HRS Camera

The HRS instrument mounted on the satellite, next to the VEGETATION instrument

Operating principle and optical path

The HRS instrument is designed to acquire images in the panchromatic band at viewing angles of 20° forward and aft of the satellite. It can thus obtain stereopair images quickly to generate digital elevation models.

HRS uses the same pushbroom scanning technique as HRG
HRS uses the same pushbroom scanning technique as HRG

HRS instrument architecture

The HRS instrument consists of:

  • A carbon-skin sandwich/aluminium honeycomb instrument panel supporting the mechanical interface with the SPOT 5 satellite and the instrument systems.
  • A stereo video module (MVS), which handles and processes data from the detection units, actively controls the instrument’s temperature and provides the ancillary systems required to operate it (chiefly power and TM/TC).
  • A thermal cocoon encloses the temperature-sensitive components vital to achieve the instrument’s required performance, i.e.:
    · The front and rear objectives, mounted on a quasi-isostatic structure to ensure stability. The objectives collect incoming light in the panchromatic band and focus it onto the lines of detectors. It filters out all rays outside the panchromatic band to minimize stray light.
    · The front and rear detection units, which house the CCD sensors and electronics. These units convert the light signal into anelectrical signal

The HRS instrument during integration in October 2000
The HRS instrument during integration in October 2000
The cocoon maintains the instrument's components within the required temperature range.

HRS instrument during tests
HRS instrument during tests


Technical data

HRS technical data


90 kg


128 W


1×1,3×0,4 m

Field of view

+/- 4°

Focal lenght

0.580 m

Detectors per line


Detector pitch

6.5 µm

Integration time per line

0.752 ms

Forward/aft viewing angle



Spectral range (panchromatic band)

0.48 µm – 0.70 µm

Ground sample distance

  • Across track
  • Along track

10 m
5 m

Modulation transfer function

> 0.25

Signal-to-noise ratio

> 120


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