M. Yamauchi, I. Dandouras, H. Rème,

and the NITRO Proposal Team

ESWW-11, Liège, November 2014Planetary Space Weather Session

Nitrogen Ion TRacing Observatory (NITRO): Toward understanding the

Earth-Venus-Mars difference of N/O ratio

Nitrogen in Planetary Atmospheres

Venus Earth Mars Titan

~ 2.5 times as much as on Earth

3% of Patmo.Venus x 90 Patmo.Earth

75 % of the atmospheric mass

~ only 0.01% times as much as on Earth(MMars ~ 10% MEarth)

~ 1.5 times as much as on Earth

98 % of Patmo.Titan

rich in N

N < 0.01% of Earth

Venus Earth Mars

Understanding the Nitrogen distribution around Earth and the differences of N / O between the sister planets

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 much more difficult to be dissociated (triple bond) and ionised

More difficult to escape

The atmospheric evolution model (Lammer’s model) cannot explain the N / O

ratio of Venus and Mars simultaneously

It is not easy to explain the evolution of the abundances

The key: study the tendency of N+ / O+ ratio of escape

as a function of Solar forcing

NN++ ? ?

NITRO in-situ s/c measurements Mass spectrometer (cold): BernIon analyzers (0.001 - 40 keV): (1) Narrow mass range: Kiruna (2) Wide mass range: IRAP, ToulouseIon mass analyzer (> 30 keV): UNHElectrons: MSSLMagnetometer: GrazWaves (ΩN≠ΩO): Prague

Search Coil (ΩN≠ΩO): LPC2ELangmuir Probe: BrusselsENA monitoring substorms: BerkeleyASPOC (s/c potential control): s/c subsystem

NITRO remote sensing s/c Optical emissions: LATMOS & Japan (1) N+: 91 nm, 108 nm (2) N2

+: 391 nm, 428 nm

(3) NO+: 123-190 nm, 4.3 µm (4) O+: 83 nm, 732 / 733 nmMass Spectrometer: N, cold N+: GSFCIon analyzer (< 0.1 keV): KirunaElectrons: UK

Langmuir Probe: Brussels Ionospheric optical camera: TBD Magnetometer: Waves (ΩN ≠ ΩO): Prague

Search Coil (ΩN ≠ ΩO): LPC2E Orléans Ion analyzer (< 50 keV): Japan

North

South

In-situ s/c: Spinning

~800 km x 6 RE

i ~ 69°

Remote-sensing s/c: 3-axis stabilised

H ~500 x 2000 km

Ring Current

N+

N+

N+

N+

Upwelling: ~10 eV

Injected

~10 keV

N+

Upwelling:~10 eV

Small Mission proposal submitted to ESA: 2012

PI: M. Yamauchi, Co-PI: I. Dandouras

“Quad Chart” submitted to NASA (Heliophysics):

January 2013

LOI for an M4 mission proposal submitted to

ESA: September 2014

Need for a “Nitrogen” mission

Understanding Nitrogen distribution around Earth and its escape mechanisms.

The N / O ratio differs strongly between the “sister planets”.

Nitrogen is a key-element for biomolecules.

There are no N+ / O+ ratio observations in the ~0.05 - 30 keV domain