Looking For LCROSS

by James MacWilliam, Sunshine Coast Centre

Thursday 9th October

In just 90 minutes time, NASA was to crash the lunar probe, LCROSS, into a permanently shadowed crater (Cabeous) at the Lunar South Pole. Actually, the upper stage of a Centaur rocket would hit the Moon first at 6 km per second followed 4 minutes later by the LCROSS probe itself. LCROSS was to fly through the plume sent up by the first impact and measure, hopefully, water vapour.

The impact time and site were carefully chosen to allow all the big scopes - Keck, CFH, Palomar, Hale, etc., in the western part of N. America to focus on the Moon with a barage of imagers, spectrum analysers, and the like... in the hope of securing both scientific proof of water on the Moon and providing a spectacle for the public.

The Result? Well, the jury is still out on that one, but it was great to know that we were watching the Lunar South Pole at the same time as most of the major observatories in western N. America!

My alarm went off at 3.00 am and I immediately checked the sky conditions. The sky was 80% cloud covered, but the Moon was in the clear sector. I made some breakfast and checked again at 3.30 am. The sky was clearing quickly so it was a green light to set up the scope in the backyard.

I gave my wife, Debra, the clear sky report at 3.45 am. Outside, at 4.00 am, I began aligning the ASGT mount - I didn't want the scope to drift too much when I was videoing the Moon at high power. I looked up and there was now 80% cloud cover again. The sky conditions were changing so rapidly it was hard to keep up. There was a low, fast moving cloud racing across the face of the Moon as we aimed our scopes skyward.

At the last minute, I realised the hand controller for the C8-ASGT was missing from its case! My cell phone showed 4.25 am, and I raced into the house trying to figure out how the HC could be missing? Finally, I found it in my backpack. I had taken it to London Drugs to look for an RS232 cable to connect to the PC. I dashed back to the scope, plugged in and did a "quick align". My cell phone showed 4.29 am - time was evaporating - as I slotted in a 7.5 mm E.P. with my Pentax Optio E30 (pocket digital) attached. I zeroed in on the South Polar Region at 271x but couldn't quite decide which crater was Cabeous...

The video was running as I again glanced at my cell phone and saw 4.32 am. The Impact had happened! I stared at the 3" screen on the back of the camera as the video continued to record. There was no sign of a plume, no flash or sign of any kind of movement. I had seen SMART-1 hit the Moon a couple of years ago - it was the briefest fleck of light - so I expected something more. I continued to video the impact area hoping a plume might develop but I later learned that even the 200" Hale Telescope saw nothing!

Finally, at around 4.45 am, I slewed away from the Moon - Orion was calling. I split the Trapezium for the first time with a C8. It was the biggest view of the Trapezium I've had and I had to remind myself the cloud in the FOV was Hydrogen and not the low, thin cloud in the sky above me. I slewed over to Mars and found a small squidgy yellow blob. I went back to the Moon and shot some video of mountains and craters near the terminator.

I Looked up once more at the Moon around 5.45 am and thought to myself, we came, we saw, errr, nothing! But, if a plume had developed, if it had been front page headlines the next day, how mad would we have been if we had missed it? I was glad to be pointing my scope along with the Hale, the Keck, and the Canada/France/Hawaii Telescope at the Moon!

Author: 
walter.macdonald2@gmail.com
Last modified: 
Monday, January 5, 2015 - 3:42pm