There was always something prolific, radical, and poetic about the late Sun Ra. His futuristic and provocative work as a multi-instrumentalist jazz maestro and bandleader of the Arkestra, which he formed in the mid-1950s, spoke volumes about the never-ending possibilities of sonic innovation. It’s an eclectic and influential spirit that has lived on with Sun Ra Arkestra since his death in 1993. Under the direction of Sun Ra collaborator and all-round genius Marshall Allen for the last two decades, the local ensemble will bring their cosmic avant-garde symphonies to the 40th Street Summer Series, presented by the University City District, The Rotunda, and the University of Pennsylvania. Kicking off tonight with the Arkestra and the fantastic, Dornetta Gary-led West Philly drill team Elegant Cavaliers, the free expanded 2011 music cycle will take place every fourth Saturday until September on the field behind the Walnut Street Free Library. Along with complimentary, first come-first served Rita’s Water Ice provided during performances, City Tap House at the University City Micro Center will offer special deals and outdoor eating in conjunction with the Summer Series—that’s burgers, hot dogs, grilled sausages and $3 Yards draughts, (plus other drink steals) while you soak in some modern tunes. Can’t check out the Arkestra at the two-hour inception? Then pick up the 20-disc box set The Eternal Myth Revealed Vol. 1, out July 18 on Transparency Records. Compiled with Sun Ra Archive Director Michael D. Anderson’s assistance, the collection will feature 400 rare tracks from 1933-1959 and a 100-page paperback. Seriously, get it. It’ll blow your mind. 40th and Walnut Sts. Field (Behind Walnut St Free Library), FREE, 6-8pm, All Ages –Annamarya Scaccia