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ESA Summer of Code in Space 2011 Jul 13 2011

The European Space Agency has announced the Summer of Code in Space 2011 (SOCIS), a great opportunity for students to get busy during the summer while contributing to a software project related to space. We are happy to announce that the ORSA open source software for celestial mechanics computations is applying to SOCIS 2011. Follow this link to read more and check possible project ideas.

Announcing SurfaceCoverage Tool May 12 2008

We've released a new tool: SurfaceCoverage. Please follow the link for more details.

New Tool Jul 1 2007

After over two years of quiet but active development, we're releasing today the first application based on the new ORSA code base: RendezvousWithVesta. This tool has been developed in support to the NASA DAWN mission, and allows to accurately simulate the dynamics of a spacecraft orbiting the asteroid (4) Vesta. It's main purpose is to determine what is the orbit of the DAWN spacecraft that provides the best coverage of Vesta's surface. This orbit will depend on Vesta's physical parameters, so it cannot be fully determined yet, as we don't know what is Vesta's mass with sufficient accuracy today. Nevertheless, by using RendezvousWithVesta the DAWN Science Team can investigate the possible effects of Vesta's mass on the overall surface coverage, and users in the general public are welcome to download the tool and experiment with it, and possibly collaborate with us on the ORSA-tools mailing list. Read more about it at the RendezvousWithVesta page and download it here.

RendezvousWithVesta is the first ORSA tool based on the Qt4 framework, that permits to easily develop open-source, GUI based applications and port them to Linux, Mac and Windows. Other improvements include the possibility to import/export SPICE kernel files, the accurate treatment of non-spherical effects from extended bodies (including 3D visualization), real time plotting capabilities, and arbitrary floating point precision. For the future, we expect to release many tools with specific capabilities such as this one, while working towards the realization of a general purpose graphical tool, such as the now outdated tool released with ORSA-0.7.0 over two years ago.

ORSA@work: Visualization of the spin state of asteroid (99942) Apophis Aug 16 2005

ORSA has been used to visualize the perturbation to the spin state of the asteroid (99942) Apophis, previously known as 2004 MN4, during a very close approach to Earth in 2029. Check out the ORSA@work page for more details.

ORSA@work: The Rosetta's Close Approach with Earth Feb 28 2005

ORSA can be used to visualize the Rosetta's close encounter with Earth. Check out the ORSA@work page for more details.

Development News Feb 8 2005

First of all, a new developer has joined the ORSA development team: Greg MacDonald. Greg is a C++ and computer graphics expert, and is also familiar with the Qt library. Greg is already working actively to improve the 3D visualization code. Welcome Greg!
Orbit Determination from Observations: a new tool is being developed to allow the determination of the orbit of an asteroid/comet using its astrometric observations. A development version will be available on the CVS soon, probably in less than one week from now.
Eclipses: graphical rendering of Eclipses will be possible in the forthcoming version of ORSA, see the image on the right. The relative code has not been committed to CVS yet.
In collaboration with Ben Joseph, a tool to import numerical integrations from the GTDS package to ORSA has been developed, called gtds2orsa, see this page for more details.
Trolltech has announced that "Qt for Windows will be available under both a commercial license and the open source GPL license starting with the next major production release of Qt, version 4.0, which is expected in the second quarter of 2005." Since ORSA is released under the GPL license, this means that it will be possible to develop and distribute winorsa without the necessity of a commercial Qt license. This will allow more people to develop under Windows, improving winorsa and ORSA itself. ORSA will need to be ported from Qt 3.x to Qt 4.x after the release of Qt 4.0.

ORSA 0.7.0 for Mac OS X released Jan 18 2005

The Mac OS X distribution package, contributed by Markus Bongard, is now available. Check out the download page for more details.

ORSA 0.7.0 released Jan 12 2005

We are releasing today ORSA 0.7.0. Source tarball, static Linux-i586 binary and Windows installer are already available. Changes include a rewrite of the Relativistic Corrections, Multipole Expansion (useful i.e. for low-Earth artificial satellites), texture support for all the Solar System planets (the textures can be downloaded automatically using the ORSA download tool), an URL with up-to-date GPS sats ephemeris, and the possibility to force the planets+Moon to the same position and velocity of the JPL ephemeris file. Check out the download page for more details.

ORSA@work: Distributed Computing and Near Earth Objects Hazard Monitoring Nov 14 2004

A Distributed Computing System for Near Earth Objects Hazard Monitoring is under development. Check out the ORSA@work page for more details.

ORSA@work: Close Encounters with Earth and Moon Oct 5 2004

We have compiled a list of close encounters between all the Near Earth Asteroids and the Earth-Moon system. Check out the ORSA@work page for more details.

ORSA 0.6.2 released Oct 1 2004

We are releasing today ORSA 0.6.2, as a source tarball and as a static Linux-i586 binary. Many bugs have been fixed, especially in the GUI. The numerical library has been improved, with some possible optimizations and speed-ups. Check out the download page for more details.

ORSA@work: The Glanerbrug meteorite by Marco Langbroek Sep 27 2004

Marco Langbroek has realized an animation [MPEG, 2.7 Mb] showing the Glanerbrug meteorite hitting the Earth. Check out the ORSA@work page for more details.

ORSA@work: 2004 ST26 close approach with the Moon Sep 24 2004

Another nice close approach, this time between the asteroid 2004 ST26 and the Moon, is available in this animation. Check out the ORSA@work page for more details.

New ORSA presentation and demo movie available Sep 3 2004

A new ORSA presentation [PDF, 622 kb] and a new ORSA demo movie [MPEG, 30.5 Mb, 13 min.] are available. Check out the documentation page for more details.

ORSA@work: 2004 FU162 close approach with Earth Aug 24 2004

Click on the right image to view the animation showing this spectacular close approach, and check out the ORSA@work page for more details.

ORSA 0.6.1 for Mac OS X released Jul 16 2004

The Mac OS X distribution package, contributed by Markus Bongard, is now available.

ORSA 0.6.1 released Jul 8 2004

This release fixes a OpenGL problem related to textures/lighting.

ORSA 0.6.0 released Jul 7 2004

We are releasing today ORSA 0.6.0, as a source tarball and as a static Linux-i586 binary. The Mac OS X and Windows versions are not ready yet, and we hope to release them soon. More details on this release will be published tomorrow.

What is ORSA

ORSA is an interactive tool for scientific grade Celestial Mechanics computations. Asteroids, comets, artificial satellites, Solar and extra-Solar planetary systems can be accurately reproduced, simulated, and analyzed.


  • accurate numerical algorithms
  • use of JPL ephemeris files for accurate planets positions
  • Qt-based graphical user interface
  • advanced 2D plotting tool and 3D OpenGL viewer
  • import asteroids and comets from all the known databases (MPC, JPL, Lowell, AstDyS, and NEODyS)
  • integrated download tool to update databases
  • stand alone numerical library liborsa
  • save and restore session from a single file


The main goals of the ORSA project are:

  • create a common infrastructure among the existing celestial mechanics programs and standards
  • use an object oriented programming language (C++), CVS and auto-configuration tools to achieve a good design, rapid development and maintainability
  • implementation of state of the art orbit integration algorithms, with concerns on accuracy, performance and interaction options
  • develop command-line and graphical applications with 3D capabilities (OpenGL)
  • support for High Throughput Computing systems (i.e. Condor) and GRID
  • keep the project under the GPL

The ORSA project is hosted by SourceForge.

Website last updated: May 12 2008
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