Istra - An air-breathing ballistic space transport vehicle for Europe

A new concept for Istra, a reusable space transport vehicle to succeed Ariane, is discussed. The concept involves a hydrogen ramjet combined with a reusable one-and-one-half stage, ballistic space transport vehicle which takes off and lands vertically and utilizes liquid hydrogen and liquid oxygen as fuel. The results for Istra include: a 15.4 Mg working load in low circular orbit at 155 Mg starting mass, with about a 10 percent working load ratio; a 56 percent fuel saving and a 44 percent saving in dry mass compared to two-stage rocket concepts. These results are compared to those for recent European space transport vehicle concepts.