View source for SIR-2

[[File:SIR-2 Logo.jpg|thumb|SIR-2 Mission Logo]]

The '''SIR-2''' instrument is a redesigned, highly compact, monolithic grating, near infrared spectrometer chosen to be a payload on the Indian [[Chandrayaan-1]] satellite. It is an [[ESA]] project, and is built by [[Max Planck Institute for Solar System Research]], [[Polish Academy of Sciences]] and [[University of Bergen]].

[[File:SIR-2 Instrument.jpg|thumb|SIR-2 Instrument parts]]

== Mission ==
The mission of the instrument is to map the lunar surface in the near infrared spectrum from 0.9 - 2.4 μm with an
unprecedented resolution of 6&nbsp;nm. The purpose of this is to obtain information on the mineral
composition of the moon, which in turn will help getting insight into a number of questions:

* What is the cause of the global asymmetry of the moon, which on the far side has a thicker crust and lacks the Mare structures which are characteristic for the near side?
* What was the early thermal evolution of the moon?
* What is the vertical and lateral structure of the lunar crust and how did it develop?
* What is the composition and structure of the lunar mantle?
* Why is the moon different from other planets and how do planets work in terms of surface processes, heat transfer, and geologic evolution?
* Are the Apollo geophysical measurements representative of the moon, or are they only valid for the small regions around the Apollo landing sites?

=== Similar missions ===
The instrument is a redesigned version of SIR, which was flown on board the [[SMART-1]] technology satellite. SIR performed the same mission, but had a problem with dark current induced noise due to varying temperatures caused by differences in heat flux from the light and dark side of the Moon. SIR-2 will attempt to improve this, mainly by using a detector with an embedded thermoelectric cooler and a digital controller to keep the detector temperature stable. This will stabilize the dark current noise, making it simple to subtract it since it will have an almost constant level.

== Electronics ==
The control unit of SIR-2 is based on a [[System-on-a-chip]] design, minimizing the size and power consumption of the unit. A central component is the radiation hardened RTAX2000S Axcelerator [[FPGA]], containing a [[LEON]] (LEON3FT) [[SPARC]] compliant [[CPU]], communications interface [[Intellectual property]] cores, and custom interfaces to the rest of the instrument.

== References ==
*[http://adsabs.harvard.edu/abs/2009epsc.conf..683M SIR-2 on Chandrayaan-1 - First results]
*[http://adsabs.harvard.edu/abs/2011Icar..213...43B An in-depth look at the lunar crater Copernicus: Exposed mineralogy by high-resolution near-infrared spectroscopy]
*[http://adsabs.harvard.edu/abs/2011LPI....42.2390B Study of Spectral Characteristics of the Central Peak Region of Tycho Crater Using the SIR-2 Data On-Board Chandrayaan-1]
*[http://adsabs.harvard.edu/abs/2009epsc.conf..225B SIR-2 as an important geological investigative tool]
*[http://adsabs.harvard.edu/abs/2010EGUGA..12.7031M Data from the SIR-2 Experiment on Chandrayaan-1]
*[http://adsabs.harvard.edu/abs/2011LPI....42.1067B A Near-Infrared Reflectance Survey Across Lunar Crater Aristoteles]
*[http://adsabs.harvard.edu/abs/2011LPI....42.2390B Study of Spectral Characteristics of the Central Peak Region of Tycho Crater Using the SIR-2 Data On-Board Chandrayaan-1]

== External links ==
* [https://web.archive.org/web/20110512162058/http://www.mps.mpg.de/projects/sir/ Official website]

[[Category:Indian lunar exploration programme]]
[[Category:Spacecraft instruments]]