Danger Zone

Danger Zone is an episode of Angry Birds Space featuring 30 extremely challenging — brainteaser-like — levels. The level numbering is "D-1 " through "D-30", implying that Danger Zone is a non-sequential episode. The background of the Danger Zone looks like a space mine field owned by the pigs due to the fact that the mines have Pig Snouts on them. The Danger Zones has planets from Pig Bang, Cold Cuts, and Fry Me to the Moon, as well as the crystal mushrooms from Cold Cuts and Fry Me to the Moon, which still give you 3000 points. In the level selection screen, small mines with no pig snouts can be seen. In addition, one of the small mines can also be presented as a Special Item Bubble when players get 3 stars on all the levels in the Danger Zone.

Rovio's Description
The following is from Rovio's blog post:

"Think you can defeat THE DANGER ZONE? This special episode is filled with 30 of the most difficult Angry Birds levels EVER constructed -- we let our level designers go crazy with these ones, and they came up with some brain-wracking levels. Even some of us here at Rovio HQ, where we consider ourselves to be expert pig-poppers, have found ourselves sweating in The Danger Zone!

In other words: this area is for experts only! Think you can master it?

Note: we're working on bringing the Danger Zone to as many platforms as possible in the future, so stay tuned!"

For platforms using in-app purchases, the first level of Danger Zone is available as a free trial. PC users can access Danger Zone after passing all 30 levels of Pig Bang.

Levels
From Rovio's Description, this episode is very hard. It contains some hard level such as D-3, D-4, D-5 and D-25, harder such as D-1, D-14, D-15, D-16, D-20, D-21 and D-26, there are six very hard levels: D-2, D-9, D-12, D-23, D-27 and D-28. Level D-10 and D-30 are insanely hard. But there are some easy levels: D-7, D-8, D-11, D-17, D-18 and D-19.
 * Easiest level: Level D-7
 * Hardest level: Level D-10 and Level D-30

Trivia

 * The ending cut-scene used to has bird sounds when you clear a level. It has Super Red Bird's launch sound instead in later update.
 * The gravitational fields in Danger Zone are red, instead of blue like in other episodes.
 * This is the first episode that can purchase before playing.
 * This is the only episode that cannot unlock for free.