Exective summary

The Science of SCOPE

The SCOPE mission strategy

SCOPE in the Roadmap

SCOPE and the simulation studies

Link to Cross-Scale (ESA)

Executive Summary

In order to open the new horizon of research in the space plasma physics, formation flying spacecraft of SCOPE will perform simultaneous multi-scale in-situ observations of space plasma dynamics in the earth’s magnetosphere. In SCOPE, we will combine the observations by mother-daughter spacecraft pair resolving the micro-physics (electron scale dynamics) with monitoring by the three daughter spacecraft formation of the surrounding macro/global-scale (ion/MHD-scale) dynamics. This will enable us to inspect from the cross-scale coupling point of view how the key space plasma processes develop, and that, with hands-on-data basis. Key physical processes to be studied are shocks, magnetic reconnection, and turbulence. The SCOPE mission made up of the five spacecraft will be put into the equatorial orbit with the apogee at 25Re (Re: earth radius), making the spacecraft formation to fly through the regions in the near-earth space that host the plasma processes of fundamental importance. There is lively on-going discussion on the fully world-wide international collaboration, which would certainly make the coverage over the scales of interest much better and thus make the mission success to be attained at an even higher level. The common goal shared among the international community is not only to understand the near-earth space deeper but also to make substantial contribution to our understanding of the Plasma Universe.

image largeimage small The SCOPE mission, the minimum set-up that enables simultaneous multi-scale observations. The mother-daughter spacecraft pair in the middle will resolve micro-physics down to the local electron scale while the formation flying observations by the three far-daughters will monitor the macro-scale physics that acts as the time varying boundary condition for the micro-scale physics detected by the mother-daiughter pair. The mother-ship will be a large spacecraft capable of full-set measurements that we consider now.

10 steps toward SCOPE

1. Near-earth space as the natural space plasma physics laboratory:

The near earth space, the earth’s magnetosphere, is formed as the super-sonic flow of the ionized gas from the sun, the solar wind, hits the earth’s magnetic field. It is a highly dynamics space filled with an ionized gas that, together with the electromagnetic field that the gas interacts with, shows temporal evolution of various time scales involving various spatial scales. The aurora that dances in the northern sky reflects the dynamism of the near-earth space.

2. Plasma physics in space science:

The earth’s magnetosphere is a system governed by plasma physics. There are various scenes that are of interest for space science where plasma/magnetic effects are crucial. In the broader field of space science, there is growing interest in understanding plasma effects and to have a better view of the Universe from the plasma physics oriented point of view.

3. Importance of in-situ observations:

Numerous charged particles, ions and electrons, move under the influence of electromagnetic field. The temporal development of the electromagnetic field, 6 components in total in the three-dimensional space, is in turn affected by the charged particle’s motion. One can see how complex the plasma physics governing the space can be. The earth’s magnetosphere is within the reach of science spacecraft and is the only space where in-situ observations are possible. The data obtained allow us to study the physical processes with in-depth knowledge of the particle and electromagnetic field behavior in hand, which is necessary for the fundamental understanding.

4. Magnetospheric physics in transition:

In the past, the target of the magnetospheric physics has been mostly the magnetosphere itself, that is, to know what is going on in the magnetosphere. Now that the field has matured to be fully convinced of its own merit (solid build-on process of quantitative understandings of space plasma phenomena on the basis of high quality in-situ observations), and now that we, through crossover with the neighboring fields, more and more realize that there are various scenes in general space science where plasma/magnetic effects are crucial, we are determined to step forward. Through quantifying the plasma physical processes operative in the magnetosphere, we will contribute to the fundamental understanding of the Plasma Universe.

5. Next generation observations:

We are now convinced that the attractive aspect of space plasma physics lies in its multi-scale nature. Temporal development of the system involves various spatial scales separated by more than three orders of magnitude (smallest at the electron scale of ~10km, largest at the global scale of ~100,000km). These processes of vastly separated scales are in fact coupled together to trigger and sustain a dynamic phenomenon as a whole. We are now convinced that understanding the cross-scale coupling is the crucial step in the Plasma Universe theme. Magnetospheric observations have developed from single-spacecraft era to formation flying days. Magnetospheric observations have developed from morphological description at MHD-scale to physics oriented approach to ion- and electron-scales. The next generation observation scheme must be able to capture the multi-scale nature.

6. Simultaneous multi-scale observations:

If one uses an analogy of imaging, simultaneous multi-scale observation is to have high resolution pixels and a wide field of view at the same time. It is to resolve electron scale physics in the key region embedded in larger scale (ion- and MHD-scale) dynamics.

image largeimage small Cross-scale coupling in space plasmas. Because space plasmas consist of ions and electrons, whose mass are desperately separated by a factor of 1836, and because the numerous particles interact only via electro-magnetic field without collisional relaxation, space plasma dynamics is full of modes at various temporal/spatial scales. The MagnetoHydroDynamics (MHD) is a useful approximation that gives a rough sketch of what's going on at large scales. To answer all the questions of the modern space plasma physics, and to fully appreciate the wonders of space plasmas, however, we need to step beyond MHD and to build a new framework of describing the system. Cross-scale coupling, the notion that all the scales (MHD ~ ion ~ ion/electron hybrid ~ electron scales) are coupled dynamically in most of the active events that we are attracted to, is the key word in the new paradigm and simultaneous multi-scale observations is one of the agents that support the building process of the new framework.
The larger scale dynamics determine the boundary condition for the key region and the micro-physics therein. In turn, the key micro-physics have impact on the larger scale dynamics (This actually is the very reason why it is called the key process in the embedded key region.). In SCOPE, simultaneous multi-scale observations are performed by a mother-daughter pair spacecraft zooming into the electron scale and a three-spacecraft formation surrounding the mother-daughter pair and thus monitoring the large-scale dynamics encompassing the key region observed by the mother-daughter pair.

7. Target space plasma processes:

If one is to give three most important space plasma processes that have universal implications, they are shocks, magnetic reconnection and turbulence. Indeed, all of these processes require multi-scale analysis for their fundamental understandings. With the SCOPE orbit, the regions hosting these three processes are visited and the three processes will be studied with in-situ data of simultaneous multi-scale characteristics.

8. SCOPE spacecraft and instruments onboard:

SCOPE is made up of a mother-daughter pair and a three-spacecraft formation. The mother spacecraft is a large spacecraft and has the capability to perform the cutting-edge plasma and field measurements. The instruments that are under development, such as, the fast electron spectrum analyzer (FESA), the medium energy (10-200 keV) particle detector (MEP) and the wave-particle correlator (WPC), will be onboard the mother spacecraft. These will enable us to see how the particles are accelerated in a dynamic process and how the wave-particle interaction proceeds at the electron scale. The daughter will have its spin axis pointing toward the sun so that, coupled with the mother, precise three-component DC electric field measurements will be made. The three-spacecraft formation consists of normal spacecraft of the current generation that is capable of observing ion- and MHD-scale dynamics.

9. Space engineering aspect of SCOPE:

To enable the high-quality observations that fully utilizes the formation flying capability, SCOPE will be equipped with several newly developed engineering elements such as, spin-axis antenna with inflatable extension mechanism, inter-spacecraft communication hardware that is capable of data transmission, time synchronization and localization and large volume onboard data storage. The spacecraft will be brought to the final orbit by a thruster module. This module and the deployment sequence itself are the new challenges to our engineering colleagues.

10. International collaboration:

The mother-daughter pair of SCOPE will be provided by JAXA while its three spacecraft surrounding the mother-daughter pair will be provided by Canada CSA. In planning SCOPE, because of the obvious scientific merit, joint flight with ESA Cross-Scale is the first priority issue. Indeed the Cross-Scale Science Study Team has Japanese and Canadian members from the SCOPE team. With the common science goal being shared, there is no obstacle foreseeable in the constructive collaboration. There is strong interest and a concrete plan (ROY) shown by Russian IKI to participate in this collaboration scheme. The JAXA’s H-2A launcher has a spare capability of bringing more than 1000kg to the SCOPE orbit, implying a launch possibility for our other partners. Members of the US community are highly interested in utilizing this opportunity.