Chandrayaan-1 is the Indian Space Research Organisation’s (ISRO) mission to the moon, with the main scientific objectives of photo-selenological and chemical mapping of the lunar surface. It was successfully launched from Satish Dhawan Space Centre, Sriharikota on October 22nd 2008 at 06:22 local time.  

X-ray Solar Monitor (XSM) is a part of the payload selected for Chandrayaan-1. It is an improved version of the instrument already flown on ESA’s SMART-1 mission. XSM measured the X-ray spectrum of the sun and acted as a calibration system for the C1XS instrument provided by the Rutherford Appleton Laboratory (RAL, UK). The combined C1XS-XSM data gave an absolute abundance measurement of the elements on the surface of the moon. In addition to being a part of the C1XS measuring system, XSM provided significant independent information about the solar corona.

The XSM instrument consists of two main parts, the sensor unit and the main electronics board. The sensor unit contains a Peltier cooled high purity silicon PIN radiation detector, the detector’s front-end electronics and an electro-magnetically controlled shutter for shielding the detector from radiation when it is not in use. The shutter also has a calibration source mounted on it, to allow in-flight calibration of the detector. The XSM main electronics board, situated in the C1XS housing, contains all the necessary processing and controlling functions of the instrument.

The design, fabrication and testing of XSM was done by Oxford Instruments Analytical Oy, in close collaboration with the Division of Geophysics and Astronomy at the University of Helsinki. The calibration was performed at the Laboratory of electronic structure of the University of Helsinki.

Unfortunately the radio contact with the Chandrayaan-1 spacecraft was lost on August 29th 2009


See more about Chandrayaan-1 project:

Indian Space Research Organisation - ISRO

Chandrayaan-1 ISRO India


University of Heksinki C1 XSM

University of Helsinki - Space Research