Sierra Nevada Corporation’s Dream Chaser may become America’s new spaceplane to make it to orbit. The third transportation vehicle for NASA’s Commercial Resupply Services 2 contracts for resupply efforts of the International Space Station (ISS) has passed a major test milestone last week. The Dream Chaser spaceplane conducted the first of a series of captive-carry tests at Edwards Air Force Base, California, marking the second time the Dream Chaser has been present for testing at the desert facility. It was a far cry from the last time the spacecraft had taken to the skies there four years earlier.

Dream Chaser’s setbacks, milestones and upcoming tests

After its initial reveal earlier this decade, Dream Chaser’s long-term prospects were relatively grim. On October 26, 2013, Dream Chaser had attempted an automated approach-and-landing test over Edwards Air Force Base. The test saw Dream Chaser hoisted to altitude underneath a helicopter before being released for an autonomous flight to the runway. The test was designed to simulate the last few minutes of a return from orbit. However, as the spaceplane approached the runway, the unmanned spacecraft’s left landing gear failed to deploy and the plane was damaged as it skidded off into the desert.

The setback dealt a serious blow to the Sierra Nevada Corp., which was in the third round of competition with Boeing and SpaceX to obtain a contract for NASA’s 2014 Commercial Crew Program to carry U.S. astronauts to the ISS. Dream Chaser was eliminated from the program, as the contracts were awarded to Boeing and SpaceX worth $4.2 billion and $2.6 billion, accordingly. The first crew flights are scheduled for 2019, Space.com reports.

Sierra Nevada appealed the decision with the U.S. Government Accountability Office, but lost. Despite the setback, the company pushed forward with development of Dream Chaser on its own. It secured an unfunded Space Act Agreement (SSA) with NASA to continue cooperative development of Dream Chaser. This SSA worked significantly to Sierra Nevada’s favor as NASA awarded the company a contract to deliver cargo to the ISS, along with SpaceX and Orbital ATK, as part of the second round of Commercial Resupply Services (CRS2) contracts awarded to commercial companies by the agency.

According to NASAspaceflight.com, Sierra Nevada is proceeding with a final testing sequence of Dream Chaser, capitalizing on previously conducted tests of the Engineering Test Article (ETA) of the spacecraft. The recent captive-carry test – in which the spacecraft was suspended under a Columbia 234-UT lifting commercial helicopter by a 200 foot (61 meters) long cable for the entire flight – was a success. As the 30 foot (9 meters) long spacecraft descended to 200 feet (60 meters) over Rogers Dry Lake bed in California, its landing gear deployed and locked into position exactly as planned.

“We are very pleased with results from the captive-carry test, and everything we have seen points to a successful test with useful data for the next round of testing,” said Lee “Bru” Archambault, Sierra Nevada Corp. director of flight operations for the Dream Chaser program.

U.S. Air Force photo by Kenji Thuloweit

The flight allowed engineers to test an updated set of electronics used by the spacecraft that are specifically designed for orbital flights, said Steve Lindsey, Sierra Nevada vice president of Space Exploration Systems, Space.com reports.

The avionics used in the recent test were different from the ones used on the approach-and-landing and three captive-carry tests conducted four year ago. “All the avionics worked exactly as expected”, Lindsey told reporters. “We obviously have to look at the data. We have reams and reams of data we’ve got to go look at. But [based on] what we saw [in] real time, everything was working exactly as expected.”

If the data look good, Sierra Nevada will conduct a second captive-carry test from NASA’s Armstrong Flight Research Center around the end of September. With one approach-and-landing test already completed, impaired only by a landing-gear failure, engineers are hoping to complete the glide phase of testing with just one more free flight. This test, it is planned, would follow later in the fall.

“We will fly when we’re ready. We will not fly before that time, no matter what,” Lindsey said. “So, we make sure the team is not under schedule pressure. We obviously are motivated to get this done as soon as we can. On the other hand, we’re not going to do it until everything’s right.”

The approach-and-landing test is a funded milestone under the Commercial Crew Integrated Capability (CCiCap) contract that Sierra Nevada signed with NASA. Although the company lost the commercial crew contract to Boeing and SpaceX, it will still receive $8 million from the space agency once the flight tests are completed.

The CCiCap contract has been extended through 2022, and Sierra Nevada is continuing to work with NASA to qualifying Dream Chaser for astronaut spaceflight. The agreement lists a series of eight milestones and is currently unfunded, meaning that the space agency is not paying the company for further work.

Sierra Nevada’s space station cargo resupply contract with NASA stipulates a minimum of six Dream Chaser flights between 2019 and 2024. Although the agency has not formally ordered any flights yet, company officials said they are expecting Dream Chaser to fly its first mission to the station in 2020, according to Space.com.

Moreover, Dream Chaser has been selected by the United Nations to fly un-crewed microgravity science missions for nations that do not have domestic access to space, the first of which is expected no earlier than 2021. The Trump Administration is understood to be studying a proposal set forth by Sierra Nevada to use Dream Chaser for a crewed servicing mission to the Hubble Space Telescope in the 2020s, NASAspaceflight.com reports.

How the Dream Chaser space plane works

Sierra Nevada has been developing the Dream Chaser spacecraft to carry astronauts to Earth’s orbit and to the ISS for more than 10 years. It leverages more than 40 years of X-vehicle and NASA space shuttle heritage. According to the corporation, there are currently two Dream Chaser variants optimized specifically for either un-crewed or crewed missions, known as the Dream Chaser Cargo System and Dream Chaser Space System. Additional variants may be developed for future mission needs, the company claims.

The Dream Chaser is a planned reusable winged spaceship designed to launch atop an Atlas 5 rocket to carry astronauts and cargo into low-Earth orbit. The spacecraft would carry crews of six or seven people and is based on the HL-20 lifting body design developed by NASA after Russian engineers developed Russia’s BOR-2 craft during the 1980s and 1990s.

Photo by Ken Ulbrich

The Dream Chaser cargo vehicle consists of two elements. The main vehicle is a lifting-body spacecraft capable of re-entering the Earth’s atmosphere and gliding to a landing on a runway in the same way the space shuttle did. This portion of the spacecraft would carry pressurized cargo back to Earth. The other element is a disposable payload module for unpressurized cargo that will separate from the main vehicle before re-entry and burn up in the atmosphere.

The Dream Chaser will be able to deliver up to 5,500 kg (12,125 lbs.) of pressurized and unpressurized cargo to the orbiting laboratory. The spacecraft will be capable of returning up to 1,750 kg (3,850 lbs.) of cargo to Earth. The expendable cargo module will be able to dispose of up to 3,250 kg (7,165 lbs.) of trash from the space station.

During return trips to Earth, the Dream Chaser will expose sensitive scientific payloads to a maximum of only 1.5 times the force of gravity (1.5 g’s). This is far less than the 4 to 8 g’s that astronauts experience when they make a ballistic return to Earth on Russia’s Soyuz spacecraft, which lands under a parachute. SpaceX’s Dragon and Boeing’s CST-100 Starliner are also ballistic spacecraft that will land by parachute.

For its first two CRS2 flights, the Dream Chaser spacecraft will be launched aboard a United Launch Alliance (ULA) Atlas 5 rocket from Cape Canaveral, Florida. Upon returning from space, the Dream Chaser vehicles will glide to landings at the former Shuttle Landing Facility at NASA’s Kennedy Space Center.

In addition, the spacecraft’s runway landings will also give scientists rapid access to experiments and samples that are returning from the station, unlike with some cargo vehicles that fall into the ocean, or the Soyuz spacecraft, which lands in a remote part of Kazakhstan. Sierra Nevada has been working with Ellington Airport in Houston and Huntsville International Airport in Alabama to ensure alternative landing sites for scientists in those locations who fly experiments to the station. Landings there would also expose the public to the Dream Chaser.

Sierra Nevada proposes that the advantages of Dream Chaser extend well beyond ISS resupply. The spacecraft would afford opportunities for continued advanced developments in the areas of servicing for future space stations; satellite servicing/deployment and retrieval; orbital debris removal and serving as a test for exploration technologies. The company says it has begun discussions with multiple international agencies regarding the use of Dream Chaser on a global scale, designing it to be a solution for a wide range of missions and clients, bringing global access to space closer.

Lindsey said the company plans to put the Dream Chaser it is now testing in California in “flyable storage” after the approach-and-landing test is completed. That will save the option of upgrading the vehicle for human spaceflight in the future. “The structure was rated for people from the very beginning, and so we want to keep that as an option… Our intent, someday, is to go back to crew as well,” he said, although how and when is not yet known, Space.com reports.