ARTEMIS – solar wind/ shocks Jonathan Eastwood THEMIS SWT meeting, 15 December 2007

Introduction Two or one spacecraft orbiting the moon Separations few to 15 (?) Re 60 Re from the Earth Artemis will spend more time in the solar wind than the magnetosphere Extra targets during transfer? Relevance to the SMD science plan

Most compelling thought We will get essentially continuous observations of the solar wind, at high time resolution, close to the Earth Record the passage of a complete CME, without returning to the magnetosphere every few days Data Higher data rate – 3s moments Good quality moments – s/c potential corrected (ESA and SST) 3d dc electric fields Being close to the Earth reduces problems with advecting solar wind data from L1 to Earth

Targets Solar wind transients Turbulence Shock particle acceleration

Target 1: Solar wind transients CMEs – storm driving (30? - Xinlin Li) Interplanetary shocks – needs high time resolution Reconnection events – at AGU Gosling pointed out that event statistics are limited by how fast the plasma measurements are (Wind better than ACE) Northward timing of IMF – precise timing Particle events – space weather at the moon Heliospheric current sheet, CIRs Your event here Study with one or two spacecraft

Target 2: Solar wind turbulence Correlations in a range that has not been studied before Figure from Weygand Using a pair of identical spacecraft 3d electric and magnetic fields (study whistler or kinetic alfven waves in the dissipation region – cf. Bale et al., 2007) (one spacecraft) How much pristine solar wind will Artemis observe?

Target 3: Shock particle acceleration Artemis will not make measurements of the Earth’s sub solar bow shock Serendipitous observations of rare solar wind conditions that can cause the shock to move out to 60Re Artemis will extensively measure the foreshock Two point correlations of the energetic particle and magnetic field fluctuations Test quasi-linear theories of Diffusive shock acceleration E-folding distances, magnetic field power laws, for example Cluster – Kis et al. GRL, but on a smaller baseline

Artemis + Themis Direct comparison of the upstream conditions and the magnetosphere (observed in space and on the ground) in a coherent manner Radiation belt response to interplanetary shock Killer electrons – timing of their development more precisely linked to CME passage Magnetospheric response to low beta solar wind etc

Artemis at the Moon – space weather application Space weather reports at the Moon (idea after listening to a talk at AGU on Operational Weather Needs for Exploration Class Missions by Stephen Guetersloh, JSC Space Radiation Analysis Group) Themis SST 6Mev ions, 900keV electrons From NAS report “Radiation and the international space station” “Protons of only 10 MeV energy can penetrate nearly three-quarters of the surface area of a space suit. It takes a 25-MeV proton to penetrate the most heavily shielded part, the visor. Above 30 MeV, protons can penetrate the mid-deck of the space shuttle. The 10 MeV threshold for penetrating a space suit is also the energy that forecasters at SEC monitor to watch for the onset of an SPE.” “A similar energy curve for electrons shows that 0.5 MeV particles, an energy characteristic of Highly Relativistic Electron events, can penetrate space suits. HRE events typically have high flux levels, between half a million and several million electron volts, that penetrate space suits, although they rarely have dangerous fluxes of electrons at energies that can penetrate a shuttle or station hull.” “This report focuses on solar energetic particles with energies higher than 10 MeV and outer radiation belt electrons with energies higher than 0.5 MeV. These are the energies at which protons and electrons penetrate space suits. Because they are transient and hard to predict, these populations of penetrating particles pose the greatest challenge to ISS radiation risk managers.”

Summary of the NASA Science Plan (Jan 07)