AltCar Expo 2012, an exposition of the future of renewable energy and alternative transportation, takes place Friday and Saturday, September 28-29 at the Santa Monica Civic Auditorium. The event is free.

Leading sf writers and scientists will be there Saturday afternoon at 4:00 p.m. for “Mars and the Heart of Humanity: Ray Bradbury’s Million-Year Picnic,” a panel devoted to remembering Ray and discussing his favorite planet, Mars, “as it’s been imagined in the past, as it’s being discovered today and as it might eventually become.”

Appearing are Greg Bear, Hugo and Nebula award-winning author of over 40 books, including Hull Zero Three, Howard V. Hendrix, sf novelist, scholar and editor of Visions of Mars and The Mars Encyclopedia, and Charles Baker, Cruise, Entry, Decent and Landing Lead Mission Planner for JPL’s Curiosity Rover. Bradbury friend Bill Goodwin will moderate.

Of course, good luck getting there on Saturday if you’re not coming from a location west of the 405 freeway. Carmageddon II begins midnight Saturday, and for the next 48 hours they’re shutting down 10 miles of freeway on that side of LA to facilitate removal of a bridge in the Mulholland Pass.

People won’t need alternate cars that day, they’ll need alternate transporter booths.

[Thanks to John King Tarpinian for the story.]