Smart-1 Saturday

Hope to see some of you Friday or Saturday night. As always, our schedule is shown at the top right of the Old Town Sidewalk Astronomers (OTASTRO) website http://www.otastro.org/

I've been receiving a lot of questions at work today about the European Space Agency's Smart-1 lunar orbiter's impact on the moon tomorrow night (Saturday, September 2) SO I typed this up for my colleagues, and thought I'd share it with you too.

It sort of coincides with our Monrovia Sidewalk Astronomy Saturday night, tho' it is highly unlikely that it can be seen from amateur telescopes. But we'll stay out a little later than usual just to view the moon at the designated time of 10:41 p.m. I'll bring some maps to hand out for those who want them. Friday night - gosh, that's tonight, we'll be in Pasadena 7ish - 10:00 p.m. mostly moon, and possibly a low Jupiter view.

The nine-day old waxing (or gibbous) moon will be visible throughout the late afternoon, will transit at mid-evening and set after midnight. Refer to the moon map linked below to find the craters I describe. One of the moon's most glorious sights, the large (100km/60 mile) diameter young crater Copernicus (area 31) is located midway between north and south on the sunny side of the terminator. Further south, the bright ejecta rays of 85km/53mile diameter even younger Tycho (area 64) are more and more brilliant as the moon nears full. Hitchhikers Guide to the Moon is my favorite lunar website. http://www.shallowsky.com/moon/hitchhiker.html

Meanwhile, over on the night side of the terminator, Smart-1 is preparing for its own termination. SMART-1, ESA's "Small Missions for Advanced Research in Technology", is about to end its exploration adventure after almost sixteen months of lunar science investigations.

Look on this ESA link to see an image of the moon at the nominal impact time (10:42 p.m. Pacific September 2. http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39942 You'll see bright craters Copernicus and Tycho center and south. The impact most likely won't be visible through anything but large ground or space telescopes, but amateurs everywhere will all be looking moonward anyway.

You can share these times with your friends around the world.....The expected impact time (07:41 CEST or 10:41 P.M. PST) will be good for big telescopes in South and Northwest Americas and Hawaii and possibly Australia. But if SMART-1 hits a hill on its previous pass, around 02:37 CEST on 3 September (5:37 p.m. PST Saturday night, before sunset) , then it can be observed from the Canary Islands and South America. If SMART-1 hits a hill on the pass on 2 September at 21:33 CEST, then telescopes in Continental Europe and Africa will have the advantage.

It travelled to the Moon using solar-electric propulsion and carried a battery of miniaturized instruments. As well as testing new technology, SMART-1 made the first comprehensive inventory of key chemical elements in the lunar surface.

If left on the course of its lunar orbit, SMART-1 would have naturally hit the Moon on 17 August 2006 on the lunar far side, not visible from Earth. A 2-week series of manoeuvres started on 19 June and concluded on 2 July allowed SMART-1 to adjust its orbit to avoid having the spacecraft intersect with the Moon at a disadvantageous time from the scientific point of view, and to obtain a useful small mission 'extension'.

On 3 September 2006 (Evening of Sept 2 here in California) the SMART-1 perilune, coinciding with the point of impact, will be on the lunar area called 'Lake of Excellence', located at mid-southern latitudes. This area is very interesting from the scientific point of view. It is a volcanic plain area surrounded by highlands.

At the time of impact, this area will be in the dark on the near-side of the Moon, just near the terminator - the line separating the lunar day-side from the night-side. The region will be shadowed from the Sun's direct rays, but it will be lit faintly by the light from the Earth - by earthshine. The spacecraft's orbit will take it over the region every five hours, getting one kilometer lower at each pass. From Earth, a Moon quarter will be visible at that time.

Jane Houston Jones
Senior Outreach Specialist, Cassini Program
JPL - 4800 Oak Grove Drive, MS 230-205
Pasadena, CA 91109 818-393-6435
jane.h.jones@jpl.nasa.gov
Cassini Saturn Observation Campaign
http://soc.jpl.nasa.gov/index.cfm