I scream, you scream, we all scream for reconstituted dairy dust—I think that's what they say? Certainly it would be an appropriate thing to say now, as we prepare to celebrate the 50th anniversary of the Apollo 11 moon landing (July 20th, 1969) and simultaneously weather a harrowing heat wave. The Apollo missions, you see, gave us freeze-dried ice cream, an unmelting space food that turns out to be absolutely unsuitable for space travel but maybe pretty okay for scorching summer days. If you're willing to set aside the winning properties of ice cream classic and hang all your hopes on heat resistance, that is.

Anyway, in honor of the impending astronautical achievement, we remember: Freeze-dried ice cream, the space dessert that maybe never even went to space. (Not including that time Stephen Colbert sent it up in a balloon.)

When NASA first began packing people onto space flights, they lacked clarity about what zero gravity might mean for the human digestive process. John Glenn enjoyed the first recorded space snack—a tube of apple sauce—in 1962, but the astronauts needed heartier options. Without the ability to freeze ingredients on early missions, all food needed to be dehydrated, or freeze-dried, or heat-treated so it could survive at room temperature. NASA enlisted the Whirlpool Corporation to help with mission-ready menus, which is apparently how we figured out how to freeze-dry ice cream: Take a slab of the dessert and freeze it to -15 degrees Celsius, then vaporize the ice crystals and siphon them off, until the product eventually becomes a kind of crispy, foamy brick.

If you let it sit in your mouth for a few minutes, rather than just crunching through the "treat" as if it were a cookie, this sci-fi wafer allegedly takes on a creamy texture reminiscent of its primal state. Allegedly.

But whether or not astronauts have actually experienced its perplexing mouthfeel while peering down on our chaotic rock remains murky. Vickie Kloeris, a food scientist who has long worked with NASA and with the International Space Station, told NPR in 2011 that the ice cream flew only once, during the Apollo program. And indeed, vanilla ice cream does appear on the menu for the 1968 Apollo 7 mission, per a contemporaneous press release, but there's no clear indication that the dessert definitively made it on board. Still, that's the flight classically associated with this elusive snack.

Walter Cunningham, the only member of the Apollo 7 crew still alive today, remembers buying the stuff at the Johnson Space Center gift shop in Houston—"not bad, but after a few times you realize you don't really need any more of it"—but insists he has no memory of eating astronaut ice cream on the spacecraft. He vividly remembers the chocolate pudding and the bacon bits, but not the ice cream chunk. Mission transcripts also make no mention of the dessert, and as National Air and Space Museum Curator Jennifer Levasseur told Vox:

It's very likely it never flew. It probably got made, tested on the ground, and rejected. They do always get to try things in advance, and they probably thought it was as horrible as it actually is when you buy it in the gift shop.

Not accounting for taste, the reason freeze-dried ice cream has mostly been confined to museum gift shops (courtesy Astronaut Foods) has more to do with its consistency. Were we to rocket it into the final frontier, floating chalk crumbs would bedevil astronauts by sneaking into their eyeballs and electronics.

Since the Sixties, though, science has figured out how to get a freezer into space. In 2006, the Atlantis shuttle flew the GLACIER, stocked with chocolate-swirled Blue Bell cups, to the International Space Station. The ISS got a fresh batch in 2012.

Astronaut ice cream, meanwhile, has found an audience among backpackers, preppers, and soldiers in hot climes like Afghanistan, where the product's refusal to melt may top the original's cool and refreshing properties. Maybe, when temps rocket past 100 this weekend, you will appreciate your freeze-dried milk fat ration a little bit more. Find it at a museum gift shop near you.