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upgraded NITRO for M5 Nitrogen and Oxygen
Budget ExpLoration (NOBEL)
M. Yamauchi (IRF, Kiruna, Sweden) I. Dandouras
and H. Rème (IRAP, Toulouse, France) O. Marghitu
(ISS, Bucharest-Magurele, Romania) and NOBEL (ex.
NITRO) proposal team
M4 proposal ?
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Mission objectives
1. Earth diagnosis (exosphere/ escape) Study the
amount of both thermal and non-thermal escape of
major atmospheric components (nitrogen and
oxygen) from the Earth. This requires first
time exploration of the exosphere as well as
first time examination of isotope ratios in the
magnetosphere.
2. Atmospheric evolution The measurement quality
must enable modelling of the escape on a
geological time scale, and should be a good
reference in understanding planetary evolution
from their isotope ratio and N/O ratio.
What is to be measured
Magnetospheric density distribution and fluxes
for N, N2, O, and H. Energy distribution
of each species in the magnetosphere. Neutral
and ion densities for N, N2, O, O2, at
exosphere/ionosphere (gt 1000 km). Isotope ratio
of neutrals and cold ions of oxygen (16O, 17O,
18O) in both upper exosphere/ionosphere and
magnetosphere for a wide range of solar wind and
solar EUV conditions
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Why exosphere?
Poor observational knowledge (No knowledge of gt
800 km for nitrogen, gt 1500 km for oxygen, and
all altitude for isotope ratio) Varies
dynamically (Mars observation indicates unknown
factors other than EUV) Mandatory for escape
modeling (For thermal and some non-thermal
escape) Source of cold ions above the
ionosphere (They contribute feeding ions of
non-thermal escape)
He lt 800 km
O lt 700 km
N2 lt 500 km
O2
one order of magnitude variation with 40 change
in solar EUV-visible flux
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Why nitrogen and isotope ratio?
N2?N2?N whereas O2?O ?O (completely
different solar/geomagnetic dependence) Scientifi
cally important element (essential for
amino-acid, and a representative
volatile) Escaped amount could be significant
for biosphere (Escape matters if 1026
ions/s) Not well known, but now possible to
measure (impossible 5 years ago)
Used as indicator of escape from planet (For
better estimate, we need to know the difference
in the isotope ratio between different escape
processes) Poor observational knowledge (No
knowledge in the magnetosphere/ionosphere)
Mars atmosphere
Earth
Mars interior
Jupitor
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Where is the optimum orbit?
1. Non-thermal escape can be estimated by
covering both the exosphere and the inner
magnetosphere.
Orbital period 10 hr
resolution 0.1/slit x 20 slits
2. The same orbit enables measurements of
exosphere for both in-situ and remote sensing.
With 20 sec spin, altitude resolution 100 km
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Payload
Optional IR emissions (TBD) N, N2, N2,
O, O, Waves analyser (Prague) Search coil
(TBD) Auroral / airglow camera (Tohoku) ENA
monitoring (TBD) Cold ion/neutral mass analyzer
for fast sampling (Goddard) Potential Control
(SC subsystem)
Baseline Cold ion/neutral mass spectrometer
N/O and 17O/16O separation (Bern) Ion mass
analyzers (0.03 30 keV) (1) m/q lt 20
(Toulouse) (2) m/q gt 10 (Kiruna) Energetic
Ion mass analyzer (UNH) Magnetometer (Graz)
Langmuir probe (Brussels?) Electron analyzer
(London) UV/visible emissions (Tokyo?)
N, N2, N2, O, O,
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Accommodation
skip?
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Advantage of the Earth
Sufficient dry mass (many heavier
instruments) Sufficient telemetry (without large
antenna that blocks FOV) Low altitude conjugate
observations is possible (any low-altitude
spacecraft such as NASA mission, and Ground-based
observations such as EISCAT_3D conjugate gt 20
passes/yr)
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Advantage of the Earth
skip?
Covering area of EISCAT_3D
High sensitivity in more than 300 km diameter
(white area) 10 longitudinal range. ? 3 of
polar orbits traverses this region in
average. ? With T10 hours, NOBEL crosses once
every 15 days in average.
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Advantage of the Earth
skip?
Independent extra spacecraft possible
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Design
skip?
Spacecraft In-situ
orbital period 10 hr
attitude control Spin (22-26 sec)
attitude reference Sun-pointing
control method cold gas
time resolution 2 min
angular resolution //, ?, and anti-//
telemetry 100 kbps
life time 3 year
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Extra science
Planetary Evolution meaning of isotope ratio and
N/O ratio of a planet in terms of the escape
history. Exoplanet modeling tuning
interpretation of optical data on exoplanets by
having both spectral and in-situ
measurements. Ionosphere Physics ionization
chemistry and transport at the topside ionosphere
at different external conditions. Inner
Magnetospheric Dynamics using nitrogen as an
independent tracer from oxygen. Space Plasma
Physics (acceleration) different initial
velocities between M/q14 and M/q16 give extra
information.
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Summary

• With recently developed reliable instrumentation,
  NOBEL will systematically study
• the exospheric conditions,
• nitrogen budget,
• isotope ratio of cold ions/neutrals above 1000
  km
• The knowledge is mandatory in understanding in
  estimating present-days thermal/non-thermal
  escape as well as behaviors of exosphere.
• The required instrumentation can also answer
  questions in the other areas.

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END
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If the nitrogen escape is large,
1

• We can compare the two competing models more
  quantitatively
• N2 delivery model (from comets, asteroids)
• Volatiles are difficult to be included in
  proto-Earth (Temperature)
• Volatiles should have escaped during the time
  of outgassing (EUV)
• But amount of delivery is uncertain
• Expect neutral form with N2 in primordial Earth
• Protection of nitrogen from outgassing NH3
• Naturally expected if the proto-Earth included
  nitrogen (as NH3)
• NH3 rather than N2 is expected because of
  higher Tcondensation
• But difficult to protect from hydrodynamic
  massive escape
• Expect alkali form with NH3 in primordial Earth

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Nitrogen is missing on Mars
Jeans escape does not explain it.
Planetary formation does not explain
it. Condensation temperature of TC(N2) TC(CO)
ltlt TC(CO2) TC(NH3)
indicates that condensation of N and C most
likely occurred in the form of N2CO pair (
30K) or NH3CO2 pair (50 90K). Therefore, N2
content should be Mars gt Earth gt Venus.
N2-Delivery model does not explain it. It should
deliver on Mars too
???
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If the nitrogen escape is large
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Interpretation of isotope ratio 15N/14N will be
questioned because total nitrogen escape is
comparable between the Earth and Mars
? (a) Substantial Martian atmosphere could have
been delivered by comet? (b) Simple difference
in the escape mechanism? or (c) No outgassing
happened, or all outgassed air has been lost at
Early stage?
???
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Atmosphere formation models
Omit
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earth history
Omit