Rockoon is such an awesomely crazy word, and what it means is almost crazier still — a rocket that is launched not from the ground or an aircraft but from a balloon. This saves the launch vehicle from having to slog through the dense lower atmosphere, and is a lot cheaper than a big jet (a la Pegasus), but has two major problems: even the largest stratospheric balloons can’t carry very much, and they have absolutely no way of steering prior to ignition.
But the cheapness aspect was very attractive to some early rocket pioneers. Van Allen (yes, that Van Allen) spearheaded an effort to lift sounding rockets by balloon in order to increase the apogee they could reach. Van Allen and his team launched a number of rockoons for scientific and technological purposes in the 1940s and 1950s, and then the concept slowly faded as ground-based rockets became more powerful and abundant, driven by advances in ballistic missile technology, which of course has no use for a balloon-assisted launch.
But the concept never really went away, and every now and again, you hear of a company dabbling with it. JP Aerospace has been pursuing a particularly novel variant, where instead of an expendable stratospheric balloon, they would use a reusable wing-shaped balloon that could cycle up and down as a sort of intermediary stage. As part of that, they have made a few rockoon flights. Several universities have begun dabbling in them as well. Counterintuitively, as space technology has become more accessible, the market for very small rockets has grown. The immediate future, or at least a pretty big piece of it, seems to be full of nanosatellites, and these neither need nor can afford a big launch vehicle. Traditionally, they’ve hitched rides on the rockets used to launch big, conventional satellites, but the burgeoning market has led to new concepts for getting these little things to orbit. The ISS carries launchers that can spit out Cubesats, which are typically sent up as payload aboard Progress, Dragon, or Cygnus and then loaded into the launchers via the Kibo lab’s airlock. A recent PSLV launch carried a staggering 104 satellites, 96 of which were Cubesats — tripling the record for number of simultaneously launched satellites. And yet the market still demands more options, so lower cost launchers dedicated to the smallsat market have begun to appear.
One of the latest is Bloostar, the rather charmingly named rockoon concept from the Spanish company Zero2infinity. It’s an outgrowth of their existing work developing balloons for relatively low-cost flights to near space (called “Bloon”). Bloostar is a rockoon system with a unique, custom-built launch vehicle instead of the old sounding rockets of the original rockoons. And this week, it completed its first test flight, firing the engine for just a few seconds in a test of the ignition system and the navigation and telemetry systems. Later flights are expected to test a full-duration burn and see how high they can get it to go. 😉