Dream Chaser

Dream Chaser Orbital Spacecraft
Dream Chaser Flight Vehicle
Description
Role:	Part of NASA's Commercial Crew Program to supply crew and cargo to the International Space Station
Crew:	Up to 7[1][2]
Dimensions[3]
Length:	9.0 m	29.5 ft
Wing Span:	7.0 m	22.9 ft
Volume:	16.0 m3	565 cu ft
Mass:	11,300 kg	25,000 lb[4]
Performance
Endurance:	At least 210 days[5]
Re-entry:	Less than 1.5 g[4]

The Dream Chaser is a reusable crewed suborbital and orbital^[6] vertical-takeoff, horizontal-landing (VTHL) lifting-body spaceplane being developed by Sierra Nevada Corporation (SNC) Space Systems. The Dream Chaser is designed to carry up to seven people to and from low Earth orbit. The vehicle will launch vertically on an Atlas V rocket and land horizontally automatically on conventional runways.^[1]

Program objectives

The primary Dream Chaser Space System mission is to provide NASA with a safe, reliable commercially-operated transportation service for crew and cargo to the International Space Station (ISS) and back to Earth. Future Dream Chaser missions potentially include delivering crew and cargo to other orbiting facilities—including a European orbital facility after the ISS is decommissioned in 2024^[7] —or functioning as a short term independent orbiting laboratory for other government agencies or commercial entities, as well as potential orbital space tourism.^[8]

Design

Dream Chaser is a reusable composite spacecraft designed to carry from two to seven people and/or cargo to orbital destinations such as the International Space Station.^[9] It will have a built-in launch escape system^[10] and can fly autonomously if needed.^[4] It can use any suitable launch vehicle but is planned to be launched on a human-rated Atlas V 402 rocket.^[4][11] The vehicle will be able to return from space by gliding (typically experiencing less than 1.5 g on re-entry) and landing on any airport runway that handles commercial air traffic.^[8][12] Its reaction control system thrusters burn ethanol-based fuel,^[4][8] which is not an explosively volatile material, allowing the Dream Chaser to be handled immediately after landing, unlike the Space Shuttle.^[4] Its thermal protection system (TPS) is an ablative tile created by NASA's Ames Research Center that would be replaced as a large group rather than tile by tile, and would only need to be replaced after several flights.^[4] There are plans to build a fleet of Dream Chasers.^[8]

Rocket engines

On-orbit propulsion of the Dream Chaser is provided by twin hybrid rocket engines. The hybrid rocket motors are fueled with hydroxyl-terminated polybutadiene (HTPB) and nitrous oxide, or more simply put, "rubber and laughing gas".^[10] These two substances are both non-toxic and easily stored, making them safer than liquid rocket fuels. Unlike solid rockets, Dream Chaser's hybrid fuel system would allow the motor to stop and start repeatedly, and be throttleable. SNC Space Systems is also developing a similar hybrid rocket for Virgin Galactic's SpaceShipTwo.^[10]

As of December 2012, Sierra Nevada has over ten years of development heritage in its hybrid rocket propulsion technology for Dream Chaser, has done over 300 hybrid rocket firings, and developed the rocket engine for the first private rocket to space, SpaceShipOne which won the Ansari X-Prize in 2004.^[13]

Engine testing

Sierra Nevada completed an initial test phase on the Dream Chaser rocket engine in 2010, under the CCDev1 program, including three successful test firings on a single hybrid motor in a single day.^[14]

A second phase of testing began in June 2013, with a motor firing and ignition test in order to validate the newly modified test stand., as a start to the Commercial Crew Integrated Capability (CCiCap) contract test phase. Other tests will be completed summer 2013.^[14]

History

An artist's impression of the X-20 Dyna-Soar being launched using a Titan booster, with large fins added to the Titan's first stage.

The historical antecedents of the Dream Chaser go back over 50 years in the US; with the 1957 X-20 Dyna-Soar concept and the 1966 Northrop M2-F2 and Martin X-23 PRIME lifting bodies.^[15][16] Its design is derived from NASA's 1980 HL-20 lifting body design which was itself similar to the 1980's Soviet BOR-4, which in turn was considered by NASA engineers as influenced by the late 1960s HL-10,^[17] and Soviet Mikoyan-Gurevich MiG-105 military spaceplane concept,^[18] a spaceplane studied as a means to develop a Soviet counterpart to the US's X-20 Dyna-Soar.^[19]

The name "Dream Chaser" has been used for two separate space vehicles. One, planned to be an orbital vehicle based on the NASA HL-20, originated at SpaceDev when Jim Benson was still there. The second, a suborbital vehicle, was the result of Jim Benson having reused the name when he formed the Benson Space Company for the purposes of space tourism.^[18]

The Dream Chaser was publicly announced on 20 September 2004 as a candidate for NASA's Vision for Space Exploration^{[citation needed]} and later Commercial Orbital Transportation Services Program (COTS).

When the Dream Chaser was not selected under Phase 1 of the COTS Program, SpaceDev founder Jim Benson stepped down as Chairman of SpaceDev and started Benson Space Company to pursue the development of the Dream Chaser.^[20] In April 2007, SpaceDev announced that it had partnered with the United Launch Alliance to pursue the possibility of utilizing the Atlas V booster rocket as the Dream Chaser's launch vehicle.^[21] In June 2007, SpaceDev signed a Space Act agreement with NASA.^[22]

About two weeks after Benson's death, SpaceDev agreed to be acquired by Sierra Nevada Corporation on 21 October 2008 for $38 million.^[23] On 1 February 2010, Sierra Nevada Corporation was awarded $20 million in seed money under NASA’s Commercial Crew Development (CCDev) phase 1 program for the development of the Dream Chaser.^[24][25] Of the $50 million awarded by the CCDev program, Dream Chaser's award represented the largest share of the funds. SNC completed the four planned milestones on time which included program implementation plans, manufacturing readiness capability, hybrid rocket test fires, and the preliminary structure design.^[26] Further initial Dream Chaser tests included the drop test of a 15% scaled version at the NASA Dryden Flight Research Center.^[27] The 5-foot-long (1.52 meters) model was dropped from 14,000 feet (4,300 m) to test flight stability and collect aerodynamic data for flight control surfaces.^[27]

For the CCDev phase 2 solicitation by NASA in October 2010, Sierra Nevada proposed extensions of Dream Chaser spaceplane technology. According to head of Sierra Nevada Space Systems Mark Sirangelo, the cost of completing the Dream Chaser should be less than $1 billion.^[2][28]

On 18 April 2011, NASA awarded nearly $270 million in funding for CCDev 2, including $80 million to Sierra Nevada Corporation for Dream Chaser.^[29] Since then, nearly a dozen further milestones have been completed under that Space Act Agreement. Some of these milestones included testing of the airfoil fin shape, integrated flight software and hardware, landing gear, and a full-scale captive carry flight test.^[30][31]

On 3 August 2012, NASA announced the award of $212.5 million to Sierra Nevada Corporation to continue work on the Dream Chaser under the Commercial Crew Integrated Capability (CCiCAP) Program.^[32]

In December 2013, the German Aerospace Center (DLR) announced a funded study to investigate ways in which Europe might take advantage of the Dream Chaser crewed spaceplane technology. Named the DC4EU (Dream Chaser for European Utilization), the project will study using it for sending crews and cargo to the ISS and on missions not involving the ISS, particularly in orbits of substantially greater altitude than the ISS can reach.^[33] In January 2014, the European Space Agency (ESA) agreed to be a partner on the DC4EU project, and will also investigate whether the Dream Chaser can utilize ESA avionics and docking mechanisms. ESA will also study launching options for the "Europeanized" Dream Chaser, particularly whether it can be launched within the Ariane 5's large aerodynamic cargo fairing – or, like the Atlas V, without it. In order to fit within the fairing, the Dream Chaser's wing length will have to be reduced slightly, which is thought to be easier than going through a full aerodynamic test program to evaluate and prove it along with the Ariane for flight without the fairing.^[34]

In late January 2014, it was announced that the Dream Chaser orbital test vehicle was under contract to be launched on an initial orbital test flight, using an Atlas V rocket, from Kennedy Space Center in November 2016. This is a privately arranged commercial agreement, and is funded directly by Sierra Nevada and is not a part of any existing NASA contract.^[35]

Development progress

The completed craft on the day of its initial captive carry test

On 24 June 2011 SNC announced it had achieved two critical milestones for NASA's CCDev program. The first was a Systems Requirement Review (SRR), where SNC validated their requirements based on NASA’s draft Commercial Crew Program Requirements. The SRR was successfully completed on 1 June 2011 with participation from NASA and SNC industry partners. The second milestone was a review of the improved airfoil fin shape for Dream Chaser used to aid its control through the atmosphere. Testing in a wind tunnel and computational fluid dynamics analyses allowed the fin selection to pass the NASA milestone.^[36]

As of October 2011, Sierra Nevada Corp had completed four of the 13 milestones set out in the CCDev Agreement.^[37] The most recent milestones accomplished include: a System Requirements Review, a new cockpit simulator, finalizing the tip fin airfoil design and most recently,^[38] a Vehicle Avionics Integration Laboratory (VAIL), which will be used to test Dream Chaser computers and electronics in simulated space mission scenarios.^[37]

By February 2012, Sierra Nevada Corporation stated that it had completed the assembly and delivery of the primary structure of the first Dream Chaser flight test vehicle. With this, SNC completed all 11 of its CCDev milestones that were scheduled up to that point. SNC stated in a press release that it was "...on time and on budget."^[39]

On 24 April 2012 Sierra Nevada Corporation announced the successful completion of wind tunnel testing of a scale model of the Dream Chaser vehicle.^[40]

On 12 June 2012 SNC announced the commemoration of its fifth year as a NASA Langley partner in the design and development of Dream Chaser.^[41] Together with ULA, the NASA/SNC team performed buffet tests on the Dream Chaser and Atlas V stack. To date, the Langley/SNC team has worked on aerodynamic and aerothermal analysis of Dream Chaser, as well as guidance, navigation and control systems.^[41]

On 11 July 2012 SNC announced that they successfully completed testing of the nose landing gear for Dream Chaser.^[42] This milestone evaluated the impact to the landing gear during simulated approach and landing tests as well as the impact of future orbital flights. The main landing gear was tested in a similar way in February 2012. The nose gear landing test was the last milestone to be completed before the free flight approach and landing tests scheduled for later in 2012.^[42]

In August 2012, SNC completed CCiCap Milestone 1, or the ‘Program Implementation Plan Review’. This included creating a plan for implementing design, development, testing, and evaluation activities through the duration of CCiCap funding.^[43]

By October 2012 the "Integrated System Baseline Review", or CCiCap Milestone 2, had been completed. This review demonstrated the maturity of the Dream Chaser Space System as well as the integration and support of the Atlas V launch vehicle, mission systems, and ground systems.^[43]

On 30 January 2013 SNC announced a new partnership with Lockheed Martin. Under the agreement, SNC will pay Lockheed Martin $10 million to build the second airframe at its Michoud facility in New Orleans, Louisiana. This second airframe is slated to be the first orbital test vehicle, with orbital flight testing planned to begin within the next two years.^[44] In January 2014, SNC announced they had signed a launch contract to fly the first orbital test vehicle on a robotically-controlled orbital test flight in November 2016.^[35]

In January 2013, Sierra Nevada also announced that the second captive carry and first unpowered drop test of Dream Chaser would take place at Edwards Air Force Base, California in March 2013. The spaceplane release would occur at 3,700 metres (12,000 ft) altitude and would be followed by an autonomous robotic landing.^[44][45]

On 13 March 2013, NASA announced that former space shuttle commander Lee Archambault was leaving the agency in order to join SNC. Archambault, a former combat pilot and 15-year NASA veteran who flew on Atlantis and Discovery, will work on the Dream Chaser program as a systems engineer and test pilot.^[46][47]

On 29 April 2013, Virgin Galactic's SpaceShipTwo sub-orbital vehicle was propelled on its first ever powered flight by SNC’s Hybrid Rocket Motor. SNC manufactures the main oxidizer valve and the hybrid rocket motor, plus the nitrous oxide dump and pressurization system control valves. The hybrid rocket motor and oxidizer valve system are manufactured at an SNC facility in Poway, California, where motors for both Space Ship Two and Dream Chaser are produced.^[48]

Flight test program

In May 2013, The Dream Chaser Engineering Test Article (ETA) was shipped to the Dryden Flight Research Center in California for a series of ground tests and aerodynamic flight tests.^[49] This move to Dryden came about a year after a captive carry test that was conducted near the Rocky Mountain Metropolitan Airport on 29 May 2012. During that test, an Erickson Skycrane was used to lift the Dream Chaser to better determine its aerodynamic properties.^[50] "The testing at Dryden will include tow, captive-carry and free-flight tests of the Dream Chaser. A truck will tow the vehicle down a runway to validate performance of the nose strut, brakes and tires. The captive-carry flights will further examine the loads the vehicle will encounter during flight and test the performance and flutter of the vehicle up to release from an Erickson Skycrane helicopter. The free-flight tests are designed to validate the Dream Chaser's aerodynamics as well as test the flight control surfaces to verify flight characteristics for approach, flare and landing."^[51] A second captive carry flight test was completed on 22 August 2013.^[52]

On 26 October 2013, the first free-flight occurred. The test vehicle was released from the "skycrane" helicopter, and flew the correct flightpath to touchdown less than a minute later. Just prior to landing, the left main landing gear failed to deploy resulting in a crash landing.^[53] In a press teleconference a short while later, Mark Sirangelo, corporate vice president of Sierra Nevada, told reporters that the view of the ETA was obscured by the dust as it skidded off the runway, but that the vehicle was found upright, with the crew compartment intact, and all systems inside still in working order. Sierra Nevada corporation engineers do not believe that the ETA flipped over.^[54][55]

The first two Dream Chasers — the ETA and the Flight Test Article (FTA) — have been given internal and external names, with some sources reporting that the ETA will be named Eagle.^[49]

Dream Chaser model being tested at NASA Langley

An initial orbital test flight of the Dream Chaser orbital test vehicle is planned for 1 November 2016, launching on an Atlas V rocket from Kennedy Space Center.^[35]

Technology partners

The following organizations have been named as technology partners:

• Boeing Phantom Works – construction of some early test articles^[12]
• Charles Stark Draper Laboratory – Guidance, Navigation and Control^[12]
• Aerojet – reaction control system technology^[12]
• University of Colorado – human-rating^[12]
• AdamWorks – composites^[12]
• MDA – systems engineering^[12]
• Lockheed Martin – airframe construction and human rating of the spaceplane^[44][45]

See also

• BOR-4
• BOR-5
• Mikoyan-Gurevich MiG-105
• Boeing X-20 Dyna-Soar
• Boeing X-37
• HL-20 Personnel Launch System
• Commercial Crew Development
• Private spaceflight
• Skylon
• Spaceplane

References

External links

Wikimedia Commons has media related to Dream Chaser.

• Sierra Nevada Corporation Space Systems web site
• SNC Space Systems' Dream Chaser page
• SpaceDev web site
• United Launch Alliance web site
• CG rendering of Dream Chaser servicing ISS
• Video animation — SpaceDev International Lunar Observatory Human Servicing Mission concept

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