It’s been many years since I committed my crime and it will be many more before my life-long sentence ends. There’s a saying that confession is good for the soul. Perhaps it would be best if the truth got out now. The recent explorations by Spirit and Opportunity indicate that the truth is about to be revealed anyhow, so there’s certainly nothing to lose…
We were stationed on a scientific outpost on the planet you now call Mars and one night, after ten of your centuries, the stress got to us and we threw a pretty wild party.
One of the other engineers (you wouldn’t be able to pronounce her name) got rather reckless with the mass driver and to make a long story short, that’s how the fifth planet got destroyed.
Over the next several of your decades, we all periodically took turns shooting the mass driver at some of the debris. At some point, it started getting more and more competitive to see who could come up with the fanciest shot (the “three dimensional billiards shot” which ended with two debris fragments orbiting Mars as moons with retrograde orbits was particularly spectacular).
On my last turn, I planned to fire a shot that would “slingshot” around your planet before traveling back out to the debris field where the fifth planet used to be. That’s when “The Accident” happened. The mass driver misfired, and instead of grazing your atmosphere, my shot hit your planet dead on, hitting it square in the middle of the large ocean.
Many of the dinosaurs perished from the initial shock wave, many more from the resulting mile-high tsunami. Most of the rest died in the long winter that followed.
The review board found the entire team guilty of negligence and sentenced us to live out the rest of our lives on your planet, face to face with the consequences of our actions. As humans measure time, that was 65 million years ago.
I’m so sorry.