45th International Conference on Environmental Systems ICES-2015-117 12-16 July 2015, Bellevue, Washington Dream Chaser® Integrated Spacecraft and Pressure Suit Design Kenneth J. Stroud1 Sierra Nevada Corporation, Louisville, CO, 80027 Shane E. Jacobs2 David Clark Company Incorporated, Worcester, MA, 01604 The new era of commercial human spaceflight offers the opportunity to develop new technologies while applying lessons learned from the past. The Dream Chaser spacecraft and the full pressure suit proposed for use by its crew members tie the past to the present in both spacecraft and pressure suit design, in order to maximize crew safety. Sierra Nevada Corporation’s (SNC) Dream Chaser spacecraft is a state-of-the-art reusable lifting-body vehicle that traces its heritage to NASA’s HL-20 lifting body spacecraft design. Due to its design, SNC’s Dream Chaser operates similar to the space shuttle, including the ability for crewmembers to bailout of the spacecraft if an atmospheric contingency is experienced. To protect against rapid cabin depressurization during ascent and entry, as well as the low atmospheric pressure during bailout, each Dream Chaser crewmember will wear a full pressure suit, along with other integrated crew survival equipment. The suit, designed by David Clark Company Incorporated, is a light-weight pressure suit specifically designed for Dream Chaser operations, with heritage in the Contingency Hypobaric Astronaut Protective Suit (CHAPS) and the S1034 pressure suit design that is currently flown by U-2 pilots. As part of maximizing crew safety, several lessons learned from the Space Shuttle Columbia accident and subsequent Columbia Accident Investigation Board (CAIB) report are incorporated into both the Dream Chaser spacecraft and pressure suit designs. These lessons learned include considerations for optimal integration of the suit, seat, survival equipment and cockpit, accommodations for extended visors-down time, and use of a conformal helmet providing significantly improved head protection. In addition, the Dream Chaser spacecraft design requires a vertical climb between the ingress hatch and the cockpit in the launch configuration, which is facilitated by pressure suit design features. Together, the integrated design and development of the Dream Chaser spacecraft and the pressure suit provide next generation human spaceflight capability and safety. Nomenclature AGL = above ground level +Gz = acceleration in the upward direction; “eyeballs down” in-lb = inch pounds MSL = mean sea level ppO2 = partial pressure of oxygen psia = pounds per square inch absolute psid = pounds per square inch differential I. Introduction N July 11, 2011, the Space Shuttle Atlantis landed at Kennedy Space Center, and the United States O relinquished its capability to fly astronauts into space. The U.S. currently has to rely on the Russian Soyuz space capsule to transport NASA astronauts to the International Space Station (ISS), at a cost of over $70 million per seat - more than triple the cost the Russians charged NASA before the end of the Space Shuttle Program in 2006. In order to reduce cost and end U.S. reliance on Russia for transporting American astronauts to space, NASA 1 Crew Systems IPT Lead, Dream Chaser Program, 315 CTC Blvd, Louisville, CO 80027 2 Softgoods Design Manager, Research and Development, 360 Franklin St. Worcester, MA 01604 © 2015 Sierra Nevada Corporation created the Commercial Crew Program (CCP) in 2010 with the goal of transporting crews aboard U.S. spacecraft to the ISS by 2017. At the same time, several corporate and privately-funded space programs have been in development, ranging from air-launched suborbital spacecraft to balloon systems and specialized pressure suits. As part of CCP, Sierra Nevada Corporation (SNC) developed the Dream Chaser spacecraft to transport astronauts and cargo to the ISS. Dream Chaser is a reusable, optionally piloted, lifting body spacecraft that launches vertically on an Atlas V rocket and lands horizontally on a conventional runway. The winged design and vehicle operations of Dream Chaser are reminiscent of the space shuttle, from which several lessons have been learned and applied. To protect against a myriad of hazards, including a cabin depressurization during the mission, Dream Chaser crewmembers will wear full pressure suits, developed by David Clark Company Incorporated (DCCI). DCCI, a pioneer in aerospace crew protective equipment and the designer and manufacturer of the Model S1035 Advanced Crew Escape Suit (ACES)[1] (and precursor Model S1032 Launch Entry Suit and Model S1030A Ejection Escape Suit worn by shuttle crewmembers throughout the Figure 1. Model S1034 Pilots program) has been developing pressure suits for a number of commercial Protective Assembly space applications, including Red Bull Stratos[2]. DCCI has also developed the lightweight Contingency Hypobaric Astronaut Protective Suit (CHAPS) to address the specific and unique requirements of the commercial space market. The Dream Chaser Pressure Suit (DCPS) is based largely on lessons learned from the CHAPS, the ACES, the Red Bull Stratos suits, and the S1034 pressure suit design that is currently flown by U-2 pilots (Figure 1). Unique features from each of these suit systems have been identified and optimized for Dream Chaser applications. The DCPS represents the culmination of design lessons learned from high-altitude full pressure suits with bailout capability. Additionally, a strong focus has been placed on the integrated design of the DCPS with the Dream Chaser spacecraft, such that the suit is an integral component of the vehicle’s many subsystems to which the suit interfaces, including the seats, the life support system, displays and controls, and ingress and egress paths. This paper describes the overall process of developing and integrating the designs of the Dream Chaser spacecraft and pressure suit. To this point, this effort has included the definition of a spacecraft-suit architecture that includes lessons learned from other space flight and aircraft programs, and ingress and egress testing to validate the architecture and provide inputs into the detailed design for both spacecraft and suit. Detailed design has not been completed, and is currently on hold. II. Dream Chaser Operations The diverse crew activities onboard Dream Chaser, from pre-launch to post-flight as well as emergency scenarios, drive the need for a robust system to support the astronauts performing those tasks. Dream Chaser crew operations begin during ingress of the vehicle while it sits in the vertical position on the launch pad, where crewmembers must ingress a hatch on the dorsal side of the vehicle, and climb up into their seats while wearing pressure suits. Astronauts must also be able to exit on their own in an emergency. Dream Chaser ascent operations are automated, with astronauts monitoring vehicle trajectory and systems. Atmospheric entry operations are also Figure 2. Dream Chaser launch automated, with the optional ability for the pilot to manually land the vehicle in case of an anomaly. Similar to the space shuttle, Dream Chaser astronauts also have the ability to bail out of the aft hatch while wearing a parachute to land safety on the ground or into the ocean in an emergency. To protect against a loss of cabin pressure during ascent, astronauts wear pressure suits. © 2015 Sierra Nevada Corporation On orbit operations for Dream Chaser vary greatly depending on the mission. For a mission to transport crew to a space station, Dream Chaser operations would primarily be focused on rendezvous and docking, which would likely occur within one or two days of launch. Other missions could include free flight, where Dream Chaser operations are focused on scientific experiments or other mission tasks (robotics, servicing, observation, etc.) and may include different numbers of crewmembers on orbit for different durations. If a depressurization were to occur during a free flight orbital phase where crew are unsuited, astronauts would don their suits while preparing for deorbit and landing. Before return to Earth, astronauts again don pressure suits to protect against a potential loss of cabin pressure. Although the g-forces during entry in Dream Chaser are minimal (about +1.5 Gz), long-duration crewmembers could lose consciousness during the return to Earth without countermeasures because of their weakened cardiovascular system after living in microgravity for several months. To protect against loss of consciousness during entry, long-duration astronauts must be able to sufficiently recline or be recumbent during entry to ensure that the heart can adequately pump blood to the brain. The time from deorbit burn to landing is approximately 70 minutes, during which the Pilot monitors trajectory and subsystems, able to take over manually during an emergency. Upon nominal landing, astronauts “safe” the vehicle so ground personnel can approach and ingress the vehicle to assist the astronauts out of their seats and the vehicle. In the event of an emergency landing where astronauts must exit the vehicle quickly, they must do so unassisted which requires opening the hatch and jumping down approximately four feet to the ground. Alternatively, they may exit the dorsal hatch on top of the vehicle, and jump to the ground near one of the wing’s leading edges about five feet above the ground. III. Spacecraft and Pressure Suit Integrated Design Due to its similarity to the space shuttle in many respects, including the ability to land on a runway, Dream Chaser is the benefactor of several lessons learned from the Space Shuttle Program. However, Dream Chaser also has some important inherent differences. A. Ingress and Egress While the habitable volume where astronauts live and work is comparable between the two vehicles, the space shuttle crew cabin was short and wide with two decks, and Dream Chaser is long and narrow with a single deck (Figure 3). This makes packaging of hardware, including life support equipment, crew seats and cargo, and crew ingress and egress challenging. With no discernible aisle between crew seats and life support equipment and cargo, the only path between the hatch and the cockpit is over folded seats.