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Overview

 

         

ROSAT is a three-axis stabilized satellite with a total mass of 2.429 tonnes. The telescope assembly is 4 m in length. The scientific payload consists of:

The X-ray telescope (XRT)

with its 2.40m focal-length mirror assembly consisting of four nested Wolter-I mirrors. The focal plane instrumentation consists of a carousel on which there are two position-sensitive proportional counters (PSPCs), each with a filter wheel carrying a boron filter, and a high-resolution imager (HRI) (for details see Chap. 2, 3, 4, and 5).

The wide-field camera (WFC)

with its 0.525m focal-length mirror assembly consisting of three nested Wolter-Schwarzschild mirrors (co-aligned with the XRT). The focal plane instrumentation consists of a curved microchannel plate (MCP) a carousel containing 8 filters, of which 6 are science filters (for details see Chap. 6).

The rest of the payload includes:

The on-board computer (OBC) and the command and data handling system (CDHS)

The attitude measuring and control system (AMCS)

including:

1. two star trackers (STC-1 and STC-2) used for optical position sensing and attitude determination (Sect. 1.2.5). An additional star tracker (WFC STC) provides the WFC with independent attitude determination, however this sensor is not (at present) used for spacecraft control.
2. four gyros and three reaction wheels used for attitude control (Sect. 1.2.3)
3. a sun sensor (Sect. 1.2.7)
4. a magnetometer (Sect. 1.2.8)

Two South Atlantic Anomaly detectors (SAAD-1 and SAAD-2)

used to safe-guard the health of the focal plane instruments during passage through the South Atlantic Anomaly (SAA) and particle belts (Sect. 1.2.6)

Power is supplied through three solar panels  providing 1kW of power during sunlit parts of the orbit, and through a rechargeable battery during the shadow phase (S/C night, up to 40 minutes per orbit). 

  
Figure 1.1: Schematic view of the ROSAT spacecraft. [ROSAT AO-21991].

A schematic view of the ROSAT spacecraft is shown in Figure 1.1.