"Rehearsal for the Moon," Feature Article, December 2007

rehearsal for the moon

The contractor says it's a new relationship with NASA; a physical and a digital mockup work together to refine the design of the next idea in space travel.

This article was prepared by staff writers in collaboration with outside contributors.

Orion has sparked the human imagination for a long time. There's a theory that, before it entered Greek mythology, the name originated in Mesopotamia millennia ago, as Uru-anna, usually translated as "Light of Heaven." Another theory suggests that the pyramids at Giza were arranged to represent individual stars in the constellation.

Now, in our age of science and technology, the name is being applied to a new project that represents just as deeply our fascination with the heavens.

The crew vehicle for the next generation of space travel has been dubbed Orion. The vehicle, which will replace the aging Space Shuttle, is expected to carry people back to the moon and perhaps on to Mars.

A rendering of the Orion crew vehicle.

According to NASA, Orion will be similar in shape to the Apollo spacecraft, but significantly larger. It will be able to carry a crew of six to the International Space Station or four astronauts to the moon. Orion is scheduled to reach the space station by 2014 and the moon by 2020.

The contractor for Orion, Lockheed Martin Corp., is currently working with NASA on human-factors simulations to develop the command module for Orion. Working directly with astronauts, the two organizations are building a computerized mockup of the Orion crew exploration vehicle in Denver and a physical mockup at NASA's Johnson Space Center in Houston.

The mockup will be a key tool in training Orion astronauts and, according to Lockheed Martin, the process of developing it may serve as a new model for government-industry collaboration.

saving with simulation

The Orion digital model is intended to speed the development of the physical mockup and is reducing Orion development costs by working out modifications and refinements in simulations rather than with carpentry.

The virtual Orion simulation is being built by Chris Delnero, a senior mechanical engineer at Lockheed Martin Space Systems Co. in the Denver suburb of Littleton. His task is to come up with a technical basis for crew arrangement, crew spacing, and seat design. It's his job to ensure that crew members can reach the control consoles. Using human task modeling software from Auburn Hills, Mich.-based Delmia Inc., he has created a variety of virtual astronauts for simulations that will analyze the human factors of inhabiting the Orion environment.

Delnero's finished simulations are presented to the design stakeholders in design reviews and technical interchange meetings on environmental management, navigation, piloting, and communications. The simulations foster discussions among Lockheed Martin and NASA engineers and the astronauts. The exchange of ideas reduces the need for repeated modifications and iterations of the physical mockup in Houston.

The Orion challenges are enormous, hence the need for intensive simulation. Almost half the space inside Orion—approximately 700 cubic feet—will be packed tight with crew gear, avionics, computers, life-support systems, and heat protection.

If a component or system is to be added, something else must be set aside. The effects on the crew and the mission must be considered in exhaustive detail.

getting a good fit

The digital work consists of modeling the command module and simulating the astronauts and their tasks, including interactions with the controls of the vehicle and access to modules that require in-flight maintenance, such as life support. Hence the initial human-factors focus on touch, feel, shapes, and spaces.

Fit is very important. Orion must be engineered so astronauts will have clearances for feet, knees, and elbows, and will avoid head bumps. NASA requires that Orion accommodate every human height from a first percentile woman—smaller than 99 percent of all women—to a 99th percentile man; i.e., taller than 99 percent of all men. They are represented in the model as manikins.

Delnero has designed the manikins to represent astronauts wearing bulky space suits and helmets, as required for some missions, to see how they fit the planned interior of the vehicle. Dynamic simulations, using animated manikins for the pilot and mission commander, are planned for later phases and will study how people will be able to move and work in the space.

The digital mockup totals just over 200 megabytes, and could grow as much as tenfold when dynamic analyses begin. The model runs on a Hewlett-Packard Co. HP 4100 workstation with 3 gigabits of random access memory. Its Intel Corp. Xeon CPU has a 2.8 gigahertz clock speed.

"Manikins of any size can be created and the analyses done in a matter of minutes," Delnero said. The biggest time factor in simulation is importing solid models. NASA provides models from Pro/Engineer Wildfire 2.0, which must be prepared using Delmia's STEP Core software.

Most of those files are hundreds of megabytes in size and some approach a gigabyte. Almost every file contains thousands of digital objects.

Dealing with each STEP file takes about two hours, including creating surfaces and color. Objects and surfaces unneeded in human-factors studies, such as the structure of the pressure vessel, are hidden or deleted.

seeing the entire picture

According to Delnero, the simulations are giving engineers and even some managers their first clear look at the relative dimensions and scales of everything inside Orion and the very small volume they have to work with. It is also providing greater understanding of the astronauts' tasks by representing the whole interior of Orion, and not just a small part of it with one astronaut doing a specific task.

The modeling has also laid to rest some uneasiness about getting the crew in and out by simulating a tall crew member using the hatch.

After delivering his first control layout modifications for the physical mockup, Delnero was able to climb into the pilot's seat of the physical mockup at the Johnson Space Center. "What the software said I could reach, I could reach," he said. "What it said I would not be able to reach, I could not."

The final piece of the outer shell of a mockup of NASA's new spacecraft concept is put in place at the Johnson Space Center.

The left-eye and right-eye fields of view in the simulations also proved out. "What I could see with one eye versus with the other in the Houston mockup was just what the simulations indicated," Delnero said.

NASA tested the physical mockup in Houston by asking 10 astronauts to perform a virtual docking with the space station. The placements and sizes of viewing ports had been determined by Delnero's simulations.

The fidelity of the Orion computer model is very important for building the physical Orion prototype at Houston, the engineering managers said. In turn, that model is a key part of the big picture of engineering the spacecraft. Simulations allow quick iterative studies, in which a series of small changes in a model are evaluated one at a time.

In its Orion program, Lockheed Martin Space Systems management is determined to build a cooperative and mutually supportive environment with NASA—and avoid the adversarial relationships of some past programs.

According to engineering managers, simulation is especially valuable where Lockheed Martin is now—in early-stage discussions, when design requirements are still in a state of flux.

"The simulations help show, to everyone's understanding and satisfaction, that they represent the real world," one manager said. "The simulations most certainly are not cartoons," the manager added. "They are built with current engineering data, and our analyses reflect a good level of engineering sanity."

According to a Lockheed Martin spokeswoman, Joan Underwood, "This is a highly innovative way of doing business that is based solidly on what we actually know, what will work and what will not, given the dimensional constraints." Working with NASA, she said, "is all about working within, and then leveraging, their processes."