European SpaceCraft for the study of Atmospheric Particle Escape:

Follow-on missions

Iannis Dandouras1, Masatoshi Yamauchi2, Henri Rème1, Johan De Keyser3, Octav Marghitu4, Masafumi Hirahara5

1: IRAP, CNRS / Université de Toulouse / CNES, Toulouse, France 2: Swedish Institute of Space Physics, Kiruna, Sweden 3: Royal Belgian Institute for Space Aeronomy, Brussels, Belgium 4: Institute for Space Sciences, Bucharest-Magurele, Romania 5: ISEE, Nagoya University, Japan

Leuven, November 2018

15th European Space Weather Week - Session 9

How and at what rate is Earth slowly losing

its atmosphere to space?

What are the dominant escape mechanisms?

What is their dependence on the solar and geomagnetic activity conditions?

Neutral atmosphere expansion & escape

Ion escape

Ion outflow

Solar Max

Solar Min

Exospheric Hydrogen

Zoennchen et al., 2015

Ion energisation by EM waves, E// & Centrifugal acceleration

Engwall et al., 2008

Earth : ~1026 ions s-1

varying by a factor of > 10 as a function of activity level

Dominant heavy ion escape mechanism for Earth O+ escape energy: 10 eV Mass-independent (almost)

Ion outflow

O+ escape from the dayside open polar region and its dependence on geomagnetic activity

Plasma mantle O+ escape flux for periods of different geomagnetic conditions: the colour bar defines the average flux intensity, and the arrows represent the average O+ bulk velocity.

Slapak et al., 2017

Assuming Kp ≈ 10 four billion years ago and decreasing linearly with time, the total O+ loss becomes ~ 4.8×1017 kg, corresponding to 40% of today’s total oxygen mass in the atmosphere.

Molecular dissociation energy: N2: 945 kJ/mole (9.79 eV) O2: 497 kJ/mole (5.15 eV) H2: 436 kJ/mole (4.52 eV)

Ionisation energy: N: 1402 kJ/mole (14.53 eV) O: 1314 kJ/mole (13.62 eV) H: 1312 kJ/mole (13.60 eV)

Nitrogen Escape

Nitrogen is more difficult to dissociate (triple bond) and to ionise Escape is more difficult

The key: Study the N+ / O+ escape rate as a function of solar forcing

N+ ?

For E < 50 eV: N+ / O+ escape ratio varies from < 0.1 (quiet conditions) to ~1 (intense storms). At higher energies (50 eV - 30 keV) : absence of measurements

Fate of escaping ions as a function of magnetospheric activity level

a: Quiet conditions : direct loss down tail

c: Disturbed conditions : ion trajectories towards the inner magnetosphere

(partially re-injected, then lost through charge exchange interactions with exosphere)

Escaping heavy ions downtail: Observable how far in the distant magnetotail?

Downflowing ion observations at 146 RE i.e. ~930 000 km downtail:

Ion mass spectra Christon et al., 1994

Cold O+ beam fluxes versus the tailward distance from the Earth

Seki et al., 1998

Lunar Orbit

L2

8

Basic altitude profiles in the exosphere & upper ionosphere (500 – 2000 km).

Temperature and densities of major neutrals and ions (H, He, O, N, O2, N2, NO, and CO2).

Isotope ratios (17O/16O, 18O/16O, 15N/14N, D/H).

Their variability in space and time (+ correlation with drivers) Differential fluxes (energy - angle distributions) of the hot ions (N+, N2

+, O+, H+, and He+) in the lower magnetosphere and upper ionosphere. ⇒ Correlation with external drivers: solar EUV flux, solar wind, ionospheric / geomagnetic conditions, non-linear response during extreme events.

Space missions needed to understand and quantify the atmospheric escape mechanisms & the ion circulation / loss in the magnetosphere

What needs to be measured?

ESCAPE: “European SpaceCraft for the study of Atmospheric Particle Escape”

ESCAPE s/c: Spinning (P~20 s) ~600 km x 6.2 RE

i ~ 90°

Ring Current

Injected ~10 keV

Upwelling: ~10 eV

O+, N+

Exobase

Perigee: ~500 to 700 km altitude exobase: source of escaping populations

Apogee: ~33 000 km altitude inner magnetosphere : ion transport

Inclination: ~90° polar caps: upwelling ions

M5 mission proposal submitted to ESA in 2016

Dandouras, Yamauchi, and the ESCAPE proposal team

ESCAPE spacecraft

Main spacecraft: 2.40 m diameter x 1 m height spin stabilised: 3D particle distributions

Despun platform mast: 0.35 m diameter x 1.5 m height remote sensing instruments

~700 kg, ~450 W Thanks to PASO-CNES

UVIS & AMC DPU

MIMS

EMS

WCIMS

ESMIE

UVIS

AMC

ESCAPE: Relevance to Space Weather

1. Direct monitoring of the radiation belts Real-time monitoring of the penetrating particle fluxes through the energetic ion instrument counting rates and singles / doubles / triples counting rates

2. Atmospheric expansion monitoring during space weather events

Data for updating the models for satellite drag

3. Role of solar activity in the atmospheric composition evolution (space climatology)

Atmospheric escape rates during solar storms can be used as a proxy to understand atmospheric evolution during the very active “early Sun” (1-2 billion years ago)

ESCAPE objectives are interdisciplinary

Ion – neutral interactions

Implications for habitability:

nitrogen & oxygen are essential

elements for life

History of the Earth's atmospheric composition over a long

(geological scale) time period

Ion and neutral escape

Comparative planetary atmospheres evolution

Venus Mars

Atmospheric evolution of exoplanets

ESCAPE objectives are interdisciplinary

Ion – neutral interactions

Implications for habitability:

nitrogen & oxygen are essential

elements for life

History of the Earth's atmospheric composition over a long

(geological scale) time period

Ion and neutral escape

Comparative planetary atmospheres evolution

Venus Mars

Atmospheric evolution of exoplanets

2017: ESCAPE successfully passed the first technical and programmatic screening by ESA

2018: Proposal not selected (36 submitted proposals)

FATE mission proposal: “Far Tail Explorer”

The FATE mission aims to obtain the total flux, composition, and variability of escaping terrestrial ions from the L2 Lagrange point (Sun – Earth),

the ultimate downstream position, for different solar, solar wind and geomagnetic activity conditions.

Mission: One main spacecraft and two identical sub-spacecraft (6U cubesat), following Lissajous or Halo orbits around L2, scan the Earth's magnetotail cross-section and measure particles and fields.

The nominal operation duration: 6 months. F (flexible) ESA class mission.

Proposal (phase 1) submitted to ESA two weeks ago.

FATE mission proposal: “Far Tail Explorer”

Yamauchi, De Keyser, and the FATE proposal team

FATE mission proposal: “Far Tail Explorer”

DAEDALUS: A Low-Flying Spacecraft, for the Exploration of the Lower Thermosphere and Ionosphere

Innovative mission concept for the study of the lower thermosphere, with a main satellite in an elliptical 150 × 2000 km altitude polar orbit, performing several short (day-long) excursions down to 120 km. From there it will release instrumented cubesats whose altitude will gradually decay until they burn in the mesosphere.

The mission objective is to quantify the key electrodynamic processes that determine the structure and composition of the Upper Atmosphere (called also the "ignorosphere“), the gateway between Earth’s atmosphere space, and its response to solar and geomagnetic activity conditions. cf. 1st talk of this session, by T. Sarris

MEME-X mission : “Mechanisms of Energetic Mass Ejection - eXplorer”

T. E. Moore and the MEME-X team

Mission selected by NASA for a Phase A study

350 × 1200 km orbits

ICON mission : “Ionospheric Connection Explorer”

Instrument suite continually pointing at the Earth’s limb 575 km circular orbit at i ≈ 27° In preparation for launch

Michelson Interferometer for Global High-resolution Thermospheric

Imaging

Extreme Ultraviolet Spectrograph

Ion Velocity Meter Far Ultra Violet Imaging Spectrograph

Observing Earth and Lunar atmospheric escape

from Moon orbit

Thank you !