caps.
• The Neutral Mass and velocity Spectrometer (NMS) will measure
mass composition and velocity of neutral atmospheric species.
• The Radio Receiver Instrument (RRI) will measure wave electric fields
in the 10Hz - 18MHz range, at magnitudes from 1 μV/m to 1 V/m.
These measurements will provide information about the morphology
and dynamics of ionospheric density structures, auroral wave-particle
interactions, plasma nonlinear processes created by intense high
frequency waves, and the mechanism of coherent wave backscatter.
• The Suprathermal Electron Imager (SEI) will measure the electron
energy and pitch angle distribution over the energy range of 1 to
200 eV, with particular emphasis on photoelectrons in the 1 to 50 eV
range, which are believed to play an important role in the polar wind
Cassiope has a polar, highly elliptical orbit (324 x 1500 km altitude). At MIT Haystack, we expect to have many opportunities for science using in particular the CER beacon experiment with ground receivers during overflights. These overflights will also allow us to make multipoint observations of subauroral ionospheric features through combining ePOP data with wide field ionospheric measurements using our megawatt class large aperture incoherent scatter radar system, HF backscatter radar measurements of convection using the SuperDARN array, and other orbiting satellites such as the DMSP platform.
Congratulations to all involved, and we're looking forward to a long and successful mission. You can follow the status of the mission at SpaceFlight Now's page, and more Cassiope information is at the project home page.