I33 NIMS Objectives

Here are the science objectives for Galileo's Near-Infrared Mapping Spectrometer (NIMS) during I33:

  1. The major scientific objective for NIMS is to map the thermal emission from Io's Jupiter-facing hemisphere. Galileo has only seen this hemisphere at poor spatial resolution, and there may be significant differences in the distribution and power output of the hot spots. The longitudinal distribution of hot spots has implications for the mechanism of tidal dissipation within Io and I33 provides us a unique opportunity to test if the distribution of hot spots is similar or significantly different from that of the hemisphere of Io that faces away from Jupiter.
  2. Thermal maps of several hot spots never before seen by NIMS at high spatial resolution (such as Masubi and Kanehekili)
  3. A thermal map of Pele in darkness. NIMS data from I27 showed temperatures consistent with ultramafic volcanism at Pele, but much of the data suffered from saturation and the distribution of temperatures within Pele could not be mapped. We will use the lowest NIMS gain state during this observation, which should result in a lower saturation level and therefore improved determinatio of the temperatures.
  4. The NIMS maps of SO2 distribution, and the variation in the yet-unidentified 1-micron absorber, are other objectives of
    significant value.

Here is a list of NIMS observations currently planned:

INTHPELE01

Observation of hot spot Pele in darkness to measure thermal emission.

INKANEHE01

High resolution observation of Kanehekili hot spot in reflected sunlight to measure thermal emission and to investigate surface
composition. Kanehekili is a bright hot spot often observed from Earth, and one of the most persistently active on Io. It has
never been observed at high spatial resolution by NIMS.

INMOSAIC01

Observation of hot spot Masubi (never before observed by NIMS at high resolution) to measure thermal emission and distribution of SO2.

INMOSAIC02

Observation of Amirani/ Maui region to detect thermal emission and to investigate surface composition. Amirani was observed by NIMS in I24 and I27, and there were significant changes in thermal output between these observations. This observation in I33 aims to detect further changes, which will help our understanding of the emplacement of the Amirani flow, the largest known lava flow in the Solar System.

INREGION01

Observation of large region in Jupiter facing hemisphere to map thermal emission from hot spots and to investigate distribution
of thermal output, as well as that of SO2 and other compounds.

INGLOBAL

Global observation to map thermal emission from hot spots and to investigate distribution of SO2 and other compounds. This
observation will cover more area than REGION, but will return fewer samples to fit in with data playback constraints.

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