Lunar Laser Ranger

Translations: French

The main goal with LLR is to achieve precision to a few picoseconds, which corresponds to about one millimeter in range to the moon. Using this information, we will be able to gauge the relative acceleration of the earth and Moon toward the sun (like a modern-day Leaning Tower of Pisa experiment) in order to ascertain the free-fall properties of earth's gravitational self-energy, to name a few.


There is currently no Lunar Laser Ranging system in the southern hemisphere, and the international LLR network is very small as well. We now have an opportunity to install an LLR system here in South Africa - This will be the first major project at Matjiesfontein.

Our goal with the Lunar Laser Ranger in not to 'upsize' current technologies, but redevelop the system. This will help us achieving our specific goals as well as sidestepping some of the problems experienced by other LLR facilities.

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There are many different subsystems which must be developed:

  • High power picosecond laser (In collaboration with the National Laser Centre, CSIR)
  • Telescope (We are receiving a 1m telescope from Observatoire de la Cote d'Azur, which needs to be refurbished)
  • Timing Subsystem
  • Control Subsystem
  • Software for control and data processing


High Power Picosecond Laser

The development of this laser is in collaboration with the National Laser Centre, which is part of the Council for Scientific and Industrial Research (CSIR).

One M.Sc. has been completed and one PhD is in progress on this research. The photo below shows one of the lasers that were built towards the final laser system, being demonstrated to DST (Department of Science and technology) personnel.



A 1m Cassegrain telescope was donated by Observatoire de la Cote d'Azur for the development of the LLR. The telescope is expected to be shipped middle of April and arrive in South Africa beginning of May 2008. Refurbishments will start as soon as the refurbishment site and buildings are ready and the relevant students enrolled. We expect at least 1 PhD and 2 M.Sc. / M.Tech degrees to come from this part of the project.

The telescope mount (left) and tube (right) in its' storage container in France. Dr. Francis Pierron from OCA is with the telescope.



Software to run data processing of a SLR system is currently under development in-house. It is developed in such a way that it can be used on the new LLR system as well.


 Current Developments

Tamsen Emmerich is doing a project on the LLR system. Updates on her work are on the LLR - Tamsen page.