IMPALAS (Investigation of MagnetoPause Activity using Longitudinally-Aligned Satellites)
The Dayside Magnetopause
The magnetopause is the boundary that separates the solar and terrestrial plasma regimes. Its shape approximates a parabaloid of revolution, with the nose lying around 10 Earth radii upstream (in the direction of the Sun) from the Earth. It is a key boundary in the near-Earth space environment since all the coupling processes that ultimately control magnetospheric dynamics occur there - thus it is a key boundary for defining the influence of ‘space weather’ on the Earth. It is also the site of some fundamental plasma processes (e.g. magnetic reconnection, particle acceleration, boundary wave generation). The terrestrial magnetopause can provide a readily accessible analogue to other, more distant, space and astrophysical plasma boundaries, such as the magnetopause of other planets, the heliopause and boundaries between Stellar/Galactic spheres of influence.
What is IMPALAS?
IMPALAS is a developing mission concept aimed at obtaining data that will reveal the global-scale dynamics of the terrestrial magnetopause. The mission would consist of 3 spacecraft placed in orbits that would allow the spacecraft to skim across the dayside magnetopause every 2 days, while remaining in a north-south alignment with about 5 Earth radii separation. This configuration means the spacecraft remain in magnetic conjunction at and within the magnetopasue boundary (i.e. they are connected by the same terrestrial magnetic field line), and thus will make multi-point observations of magnetopause dynamics and observe boundary phenomena as they propagate over these distances.
What science questions will be answered by the mission?
Suitably instrumented spacecraft in the orbit configuration described above will be able to address many unanswered questions in magnetospheric and space plasma physics. Examples of questions that will be closed using the IMPALAS dataset include:
- What is the location of the MP reconnection site for given conditions?
- What is the importance of Flux Transfer Events (FTEs) in global dynamics of the magnetosphere?
- How do boundary waves evolve as they propagate across the magnetopause?
- Which mechanisms form boundary layers at the MP and how do they vary or evolve with position?
- How do disturbances, discontinuities and waves propagate within the magneto-sheath and how and where can they impact the MP?
- How do MP disturbances propagate along field lines and into the ionosphere?
ESA's Cosmic Vision 2015-2025
A proposal for IMPALAS was developed for submission to ESA's
2010 M-class mission call and was submitted in December 2010. Unfortunately the proposal was not selected for further study on this occassion.
Successful proposals are listed on the ESA website.
The editor of Experimental Astronomy
has invited proposers to the 2010 M-Class mission call to submit papers
their mission ideas for a special issue of the journal. The submitted
version of the IMPALAS paper (31 March, 2011) is currently under
Who are the Team?
The IMPALAS project was led by Prof. Chris Owen from the Mullard Space Science Laboratory
with support from scientists in:
- United Kingdom
- United States of America
We welcome all feedback, comments and suggestions from the UK, European and world-wide community. Please register here to show your interest in this exciting mission.
2 June 2011
cjo [at] mssl.ucl.ac.uk