Dream Chaser

This article is about the Sierra Nevada Corporation (SNC) spaceplane. For other uses, see Dream Chasers.
Dream Chaser Cargo System
Manufacturer Sierra Nevada Corporation
Country of origin United States
Operator NASA
Applications ISS resupply
Specifications
Spacecraft type Unmanned cargo vehicle
Payload capacity

5,000 kg (11,000 lb) pressurized,

500 kg (1,100 lb) unpressurized
Production
Status In development

The Dream Chaser Cargo System is an American reusable automated cargo lifting-body spaceplane being developed by Sierra Nevada Corporation (SNC) Space Systems. The Dream Chaser is designed to resupply the International Space Station with both pressurized and unpressurized cargo. The vehicle would launch vertically on an Atlas V, Ariane 5 or Falcon Heavy rocket [1] and land horizontally autonomously on conventional runways.[2] Further development of the spaceplane includes a manned version Dream Chaser Space System, which is capable to carry up to seven people to and from low Earth orbit.

Design

Rocket engines

On-orbit propulsion of the Dream Chaser was supposed to be provided by twin hybrid rocket engines fueled with non-toxic and storable hydroxyl-terminated polybutadiene (HTPB) and nitrous oxide.[3] Unlike solid rockets, Dream Chaser's hybrid fuel system would allow the motor to stop and start repeatedly, and be throttleable. SNC Space Systems was also developing a similar hybrid rocket, RocketMotor Two, for Virgin Galactic's SpaceShipTwo,[3] as a subcontractor to Scaled Composites. In May 2014 their involvement in the program ended, after Virgin Galactic elected to replace SNC's version of RocketMotorTwo, powered by HTBD rubber fuel, with its own internally developed hybrid motor using a polyamide plastic fuel, while continuing to use the same nitrous oxide oxidizer.[4]

However, after the acquisition of Orbitec LLC in July 2014, Sierra Nevada Corporation announced a major change to the propulsion system. The hybrid rocket engine design was dropped, in favor of a cluster of Orbitec's Vortex engines. The new engines would use propane and nitrous oxide as propellants.[5]

Dream Chaser Space System

Artist's conception of the Dream Chaser Space System in the launch configuration

Dream Chaser Space System is a planned human-rated version designed to carry from two to seven people and/or cargo to orbital destinations such as the International Space Station.[6] It would have a built-in launch escape system[3] and could fly autonomously if needed.[7] It could use any suitable launch vehicle but is planned to be launched on a human-rated Atlas V 412 rocket.[7][8] The vehicle would 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.[9][10] Its reaction control system thrusters burn ethanol-based fuel,[7][9] which is not an explosively volatile material, nor toxic like hydrazine, allowing the Dream Chaser to be handled immediately after landing, unlike the Space Shuttle.[7] 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.[7]

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.[11][12] Its design is derived from NASA's 1990 HL-20 lifting body design which was itself similar to the 1980s Soviet BOR-4, which in turn was considered by NASA engineers as influenced by the late 1960s HL-10,[13] and the Soviet Mikoyan-Gurevich MiG-105 military spaceplane concept,[14] a spaceplane studied as a means to develop a Soviet counterpart to the US's X-20 Dyna-Soar.[15]

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.[14]

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.[16]

As of October 2011, Sierra Nevada Corp had completed four of the 13 milestones set out in the CCDev Agreement.[17] The most recent milestones accomplished include: a System Requirements Review, a new cockpit simulator, finalizing the tip fin airfoil design and most recently,[18] a Vehicle Avionics Integration Laboratory (VAIL), which will be used to test Dream Chaser computers and electronics in simulated space mission scenarios.[17]

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."[19]

On 24 April 2012 Sierra Nevada Corporation announced the successful completion of wind tunnel testing of a scale model of the Dream Chaser vehicle.[20]

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.[21] 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.[21]

On 11 July 2012 SNC announced that they successfully completed testing of the nose landing gear for Dream Chaser.[22] 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.[22]

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.[23]

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.[23]

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.[24] 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.[25]

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 12,000 feet (3,700 m) altitude and would be followed by an autonomous robotic landing.[24][26]

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.[27][28]

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.[29]

SpaceDev Dream Chaser proposal

COTS

The Dream Chaser was publicly announced on 20 September 2004[30] as a candidate for NASA's Vision for Space Exploration 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.[31] In April 2007, SpaceDev announced that it had partnered with the United Launch Alliance to pursue the possibility of using the Atlas V booster rocket as the Dream Chaser's launch vehicle.[32] In June 2007, SpaceDev signed a Space Act agreement with NASA.[33]

CCDev

About two weeks after Benson's 10 October 2008 death, SpaceDev agreed to be acquired by Sierra Nevada Corporation, a privately owned company operated by Fatih Ozmen and Eren Ozmen, on 21 October 2008 for $38 million.[34] 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.[35][36] 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.[37] Further initial Dream Chaser tests included the drop test of a 15% scaled version at the NASA Dryden Flight Research Center.[38] The 1.5 m (5 ft) model was dropped from an altitude of 14,000 feet (4,300 m) to test flight stability and collect aerodynamic data for flight control surfaces.[38]

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.[39][40]

On 18 April 2011, NASA awarded nearly $270 million in funding for CCDev 2, including $80 million to Sierra Nevada Corporation for Dream Chaser.[41] 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.[42][43]

CCiCap

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.[44]

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.[45]

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 use 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.[46]

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.[25]

September 2014 CCtCap non-selection by NASA

After being involved with the NASA Commercial Crew Development program since 2009—and being selected as one of the contract award recipients in each prior phase of the program—NASA did not select the Dream Chaser for the next phase of the Commercial Crew Program announced 16 September 2014[47] due to lack of maturity.[48] Sierra Nevada filed a protest to the US Government Accountability Office (GAO) on 26 September. The GAO is investigating and will respond after a process that could take up to 100 days. Boeing and SpaceX were asked by NASA to "stop work" on the crewed spacecraft during the protest resolution.[49] However, on 22 October 2014, a Federal Judge ruled that NASA could proceed with contracts with Boeing and SpaceX to develop their "space taxis", while the GAO continued to consider Sierra Nevada's protest of NASA's original decision.[50]

Two weeks after losing the Commercial Crew Transportation Capability (CCtCap) competition to SpaceX and Boeing on 16 September 2014,[51] Sierra Nevada Corporation announced it has designed a launch system that combines a scale version of the company’s Dream Chaser space plane with the Stratolaunch Systems air launch system.[52] Earlier the same week, Sierra Nevada introduced new spaceflight opportunities to the world - coined the Dream Chaser Global Project"- which would provide customized access to low Earth orbit to global customers.[53]

Despite not being selected to continue forward under NASA’s Commercial Crew transportation Capability (CCtCap) phase of the effort to send crews to orbit via private companies, SNC is still completing milestones under earlier phases of the CCP.[54] On 2 December 2014 SNC announced that it completed NASA’s CCiCap Milestone 5a related to propulsion risk reduction for the Dream Chaser space system.[55]

By late December, details had emerged that "a high-ranking agency official"—"William Gerstenmaier, the agency’s top human exploration official and the one who made the final decision"—"opted to rank Boeing’s proposal higher than a previous panel of agency procurement experts." More specifically, Sierra Nevada asserted in their filings with the GAO that Gerstenmaier may have "overstepped his authority by unilaterally changing the scoring criteria."[56]

On 5 January 2015, the GAO denied Sierra Nevada's CCtCap challenge, stating that NASA made the proper decision when it decided to award Boeing $4.2 billion and SpaceX $2.6 billion to develop their vehicles. Ralph White, the GAO's managing associate counsel, announced that NASA "recognized Boeing’s higher price but also considered Boeing’s proposal to be the strongest of all three proposals in terms of technical approach, management approach and past performance, and to offer the crew transportation system with most utility and highest value to the government." Furthermore, the agency found "several favorable features" in SNC's proposal "but ultimately concluded that SpaceX's lower price made it a better value."[57]

Dream Chaser Global Project

In September 2014, SNC announced that it would, with global partners, use the Dream Chaser as the baseline spacecraft for orbital access for a variety of programs, specializing the craft as needed.[58]

On 5 November 2014 during the Space Traffic Management Conference at Embry–Riddle Aeronautical University, SNC's Space Systems team presented the challenges and opportunities related to landing the Dream Chaser spacecraft at public-use airports.[59] According to the presentation, "Unlike the Space Shuttle, the Dream Chaser does not require any unique landing aids or specialized equipment as it uses all non-toxic propellants and industry standard subsystems."[60]

Stratolaunch and Dream Chaser

In late November 2014, Vulcan Aerospace released the results of the SNC/Stratolaunch space transportation architecture, which indicated that the reduced-size Dream Chaser in conjunction with the Stratolaunch-based launch system mission capabilities. The system would have an outbound range of 1,900 kilometers; 1,200 miles (1,000 nmi) away from the airport where the aircraft departed. The launch vehicle would be a modified air-launched Orbital Sciences rocket that is approximately 37 m (120 ft) in length. The Dream Chaser payload would be a 75-percent sized version of the vehicle previously proposed to NASA—while maintaining the relative outer mold line-6.9 m (22.5 ft) in length with a wingspan of 5.5 m (18.2 ft), which could carry 2 to 3 crewmembers plus a variety of scientific and research payloads.[61]

Dream Chaser for European Utilization

In 2013 SNC and OHB entered into an agreement to study the feasibility of using SNC’s Dream Chaser spacecraft for a variety of missions. The DC4EU study thoroughly reviewed applications for the Dream Chaser including crewed and uncrewed flights to low-Earth orbit (LEO) for missions such as microgravity science, satellite servicing and active debris removal (ADR).

On 3 February 2015, the Sierra Nevada Corporation’s (SNC) Space Systems and OHB System AG (OHB) in Germany announced the completion of the initial Dream Chaser for European Utilization (DC4EU) study.[62]

"The inherent design advantages of the Dream Chaser reusable lifting body spacecraft make it an ideal vehicle for a broad range of space applications," said Dr. Fritz Merkle, member of the Executive Management Board of OHB AG. "We partnered with SNC to study how the design of the Dream Chaser can be used to advance European interests in space. The study results confirm the viability of using the spacecraft for microgravity science and ADR. DC4EU can benefit the entire international space community with its unique capabilities. We look forward to further maturing our design with SNC as we expand our partnership." The cooperation was renewed in April 2015 for additional two years.[63]

Dream Chaser Cargo System

The cargo variant of the SNC Dream Chaser is called the Dream Chaser Cargo System. Featuring an expendable cargo portion, containing solar panels, the cargo version of the spacecraft will be capable of returning 1,750 kg (3,860 lb)[64] to Earth, undergoing re-entry forces of 1.5G. It has been proposed for the Phase II program for cargo resupply of the International Space Station.[65]

January 2016 CRS2 selection by NASA

In December 2014, Sierra Nevada proposed Dream Chaser for CRS-2 consideration.[66] It is in competition with the existing CRS-1 contract holders SpaceX Dragon capsule and Orbital Sciences Cygnus capsule, as well as fellow CCDev competitor Boeing CST-100.[67] In January 2016, NASA announced that Dream Chaser had been awarded one of the contracts under CRS2. NASA committed to purchasing a minimum of six resupply missions to the ISS from Sierra Nevada.[68]

To meet CRS2 guidelines, the cargo Dream Chaser will feature foldable wings, to fit within a 5m cargo fairing, unlike the passenger Dream Chaser, which did not use a cargo fairing. The ability to fit in a cargo fairing allows launches from Ariane 5 as well as Atlas V rocket launcher vehicles. To expand the cargo uplift capacity, an expendable cargo module is affixed aft, which will not support downlift, but can be used for disposal of up to 3,250 kg (7,170 lb) of trash. Total uplift is planned for 5,000 kg (11,000 lb) pressurized, 500 kg (1,100 lb) unpressurized, with downlift of 1,750 kg (3,860 lb) wholly within the spaceplane.[69]

Testing

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.[70]

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.

Wind tunnel testing

In 2014, Sierra Nevada completed its wind tunnel testing as part of its CCiCAP Milestone 8. The Wind tunnel testing involved analyzing the flight dynamics characteristics that the vehicle will experience during orbital ascent and re-entry. Wind tunnel testing was also completed for the Dream Chaser Atlas V integrated launch system. These tests were completed at NASA Ames Research Center at Moffett Field, California, CALSPAN Transonic Wind Tunnel in New York, and at NASA Langley Research Center Unitary Plan Wind Tunnel in Hampton, Virginia.[71]

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.[72] 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.[73] "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."[74] A second captive carry flight test was completed on 22 August 2013.[75]

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

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.[76] 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.[77][78]

On 1 August 2014, the first completed piece of the orbital test vehicle's composite airframe was unveiled at the Lockheed Martin Michoud Assembly Facility in Louisiana.[79]

In October 2015, the thermal protection system was installed on the ETA for the next phase of atmospheric flight testing. The orbital cabin assembly of the FTA orbital test vehicle was also completed by contractor Lockheed Martin.[80]

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,[72] while the FTA was originally named Ascalon before being changed to Ascension.[81]

Dream Chaser model being tested at NASA Langley

In 2014, an initial orbital test flight of the Dream Chaser orbital test vehicle was planned for 1 November 2016, launching on an Atlas V rocket from Kennedy Space Center Launch Complex 41.[25][82] NASA indicated that the first commercial cargo flight by any provider under the CRS-2 contract will not occur until 2019.

Status

In January 2016, NASA announced that Dream Chaser had been awarded one of the contracts under CRS2. NASA committed to purchasing a minimum of six resupply missions to the ISS from Sierra Nevada.[68] The total prices paid under the contract will depend on which mission types are ordered.

Technology partners

The following organizations have been named as technology partners:

See also

Related development

Spacecraft of comparable role, configuration and era

Dream Chaser Cargo System:
Dream Chaser Space System:

References

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  3. 1 2 3 Klingler, Dave (2012-09-06). "50 years to orbit: Dream Chaser's crazy Cold War backstory: The reusable mini-spaceplane is back from the dead—again—and prepping for space". ars Technical (Boston: Conde Nast). p. 3. Archived from the original on 2014-01-06. Retrieved 2012-09-07.
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  59. ↑ "Sierra Nevada Corporation to Present Progress on Evaluating Dream Chaser Landing at Public Use Airports". WFXS FOX55 WAUSAU. 2014-11-05. Retrieved 2014-11-01.
  60. ↑ "Challenges and Opportunities Related to Landing the Dream Chaser® Commercial Reusable Space Vehicle at a Public-Use Airport". ERAU Scholarly Commons. 2014-11-05. Retrieved 2014-11-01.
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  62. ↑ Completion of the initial DC4EU study (2015-03-02). "http://www.sncorp.com/AboutUs/NewsDetails/749"
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  64. ↑ "Sierra Nevada Hopes Dream Chaser Finds "Sweet Spot" of ISS Cargo Competition". SpaceNews. Retrieved 2016-02-20.
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  66. ↑ Christian Davenport (2015-02-13). "Grounded: Left behind in the contracting race to restore Americans to space". The Washington Post.
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  71. ↑ "Dream Chaser passes Wind Tunnel tests for CCiCap Milestone". NASASpaceflight.com. 2014-05-19. Retrieved 2015-01-02.
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  75. ↑ Wall, Mike (2013-08-26). "Dream Chaser space plane dangles from helicopter for second flight test". NBC News (New York). Archived from the original on 2014-01-06. Retrieved 2014-01-06.
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  80. ↑ "Dream Chaser preps for 2nd free-flight test and first orbital test". Space Daily. 2015-10-09.
  81. ↑ "Dream Chaser still fighting for her place in space". www.nasaspaceflight.com. 2015-10-06.
  82. ↑ Dream Chaser's First Launch Will Fly to ISS, SNC Outlines Testing and Development Plans Ahead. Mike Killian, 15 January 2016.

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