Aug 2010

After all this time ...

Satellites has been in work since November 2008. One of the first pieces of the application to be finished was the part which performs orbital predictions and, as part of that, functions which convert between 'sky coordinates' and 'geographic coordinates.' Imagine my surprise when I found a mistake in the software which calculates a satellite's latitude and longitude.

The error is related to the adjustments made for the fact that the Earth is not perfectly spherical; it has a very slight effect, probably invisible, but it is a reminder that no software of any complexity is entirely free of errors. The upcoming v1.5 has this mistake corrected.

v1.5 and "Settings"

I have made some kind of mistake in Satellites v1.4 which causes the "Settings" tab to not be shown on the bottom tab bar. I have not yet found the cause of this (and I have been looking and testing for several days), so my solution will be to push a new release out soon which contains a new "Settings" mechanism.

I've been planning to change the way settings operates to allow the observer's location to be set more easily. This feature change will be released soon -- the code completely replaces the "Settings" code in v1.4 and so should fix the above problem.

My apologies for the inconvenience.

v1.5 in design

Satellites is now pretty much what I wanted for a first release. I have two major updates that I'm considering for future releases: one is to add a "sky view" to show the ISS path through the stars; the other is to make the "earth view" more flexible. I've done some preliminary coding for the latter that I'll show an example of here.

This view may look just like what
Satellites does now but there is a subtle difference. It's most visible in the latitude lines at 30° and 60° -- you'll notice they are slightly curved, and the North and South Poles are not visible. Previous versions of Satellites have viewed the Earth as it would be seen from infinity (an orthographic view), but this view is from about 60,000 miles above the equator (a perspective view).

Hopefully, I can allow the user to observe the Earth and the ISS from locations that are closer to and not centered on the Earth, for example from 1000 miles behind the ISS as it orbits showing the Earth revolving underneath.

Further into the future, I'd like to provide coverage for more satellites than just the ISS and the occasional Shuttle flight (only two, maybe three, missions left to fly). In private testing,
Satellites is quite capable of handling hundred of orbiting objects.

Lots of ideas ...