HL-20: the mini-shuttle that almost was
NASA begins intensive work, including the construction of a full-sized test article, on the HL-20, a vehicle being considered for “assured access” to the space station NASA plans to build in the 1990s. HL-20 is based upon the scale-model unmanned BOR4 vehicle test-launched four times by the Soviet Union, and testing will get as far as NASA conducting simulations to determine seating and cargo placement. Despite the relatively recent Challenger disaster, the HL-20 project is quietly dropped in the early 1990s since no urgent need is seen on a widespread basis throughout NASA to phase out or replace the Space Shuttle. The design will be revived in the 21st century by Sierra Nevada Corproation as the proposed Dream Chaser vehicle.