United Therapeutics is collaborating with Varda Space Industries to test pharmaceuticals in outer space. Courtesy Varda Varda Space Industries, a startup that’s been pitching its ability to perform drug experiments in space, says it has signed up the pharmaceutical company United Therapeutics in what may be remembered as a notable step toward in-orbit manufacturing. The idea of building things in outer space for use on Earth has so far been explored mostly on board the International Space Station, and only in small-scale experiments backed by governments. But Varda, based in El Segundo, California, is now telling drug companies it has a practical, and repeatable, way to produce novel molecules in microgravity.  “This is the first commercial path to products made in space,” says Michael Reilly, Varda’s chief strategy officer. The scientific idea is that chemical mixtures have different properties under weightless conditions.…