The year was 2013. DARPA introduces the XS-1 concept, a reusable spaceplane dedicated to launch man’s (tiny) creations at the edge of space at costs cheaper than even conventional launches of our modern era. Or so it had claimed.
Fast forward to 2017, and DARPA has finally awarded the XS-1 project to none other than Boeing. This brings the project to its second phase, possibly building the first actual prototype in just two years.
Two Decades Long to Phase Two
The XS-1 was indeed first introduced in 2013. However, this was after several proposal failures made as early as the 80’s and 90’s. This means that single-stage-to-orbit (SSTO) vehicles were already conceptualized as early as the Space Shuttle’s first few years of active service.
So what is different today you ask? DARPA points out that current advancements in technologies finally made it possible to revive the concept. Since the original idea focused on a hypersonic (mach 5 to escape velocity) vehicle, the availability of updated “space-age” materials was perhaps the primary deciding factor. This is in addition to current enhanced navigation and systems monitoring with just about any type of vehicle or craft today.
Thus, the idea predates the recent accomplishments of the ISRO, SpaceX and Blue Origin by a rather long shot. This does not mean that the base idea is outdated, however, as we shall soon see how it differs completely from the literally cash burning behemoth that was the Space Shuttle.
Spaceplane? Not Space Shuttle?
Looking at its concept presentation, one might inevitably observe that the XS-1 is suspiciously similar to the Space Shuttle. It has launch reusability, is designed like a plane, can land on the ground like a plane, and is designed deploy payloads at a hind compartment. However, one must note that XS-1 is actually vastly different from the Space Shuttle for several very important reasons, such as:
- It is an SSTO. The Space Shuttle, while designed like a plane, was not built to launch on a single stage. As a one-stage spaceplane, the XS-1 is designed to launch at the edge of space using only its own boosters and fuel.
- It is designed for multiple launches over several days. No, we’re not talking about refurbishing its components for the better part of the year after a single launch. The XS-1 will launch and land and launch again, at lease once every single day.
- It is ultimately designed to reduce launch costs to just about $5 million ($3,000 per payload kg) per mission. Compare that to the average launch cost of a single Space Shuttle mission, which was $450 million ($20,000 per payload kg) as of 2011.
- It is made for significantly smaller, but multiple payloads of about 1,300~2,000 kilograms per launch. Even the Space Shuttle had a typical payload capacity of 20,000 kilograms to low-Earth-orbit (LEO), similar to current two-stage commercial rockets today.
Development and Competitive Prospects
With Boeing now set to bring the project to Phase 2, the next primary objective is to develop a working demonstration vehicle. The first test for a ground-based prootype is scheduled sometime in 2019, which will comprise of several feasibility objectives.
The most notable of these objectives, is the assessment of whether it is possible to fire up and use the designed engines for ten times over the course of ten days. If proven possible, the design would most likely be incorporated as the vehicles’s standard turnaround period. A fully launch-capable version of the XS-1 will then be developed a year after the tests, in 2020, for another full round of launch experiments.
While the primary impetus for the development of the XS-1 can be considerably ambiguous, the motivation to make space far more accessible than ever has never been this more pronounced. Sure, it has far less altruistic or even commercial objectives as it seems, but the concept itself is worth shaking the global think tank.