NASA Technical Reports Server (NTRS) 20110013274: Vesper - Venus Chemistry and Dynamics Orbiter - A NASA Discovery Mission Proposal: Submillimeter Investigation of Atmospheric Chemistry and Dynamics

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Vesper - Venus Chemistry and Dynamics Orbiter -A NASA Discovery Mission Proposal:
Submillimeter Investigation of Atmospheric Chemistry and Dynamics
G. Chin
NASA Goddard Space Flight Center, Greenbelt, MD USA, [email protected]
of wind. A science mission duration of two Venus
years offers the opportunity to characterize
variability of atmospheric phenomena.
The main science instrument on Vesper is the
Submillimeter Line Spectrometer (SLS). The SLS
combines a 50 cm aperture, spaccraft fixed telescope
with a dual-band, tunable, high spectral resolution,
\\:h)" \' C'IUC."I'-
spectroscopic receiver using proven space-qualified
Vesper conducts a focused investigation of the
technologies.
chemistry and dynamics of the middle atmosphere
SLS derives its heritage from a number of flight
of our sister planet- from the base of the global
instruments. Space flight Schottky diode- based
cloud cover to the lower thermosphere. The middle
submillimeter radiometers include the UARS MLS
atmosphere controls the stability of the Venus
EOS Aura MLS, SW AS, MIRO/Rosetta, and Odin:
climate system. Vesper determines what processes
SLS also derives its heritage from the HIFI
maintain the atmospheric chemical stability, cause
instrument on the Herschel Space Observatory
observed variability of chemical composition,
launched successfully in 2009. A 4096-channel
control the escape of water, and drive the extreme
Chirp Transform Spectrometer (CTS) is currently
super-rotation.
flying on MIROlRosetta.
The Vesper science investigation provides a
SLS consists of a 50 cm (projected) offset
unique perspective on the Earth environment due to
parabolic reflector telescope followed by two
the similarities in the middle atmosphere processes
submillimeter heterodyne receivers. Center-band
of both Venus and the Earth. Under- standing key
operating frequencies are 470 GHz (Band I) and 560
distinctions and similarities between Venus and
GHz (Band 2). Each receiver includes a very high
Earth will increase our knowledge of how terrestrial
resolution l/dl > IxIO') CTS having a 400 MHz
planets evolve along different paths from nearly
instantaneous bandwidth and 4096 channels.
identical initial conditions.
Individual channel bandwidths are - 100 kHz. Both
Instrumen- SClEHlCe -n~-----' mil" receivers can be tuned over ±30 GHz, pennitting
tallon Dnve-rs
spectral line observations anywhere within 440-500
SJbmlli· • O·~tt ~'ln~s
ml!~~' j .. '! • -:Tn!·.!Ilu~::I GHz (0.60-0.68 mm) in Band I and 530-590 GHz
S::;e::!r::T' • t-JL ,d3n::e (0.51-0.57 mm) in Band 2. The two bands include
.1,'lSLSl ~=rs ~ \'~)' all trace gases known to be present in the Venus
• E<.e 1Si"'E \,\:",
ijca :;Ct"ErE~E upper atmosphere as well as several undetected
c: ",caiE le ~~~ species.
f.!<:·JIJt·Jr
The figure below shows a depiction of the SLS
NE,U 1J11Tc.· • a:;:u~ ~",e
',i(l~l.arj "A"d:; instrument with its 50-cm off-axis Cassegrain
lrrc.'ec • a:;:u~ ~ ... e telescope and receiver and electronics components.
H:C
Ta~~r
(NUVlI
Ri:.jj(l • H~h IE'''EI res:;,
O:::;JllaUtol 1.r.·Jr p'oli E
&:;e'Te"t c·m:;~)· '.\lith
c~r ~'Ed
LEm:;e·.aturE,'
P"(>SSL .~
In a polar circular orbit, the Vesper science US:r:i..,lnt"'(1
instruments- Submillimeter Line Spectrometer 'L~-"'Q
(SLS) and Near Ultraviolet and Infrared Imager
(N1NI), and the Radio Occultation Experiment
(ROE)- provide a global, vertical, and local time
distribution of major and minor chemical
constituents, temperature, and direct measurements