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Exective summary

The Science of SCOPE

The SCOPE mission strategy

SCOPE in the Roadmap

SCOPE and the simulation studies

Link to Cross-Scale (ESA)

Overview

Large fraction of the universe is filled by gas in the plasma state. This implies that the magnetic field would be playing significant role in gas dynamics of the Universe and there indeed are growing interests in the magnetic effects in astrophysical situations such as accretion disks. The Plasma Universe can be characterized by high-energy, large scale dynamic phenomena, and it is these active and explosive features that fascinate us.

The earth's magnetosphere is also a typical piece of the Plasma Universe. The region is formed by the interaction between the solar wind and the planet's intrinsic magnetic field. The solar wind is a stream of ionized gas from the sun and interacts with the intrinsic magnetic field of the planet. Since the solar wind is super-sonic, the bow shock is formed in the front side of the magnetosphere. The boundary that separates the shocked solar wind from the region occupied by the earth's magnetic field (magnetosphere) is a velocity shear layer, a current layer, as well as a density gradient layer, that is, full of potential to behave dynamically. In the night side of the magnetosphere, the field lines are highly stretched anti-sunward to form a current sheet across which the magnetic polarity reverses. The anti-parallel field lines are often subject to the process called “magnetic reconnection” via which energy stored as the magnetic energy is released explosively to the plasma thermal and kinetic energies.

Shocks, boundary layers, and magnetic reconnection are ubiquitous in the Plasma Universe.

image largeimage small The near-earth space as a natural laboratory for space plasma physics. The region contains the three most important and fundamental processes of shock, reconnection and turbulence. The SCOPE formation (orbit: 10Re x 25 Re) will fly through the regions which host these processes and make simultaneous multi-scale in-situ observations. The data-based solid step forward in quantifying these processes is crucial for our fundamental understanding of the Plasma Universe.
On the other hand, the magnetosphere is the only place where detailed in-situ observations of these physical processes can be obtained. The solar corona is another piece of the Plasma Universe. Solar observations do provide us with nice graphical presentation of explosive phenomena in the solar corona, in which magnetic reconnection is playing a crucial role. It is, however, only in the magnetosphere that detailed in-situ data of the phenomena can be obtained. In trying to construct the true understanding of the Plasma Universe, detailed in-situ observations are not only better but are essential. The reason for this is that the plasma gas filling the plasma universe is in a state that is beyond our common sense. Unlike the ordinary gas that surrounds us, space plasmas are mostly in “collisionless” state, where constituent particles do not collide with each other but interact with each other solely via electromagnetic fields. Explosive phenomena occur in the Plasma Universe because usual relaxation processes are absent and the dissipation processes that trigger them show anomalous behaviors. All these fascinating aspects of space plasma dynamics have their roots in this collisionless-ness of the plasmas. If we really are to understand the behavior of space plasmas, we would ultimately have to have the way of description with kinetic effects fully taken into account. Observational data that directly supports effort of this kind is particle data (velocity space distribution function data) obtained in-situ at the site of the phenomena.
image largeimage small The science instruments onboard the SCOPE mission. The mothership is characterized by its full-scale suite of plasma instruments: 10 msec electron detection, full coverage over the energy range of interest and the wave-particle correlator. The near-daughter will assist the mothership via electromagnetic field measurements in the close neighborhood. It also performs very accurate measurements of the north-south component of the DC electric field, by pointing the spin axis toward the sun. Far-daughters are more or less nominal spacecraft of today that can resolve ion-scale dynamics.
Electric and magnetic field data are also essential in understanding the dynamics of the particles. In any case it is only in the magnetosphere that the data of these kinds can be obtained.

Our interest in the space plasma dynamics is often biased towards large scale (MHD-scale) phenomena. In a dynamic situation, however, the well-known MHD approximation is not good enough. There is energy input from a parent MHD-scale dynamics to smaller-scale dynamics at sub-MHD (ion and electron) scales. The sub-MHD dynamics often have substantial kick-back to the parent large-scale dynamics. In other words, the true understanding of what we are attracted to comes only when the dynamical coupling among the scales, from the bottom of electron-kinetic up to MHD-scale, is fully appreciated. Equipped with the new instruments that enable us to inspect magnetospheric dynamics with this new perspective, anywhere in the dynamic magnetosphere becomes an untouched region showing us wonders and providing us with new findings of collisionless plasma physics. With these new data-based inputs we will be able to step forward and to build a truly fundamental understanding of the magnetospheric dynamics. Then we will go on to contribute in establishing the new framework to describe the Plasma Universe.


PDF SCOPE.pdf

A paper describing the SCOPE mission: M. Fujimoto, Y. Tsuda, Y. Saito, I. Shinohara, T. Takashima, A. Matsuoka, H. Kojima, and Y. Kasaba, The SCOPE Mission, AIP Conf. Proc. Volume 1144, pp. 29-35 (2009).

 

It is the SCOPE misson's simultaneous multi-scale characteristics that will equip us with the new way to inspect the space plasma processes in the magnetosphere. Because of their universal implications, shocks, magnetic reconnection and turbulence will be the three prime processes to be studied.