Abstract

The infrared thermal mapper (IRTM) was designed to measure the emitted and reflected radiance of Mars. Carried by the Viking Orbiter, the IRTM contains four small Cassegrainian telescopes which each image the same, seven circular areas. There is a total of twenty-eight channels in four surface and one atmospheric thermal bands from 6 μm to 30 μm and a broad solar reflectance band. All channels are sampled simultaneously, using the spacecraft scanning capability to map the radiance over small and large areas of the planet. All channels use thermopile detectors; spectral passbands are determined by a combination of interference filters, detector lense materials, antireflection coatings, and restrahlen optics.

© 1978 Optical Society of America

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References

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  1. H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
    [CrossRef]
  2. S. C. Chase, Appl. Opt. 8, 639 (1969).
    [CrossRef]
  3. T. C. Clarke, Jet Propul. Lab. Tech. Mem 33–719 (1975).
  4. H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
    [CrossRef]

1977 (1)

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

1972 (1)

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

1969 (1)

Chase, S. C.

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

S. C. Chase, Appl. Opt. 8, 639 (1969).
[CrossRef]

Clarke, T. C.

T. C. Clarke, Jet Propul. Lab. Tech. Mem 33–719 (1975).

Jakosky, B. M.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Kieffer, H. H.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

Martin, T. Z.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Miner, E.

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

Miner, E. D.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Münch, G.

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

Neugebauer, G.

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

Palluconi, F. D.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Peterfreund, A. R.

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Appl. Opt. (1)

Icarus (1)

H. H. Kieffer, G. Neugebauer, G. Münch, S. C. Chase, E. Miner, Icarus 16, 47 (1972).
[CrossRef]

J. Geophys. Res. (1)

H. H. Kieffer, T. Z. Martin, A. R. Peterfreund, B. M. Jakosky, E. D. Miner, F. D. Palluconi, J. Geophys. Res., 82, 4249 (1977).
[CrossRef]

Other (1)

T. C. Clarke, Jet Propul. Lab. Tech. Mem 33–719 (1975).

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Figures (8)

Fig. 1
Fig. 1

Exploded view of the Viking IRTM. In flight, the instrument is covered by a solar blanket.

Fig. 2
Fig. 2

Functional block diagram.

Fig. 3
Fig. 3

Telescope schematic drawing. Except for filters the four detector packages are identical. The D telescope is of smaller diameter.

Fig. 4
Fig. 4

Fields of view of the IRTM, MAWD, and imaging systems: (a) Ideal registration of the IRTM, MAWD, and the VIS cameras. The actual array is about 5% smaller due to a telescope focal length design change. (b) Alignment of VO-1 IRTM and VIS determined by in-flight observations of Mars. The dashed extension of spot 1 shows the motion during the IRTM integration time for a ¼°-sec−1 scan platform slew. The triangle is the C axis (boresight) of the IRTM; the small circle is the scan platform reference direction. (c) Same as (b), but for VO-2. The dimensions of the IRTM array are identical to VO-1, they are given here in degrees for convenience.

Fig. 5
Fig. 5

IRTM relative spectral response; data are for VO-1; VO-2 differs neglibibly.

Fig. 6
Fig. 6

IRTM normalized spatial response; (a) and (b) are computed for Fraunhofer diffraction for the A telescope at 20 μm: (a) Response to an on-axis uniform source as a function of source radius (left-hand scale). (b) Response to a uniform half space as a function of off-axis distance (right-hand scale). (c) Observed A telescope response to circular sources in laboratory EFS test. Small circles are collimator data, square are for distant blackbody. The change beyond 95 mrad was less than system uncertainty (left-hand scale). (d) Observed A telescope response crossing a hot limb of Mars normalized to the on-planet radiance. This corresponds to the theoretical curve (b). The dashed curve shows the result of correcting for atmospheric opacity by assuming that the edge of the radiance source is 19 km (2.9 mrad) above the planetary surface (right-hand scale).

Fig. 7
Fig. 7

IRTM thermopile array. The sapphire substrate disk is 1.25 cm in diameter. There are six Sb–Bi junctions under each of the 0.030-cm diam black sensitive areas.

Fig. 8
Fig. 8

IRTM radiometric response. Calculations are for VO-1 spectral response and ignore the small nonlinearity measured during calibration.

Tables (2)

Tables Icon

Table I IRTM Design Summary

Tables Icon

Table II Optical Materials

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