OR Flew Too Close to the Sun
- Familiarity: I've used it once or twice and have initial impressions
- Fit: True to size
While this bivy is theoretically fantastic, it has a variety of practical failings that render it generally unpleasant to use.
Firstly, the zipper arrangement is simply ridiculous: six zippers each for the fly net and outer, for a total of twelve zippers that constantly get mixed up and caught on each other. I have never dealt with a shelter whose entrance was so difficult to manage. Of course, it's not unmanageable; a little wit and patience makes it functional. But are you really trying to by just 'functional'?
The purpose of the army of zippers is to allow the bivy to functional as a kind of XL raincoat, so that you can sit up and have a hole for your head and each arm. However, if you're using an inflatable sleeping pad with any decent loft (e.g. Thermarest Neoair) then you'll need some impressive core strength to sit up comfortably. And even if you do, the flex created by the pad will pull the arm holes and head hole open, defeating the purpose. The Interstellar's sombrero raincoat works in an empty bivy, and perhaps with a foam mat (I didn't try), but not with an inflatable mat.
This bivy is also incompatible with an inflatable mat, and indeed a four season bag, because there simply isn't enough interior volume. On 3" of mat, with decent bag loft, you'll be pressed against the top of the bivy. This isn't an issue in the Helium or Alpine bivies, because the entrance is at the head, but it's a deal breaker for the Interstellar because it means you have very little room to reach for the aforementioned tangle of zippers. Ultimately it renders this bivy extremely dysfunctional for a person using an inflatable mat and 30F or below bag.
Of course, the Interstellar has redeemable qualities in its breathability, weight, and easy of construction, but considering that these qualities are shared with OR's other bivies, the Black Diamond Spotlight, and several other designs, it seems like it's best to look at another model.
I'll be trading my Interstellar for an Alpine bivy. OR could improve this product by giving up on the elaborate zipper system and adding just a little more vertical space (for inflatable mats).