[X] My Assistant

[fredk]

Spirit shot the night sky again on sol 632, but this time no sign of Phobos or Deimos.

This shot shows Orion. It's upside-down, for northern-hemisphere earthlings at least, but more fascinating is that the star trail direction differs markedly from what you see (anywhere!) on Earth, since Earth's and Mars' axes are well from parallel. It really is jarring to see, if you've ever shot star trails of Orion before!

This shot shows a patch of Gemini, though it's harder to recognize. That's Castor, brightest star along the bottom edge, halfway from centre to right edge. Pollux is just out of frame.

Any ideas what the goal is here, if not just to drain off some excess power?

Would it be feasible to do a real circumpolar-style star shot, showing arcs around an alien celestial pole? For spirit, it'd be Mars' south celestial pole, 15 or so degrees above the southern horizon. A navcam shot could be quite dramatic, with the ghostly outline of McCool/Ramon hills and the south rim of Gusev underneath the alien startrails.

I guess time is the problem - you'd need several minutes exposure at least to show arcs. But perhaps a series of 30 second shots, which could easily be combined digitally? Wishful thinking, perhaps, but then again if there's extra power to drain...

[Gonzz]

Since the rotation speed and direction are known could they use image editing software to correct the image?

[odave]

Yep - there's software out there now to de-rotate fields for alt-az platforms. The show stopper for star tracking, I think, would be if they can't image and move the PMA at the same time. I haven't had time to research that issue yet.

[hansvi]

Hello people, just joining in..

About the Nov 18 update, it says: "Mars is currently passing through a debris trail of Halley's comet, and Spirit is attempting to observe resulting meteor showers with the panoramic camera at night."

I was wondering why they would want to use the panoramic camera instead of the navigation camera. If you want to catch meteor storms, you want a large field of view instead of watching a small region and missing 99.9% of the action..

In fact, I think the Hazcams are best suited for this, with their wide angle lens. Unfortunately they're not pointing in the right direction..

Anyway, why do they "waste" time/energy/bandwidth with pancam images? There must be a reason, as I doubt a NASA engineer would ever read this and say "of course, I hadn't thought of that".

[dilo]

Welcome to the Forum, hansvi. I'm little disappointed too... I thought answer was related to the higher sensitivity of PanCam, but this isn't true (see previous post on this thread) and, considering also the higher focal ratio and the use of R2 filter for right images (with only 20nm bandpass), I cannot explain this choice!