For the first time in 42 years, NASA is set to launch a spacecraft designed for humans beyond low-Earth orbit.
The craft, the agency's Orion crew capsule, is a key piece of a space-launch system designed to take astronauts to destinations at lunar distances and farther, eventually depositing explorers on the surface of Mars.
With the demise of the space-shuttle program, Orion is poised to be a cornerstone of NASA's human spaceflight program for decades, setting high stakes for Thursday's unmanned test flight. Its four hours and 24 minutes from launch to splashdown will be monitored by video cameras and some 1,200 sensors designed to measure everything from vibrations and temperatures to the intensity of sounds and radiation inside the capsule.
The moment has a hint of back to the future, given that the basic architecture of Orion and its rocket is an updated version of NASA's Apollo hardware – a crew capsule and service module atop a rocket. But the program also marks an important step in the future of human spaceflight beyond low-Earth orbit as NASA and the Europeans join forces on the project, recognizing that the costs of sending humans deeper into space are likely to be larger than any one country will bear.
If all goes well, an amped-up Delta IV rocket will lift off from the Cape Canaveral Air Force Station in Florida by 8:45 a.m. Eastern time Thursday with Orion perched on top.
The mission aims to test the most risky aspects of the capsule's design:
- Orion's heat shield must protect the craft and crew from the searing heat generates as Orion plunges through Earth's atmosphere on a reentry more fiery than the space shuttles endured. Orion will be reentering at 20,000 miles an hour, with the heat shield expected to reach 4,000 degrees Fahrenheit.
- The craft also must be able to safely shed fairings, or covers, that protect the craft's service module and maintain the rocket's aerodynamic shape during its ascent.
- Orion must be able to jettison its launch-abort system, which consists of an aerodynamic shell that covers the capsule and its topped with a small tower sporting rocket motor to pull the capsule free of the rocket if the rocket malfunctions during its ascent.
- Assuming a normal reentry, the craft's multiple-parachute system needs to prove itself under flight conditions. It slows the craft to a safe splashdown and recovery in the Pacific.
- The craft's computers must withstand or quickly recover from glitches that could be triggered by radiation in space.
"Thursday's a huge day for us," said Mark Geyer, the NASA official who oversees the Orion program at NASA's Johnson Space Center in Houston, during a prelaunch briefing.
"Part of me hopes that everything is perfect: We land, high fives, everybody has a great time. But really, on a flight test like this, if there are subtleties in how the vehicle behaves ... or how systems behave with one another, my hope is that we find that on this test flight. That's what it's all about."
Beyond hardware, Orion marks the beginning of international cooperation in human spaceflight efforts. A year ago, NASA and the European Space Agency inked an agreement for ESA to build Orion's service module, which provides propulsion while on orbit as well as water and oxygen for the crew. The module won't be ready for Thursday's test flight, which will use a rudimentary placeholder. It will fly in 2017, when NASA plans to send an uncrewed Orion capsule to the moon and back. The first crewed mission is slated for 2021 – a figure-8 trip to the moon and back.
"Exploration beyond low-Earth orbit is going to have to be an international activity," said William Gerstenmaier, NASA's associate administrator for human exploration and operations, when the agreement was announced last year.
A National Academy of Science panel echoed that sentiment in June, noting the potential costs of getting to Mars, for example.
"Given the scale of the endeavor of a mission to Mars, contributions by international partners would have to be of unprecedented magnitude to defray a significant portion of the cost," the panel wrote.
For all the talk of new directions in space exploration, though, Orion and its Space Launch Systems rocket are essentially 21st-century versions of 1960s technology.
The physics of returning destinations outside low-Earth orbit dictated Orion's conical shape, as it did for Apollo's command module, or more recently for the heat-shield and aeroshell assembly that protected NASA's Mars Curiosity rover during its "seven minutes of terror" entry into Mars's atmosphere.
Orion is larger than the Apollo command module, capable of carrying four crew members instead of three and sustaining them for missions of up to 21 days. New materials and technology have allowed engineers to keep Orion's weight lower than it might otherwise have been.
One small example: the crew will use flat-panel control screens to operate the craft instead of physical switches. By replacing switches with icon-like "virtual" switches on displays, NASA engineers could get rid of the weight of the switches and the bundles of cables needed to connect them to the systems they controlled.
The craft, however, is still projected to be overweight when it comes time for the first crewed mission, so engineers will be looking for additional places to shave weight from the craft without sacrificing safety or reliability.
For this mission, Orion will orbit Earth twice: the first orbit at an altitude comparable to the space station's, the second will carry Orion some 3,600 miles above Earth before it begins its return for reentry.
At that distance, the craft will have to pass twice through the innermost of two regions of intense radiation known as the Van Allen radiation belts. The passage will provide a key test of how hardy the craft's computer systems are when exposed to space-based radiation. The components on modern computer chips are crammed so tightly that the odds of one getting hit by energetic charged particles are much greater than during the Apollo era.
As if to underscore the Apollo program's influence on Orion and the space launch system, Orion mission planners have sought advice from former Apollo workers, including those involved in capsule-recovery efforts at sea. In addition, Gene Kranz, a former Apollo flight director who oversaw the safe return of Apollo 13, will be among the VIPs at mission control in Houston during Thursday's test flight.
For members of the mission-control team in Houston, the event has a reunion-tour feel to it, acknowledges flight director Mike Sarafin.
"The blended team of Lockheed Martin and NASA personnel that is supporting the mission from within mission control are all shuttle veterans," he said. "It's a good feeling" to have that level of experience and skill on tap for the start of what many hope is a new era of human missions to destinations beyond low-Earth orbit.
[Correction: This article has been updated to correct the launch site. Orion is scheduled to lift off from the Cape Canaveral Air Force Station in Florida.]