Temperature Measurements in the Lower Thermosphere Utilizing the RAIDS Near Infrared Spectrometer Physical Sciences Laboratories May 19, 2010 A. B. Christensen 1, J. H. Hecht 1, R. L. Bishop 1,S. A. Budzien 2, A. W. Stephan 2, P. R. Straus 1, Z. Van Epps 2 1 The Aerospace Corporation, Space Science and Applications Laboratory 2 Naval Research Laboratory, Space Science Division Work supported by The Aerospace Corporation's Independent Research and Development Program.

2 ABSTRACT Specification of the temperature in the lower thermosphere (90 – 200 km) is a major objective of the RAIDS experiment on ISS. Near Infrared Spectrometer(750 – 900 nm) and 3 photometers: OI(6300), OI(7774), and O2Atm(0-0) 765nm observe dayside and nightside limb airglow. Temperature derived from O2Atm(0-0 and 1-1) spectral band shape is consistent with models and SABER observations. Brightness of the dayside 0-0 and 1-1 bands consistent with MSIS and AURIC models.

O 2 Energy Level Diagram Atmospheric System Circled 3

4 RAIDS Remote Atmospheric and Ionospheric Detection System RAIDS comprises 7 instruments On a mechanically scanned platform with 1 staring FUV instrument. The near infra-red photomultiplier tubes reside in a separate radiatively cooled detector box. cooled housing to approximately -20 C. 1 – Phot 2 – Phot 3 - NIR Spectrometer (700– 900) 4 - NUV Spectrometer ( FUV Spectrograph (130 – 170) 6 - MUV Spectrometer (190 – 320) Phot 8 - EUV Spectrograph (55 – 111)` Courtesy of NASA

Geometry RAIDS Limb Viewing Geometry 5 7/18/ km 750 km 16.5º Scan 6 km Resolution Field of View 0.1º x 2.1º 3000 km Courtesy of NASA

1/8m Ebert-Fastie Spectrometer 6 NIR instrument incorporates a fiber optic feed to a cooled (-20 C) photomultiplier tube

NIRS SPECTRA Top Panel: LOS T0-0 = 462 ±21K LOS T1-1 = 621 ±69 K Altitude = 128 km Bottom Panel: T0-0 = 288 ± 3 K T1-1 = 306 ± 15 K Altitude = 116 km The shape of the O2 atm bands change with temperature 7

Spectral Synthesis of NIRS data Temperatures of the O2 Atm (0-0, 1-1) bands and the radiance of other features in the spectrum were obtained using a multiple regression approach. Features in the Synthetic Spectrum model –O2 Atm 0-0 –O2 Atm 1-1 –N2 1 st Positive –N2 + Meinel –OI –OI –OII

Processed Temp Data March 24,

RAIDS O2Atm (0-0) Temperatures vs. Model MSIS for F10.7 = 70, Tinf = 777 K 10

Comparison of NIRS and SABER Ktemp March 24,

12 NIRS Temp00 – MSIS Model March 24, 2010

13 Comparison NIRS and SABER March 24 Dayside NIRS corrected NIRS temp00 – MSIS model SABER Ktemp scan to scan differences

O 2 ( 1 Σ) Photo Chemistry in the Thermosphere 14 PRODUCTION: O( 1 D) + O 2  O 2 ( 1 Σ) + O( 3 P) Energy Transfer O 2 + hν  O 2 ( 1 Σ) Solar Res. Scatt. LOSS: O 2 ( 1 Σ) + N 2, O, O 2  O 2 + N 2, O, O 2 Quenching O 2 ( 1 Σ)  O 2 + hν Spon. Rad.

Modeled O 2 ( 1 Σ) v’=0 and v’=1 Density and Emission Profiles 15

Model and Dayside 0-0 and 1-1 Limb Brightness 16

CONCLUSIONS Instruments on the RAIDS experiment are alive and well. Dayside photometer observations are complicated by foreground scattered light from the ISS. Temperature of the O2 atm (0-0 and 1-1) bands have been derivedfrom the near infra-red (NIRS) data. Temperatures are in general agreement with models and measurements at the lower altitude range of the NIRS data The altitude profiles of the O2 (0-0 and 1-1) bands are in good agreement with the model. Hence, an additional high altitude source may not be required as previously postulated. Large scan to scan differences are suggestive of TIMED/SABER kinetic temperature measurements in lower thermosphere 17

Nightside Photometer Data 18 Red = OI 6300 (counts in 0.1 s * ) Black = OI7774 (counts in 0.1s) Green = RAIDS scan angle (increasing angle is looking at lower altitudes)

Nightside OI7774 and OI 6300 versus Platform Scan angle Estimated radiance of OI7774 ~ 200R slant view VanRhijn factor ~ 20 Nadir brightness ~ 10 R If this is an ionospheric signature of radiative recombination, the peak F –region electron Density ~ 1 e6 /cm3 19

20 RAIDS Installation on ISS RAIDS being attached to the porch of the Japanese module 7/18/ RAIDS Courtesy of NASA

March 24, 2010 O2( 1 Σ) 0-0 Temp. and 0-0 and 1-1 Brightness in Rayleighs 21