DARPA pushing new effort with Experimental Spaceplane, XS-1

by Chris Gebhardt

Citing increasing U.S. launch costs and the “fleeing” of commercial customers to foreign launch service providers, the Defense Advanced Research Projects Agency (DARPA) is continuing to push a bold strategy tied to a new, reusable spaceplane that the Agency envisions flying 10 times in 10 days for a cost of less than $5 million USD per flight.

The issue:

As defined by DARPA, the “Dramatic growth in U.S. launch costs since [the] early 1990s is driving much larger growth in space system costs.”

As part of DARPA’s “Experimental Spaceplane (XS-1): Aiming to Reduce the Time to Space and Cost to Space by Orders of Magnitude” overview (video and materials in L2), the program cites an annual DoD (Department of Defense) launch cost in excess of $3 billion USD, with small launches now cited as greater than $50 million USD each.

The presentation also notes the cost and flight rate of the current U.S. launch systems certified to carry out launch operations for the U.S. Federal Government.

2016-07-11-134829According to DARPA’s presentation, the Pegasus, Minotaur, and Antares launch vehicles only fly one DoD mission per year at a cost of ~$55 million USD per flight.

SpaceX’s Falcon 9 currently performs ~3-6 DoD missions per year at a contract price equal to or greater than $54 million USD per flight.

DARPA claims the price per flight then jumps for United Launch Alliance’s (ULA’s) Atlas V and Delta IV launch vehicle families, which – they claim – currently perform about 8 DoD flights per year for a cost per flight in excess of $400 million USD.

However, those numbers have been strangely inflated, as ULA’s own published figures note the average price of a mission, accounting for all current firm contracts for Atlas and Delta launch services, is actually $225 million. This includes all missions, Department of Defense (DoD), NASA, commercial, Atlas V 401 through Delta IV Heavy. The full price for a lower-end mission utilizing the Atlas V is $164 million.

While this pricing difference between SpaceX and ULA is well known and led to a rather public address of the issue within the U.S. Congress recently, DARPA also cites the increased production costs of satellites.

Specifically, the XS-1 presentation notes that a BLK I GPS satellite cost $43 million USD in 1990 compared to a BLK III GPS satellite cost of greater than $250 million USD today – a $170.96 million USD difference when adjusted for inflation.

“We’re living in very exciting times in the launch industry, with many new commercial entrants – and for the first time, reusable space plane concepts are starting to be taken seriously,” noted Jess Sponable, Program Manager at DARPA/TTO during a video presentation.

“It’s hard to ignore flying (and returning) hardware, so congratulations to SpaceX and Blue Origin. I anticipate more flying hardware (milestones) and I look forward to seeing it.”

DARPA’s solution – the XS-1 spaceplane:

DARPA’s solution to this issue is a new, reusable spaceplane called Experimental Spaceplane 1 (XS-1).

2016-07-11-125234Citing a “look back to the past”, Mr. Sponable cited previous attempts to create alternative reusuable spaceplanes – ranging back as far as World War II’s German Sanger concept, through to the Space Shuttle and even the X-33 effort that was to result in the VentureStar before the program’s demise.

“It proved to be a difficult challenge, with many successes and many failures along the way. (The likes of) the X-33 pushed the technology of reusable space flight,” added Mr. Sponable, adding NASA and the Air Force’s advances have directly helped not only SpaceX and Blue Origin, but also the “Technical Readiness Level” for reusable space lift.

With a TRL of around 5, this rating is much higher than when the X-33 was being developed, with – as noted by DARPA – immature technology. The X-33 development process began with a TRL level of 3.

As such, DARPA believes the time is right for a renewed effort, one that began in 2013/14, but is now being ramped up through a solicitation process, allowing for several industry concepts to be created.

2016-07-13-152645Per the requirements, the winged craft, according to DARPA’s vision, would be capable of performing 10 flights in 10 days, with a payload capacity greater than 3,000 lbs for a cost of less than $5 million USD per flight.

However, Mr. Sponable added that the winning concept wouldn’t necessarily have to be a winged vehicle, claiming they will listen to what the industry think is the best methord. Although he did intimate that “aircraft like” operations point to a lifting body vehicle being the aim.

According to the DARPA presentation, the XS-1 project carries four prioritized goals: the design of a reusable booster system with launch costs traceable to <$5M/flight; to fly the booster 10 times in 10 days; to demonstrate an immediate payload to orbit capability with cost traceability to the Operational System; and to enable routine, low-cost space access.

2016-07-13-174952Each of these four prioritized goals carries a test objective and a test threshold.

For a reusable booster with a cost per flight of less than $5 million USD, DARPA has set a test objective that XS-1 be able to transport equal to or greater than 3,000 lbs to a 100 nmi reference orbit inclined 90 degrees.

The threshold of this objective currently stands at an identical payload capacity to a 100 nmi reference orbit inclined 28.5 degrees.

For the flight rate goal, DARPA’s stated test objective is to achieve 10 flights in 10 consecutive days – even when weather, range, and emergency delays are accounted for (threshold).

For an immediate demonstration of a payload to orbit capability, the objective is to be able to carry equal to or greater than 1,500 lbs to a 100 nmi orbit inclined 28.5 degrees due east, with a threshold payload of equal to or greater than 900 lbs to the same target orbit parameters.

2016-07-13-165138To enable this routine access to space, DARPA hopes to “fly the XS-1 to Mach 10+ at least once, and stage at high Mach to minimize the size and cost of the upper stage, “ with a stated developmental threshold for this at Mach 3+ travelling speeds and Mach 2+ staging speeds.

While DARPA’s name for this project implies a plane or Space Shuttle-like design, the Agency is actually open to several design options for the commercial field, with the presentation containing different notional designs for the XS-1 from Boeing, Masten, and Northrop Grumman – among others.

Moreover, DARPA notes that the XS-1 could be a winged or unwinged vehicle. It could also be a payload carriage craft.

Given the broad range of potential designs, XS-1 could be a horizontal launch/horizontal land vehicle, a vertical launch/horizontal land vehicle, or a vertical launch/vertical land vehicle.

It could launch from the ground, air, or sea barge and could either land downrange or return to land at its launch site.

2016-07-13-153930Its Thermal Protection System could be metallic, composite, active, passive, or a hybrid system.

Regardless, the one development aspect DARPA is specific about in its presentation is that the XS-1 propulsion system must already be mature enough to enable flight testing No Later Than 2020.

DARPA also envisions the XS-1 as a craft capable of utilizing a clean pad with a minimally-staffed flights ops control center using a fully automated ops, propellant loading, and fluid loading system.

Development timeline and call for proposals:

Given DARPA’s desire to reduce the DoD launch market cost and be a competitor in the proliferating commercial launch market, the proposed schedule for development is quite compressed.

According to the XS-1 presentation, DARPA is already in Phase I of XS-1 development – and has been since the fourth quarter of FY 2014 (July-September 2014).

2016-07-13-164707Phase 1, which is currently tapering to its end by 30 September 2016, is the system design and risk reduction phase of development, which is now transitioning to Phases 2 and 3: full and open solicitation and development of the XS-1.

Under Phases 2/3, a Call For Proposals will be released around October 2016 – following the solitication release in May – with design review continuing through the second quarter of FY 2017 (January-March 2017).

DARPA – armed with $140m of specific funding for a public and private partnership – expects 25 concepts to be evaluated, according to Mr. Sponable.

A Critical Design Review is currently targeted for the first quarter of FY 2018 (October-December 2017) before the project moves on toward Flight Tests in the fourth quarter of FY 2019 (July-September 2019) through the first quarter of FY 2020 (October-December 2019).

2016-07-13-175431Launch site design would take place throughout FY 2017, with launch site construction taking place in FY 2018 and the first part of FY 2019.

Under this development schedule, DARPA envisions the XS-1 being ready for commercial transportation operations at the beginning of the third quarter of FY 2020 (April-June 2020).

At this time, DARPA anticipates to award the XS-1 contract to one provider only.

Moreover, while development will be a public-private partnership, DARPA’s intention to “directly transition the XS-1 to the commercial sector” is a critical aspect of the program

According to the presentation, “To facilitate commercialization, DARPA wants to transfer title of the XS-1 vehicle to industry, but industry needs to offer a plan that provides ‘consideration in kind’ justifying transfer of title.”

To this end, DARPA states that each proposal for development should address such commercial planning elements as: understanding of the current and projected market demands as well as “core customer needs by market segment” and how each company’s XS-1 design will address these needs.

2016-07-13-170728Crucial to this plan, DARPA is also requesting that each proposal specifically address the “competitiveness of existing vehicles and expected future vehicles.”

However, following studies, DARPA believe the commerical interest is high, with the results of how XS-1 may fit into the competitive market as “surprising”, according to Mr. Sponable, especially with the new constellations of satellites that are being proposed.

XS-1 would be able to provide a speedy launch of such constellations, with the studies showing the vehicle could launch 100 small satellites in 10 days for as little as $50m, compared to $500m on a Delta IV-H (although Mr. Sponable’s use of DARPA’s inflated cost estimates for the ULA rockets pour some cold water on his example).

2016-07-13-171736“A simplistic example is we could launch a constellation of 100 satellites on a Delta IV-H or we could spread them out 10 or more times on the XS-1 over 10 days,” added Mr. Sponable.

“On the Detla IV scenario, a great deal of risk is accepted by launching so many satellites at once. In fact, a customer may be betting their company on a successful launch. The XS-1 scenario is far less risky and allows for a far greater insertion of the satellites into orbital planes.”

The launch on demand capability of XS-1 – it was claimed – could prove to be a game changer for the commercial and military markets.

(Images via DARPA, US Air Force, Masten Space Systems, NASA and Derrick Stamos for L2).

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