Version 3.2 - 25th November 2015

Version 3.2 of AstroGrav is an upgrade containing major improvements to simulation evolution and object importing, together with many other improvements and bug fixes. This information is intended for existing users who are already familiar with AstroGrav and want to quickly find out about the main changes. This is a free upgrade for customers who have already purchased a license, so that all you need to do is download Version 3.2 and use it in place of your old version. If you have any problems with this new version, please don't hesitate to contact us so that we can help you out.

Version 3.2 of AstroGrav has the following new and improved features.

• Simulation Evolution
• Importing Objects
• Sample Simulations
• Other Improvements

Simulation Evolution

Version 3.2 of AstroGrav includes the following improvements to the way that simulation evolution works.

• The accuracy of solar system evolution has been greatly improved when dealing with close encounters between objects. This includes the evolution of moons and satellites, which are effectively in a permanent state of close encounter with their parent planet.
• The Evolve / Evolve To... command has been improved with the addition of an Animate on-off switch. With animation switched on, the command works the same as before, with the simulation's windows being updated after each time step. With animation switched off, the simulation's windows are only updated when evolution is complete, making evolution very much faster in most cases. If non-animated evolution takes more than a couple of seconds, a progress bar is displayed to indicate how long it's going to take and to give you the opportunity to cancel evolution if desired.
• The Evolve / Settings... command has been enhanced with the addition of a Radiation Pressure on-off switch. This allows you to include the effect of radiation pressure when evolving a simulation. In most situations, the effect of radiation pressure is insignificant, but it can be an important factor in the evolution of small objects, and the smaller the object, the more significant the effect is. The best known example is the particles in a comet's tail that move in trajectories that are very different from their parent comet as a result of radiation pressure. Spacecraft, being much larger, are affected much less, but radiation pressure is still an important factor in planning their trajectories.

You can easily experiment with the effect of radiation pressure by opening one of the Solar System simulations and greatly increasing the Sun's luminosity. Increasing it by a factor of 10¹² produces a small change in the orbits of the planets, a factor of 10¹³ produces a major change in the orbits of the planets, and a factor of 10¹⁴ puts the planets into 'anti'-hyperbolic orbits where the repulsive force of radiation pressure is greater than the attractive force of gravity, causing the planets to accelerate away from the Sun forever. An 'anti'-hyperbolic orbit is indicated by a negative semi-major axis in tables and lists of orbital elements.

Importing Objects

Version 3.2 of AstroGrav includes the following improvement and bug fixes to the importing of objects into solar system simulations using the Edit / Import Objects... command.

• Importing without the Fast Import option is no longer animated, making it much faster than in earlier versions. If importing takes more than a couple of seconds, a progress bar is displayed to indicate how long it's going to take and to give you the opportunity to cancel the operation if desired.
• Importing without the Fast Import option now leaves the simulation at the same date and time as it started, instead of leaving it at the date and time of the last object imported.
• Importing without the Fast Import option is now even more accurate than in earlier versions as a consequence of the improved accuracy of evolution.
• Importing with the Fast Import option is unchanged.

Sample Simulations

Version 3.2 of AstroGrav includes the following updates to the solar system sample simulations.

• When opening one of the Solar System simulations, you now get a dialog displaying the question: Evolve to the present time? If you accept this dialog, the simulation quickly evolves to the current date and time without displaying the state of the system at any of the intermediate times. In many cases this takes less than a second, and if it takes more than a couple of seconds, a progress bar is displayed to indicate how long it's going to take and to give you the opportunity to cancel evolution if desired. If you reject the dialog, the simulation is left at the date and time at which it was last saved. This new feature has exactly the same effect as manually selecting the Evolve / Evolve To... command, leaving the default date and time unchanged, and selecting non-animated evolution.
• The Solar System simulations have had the physical elements of Pluto and its moons updated to take into account the recent discoveries made by the New Horizons mission.
• The Space Missions simulations have been made more accurate, and have been modified to take into account the effect of radiation pressure.
• The start date of the Solar System simulations has been changed from 01/01/2015 to 01/01/2016.

Other Improvements

Version 3.2 of AstroGrav also has many other minor improvements and bug fixes, including the following.

• A bug has been fixed that caused the Help / Report Fault... command to fail to work on some computers.
• The list of open windows at the end of the Window menu is now only displayed when there is more than one open window.
• The Dutch translations have been greatly improved.

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