Continual Speedup, Slowdown Could Provide An Artificial Gravity, Eliminating Harm Weightlessness Causes Astronauts

HAMPTON, Va. — Engineers working on the next-generation Constellation Program spaceship system design are considering propulsion units that would slash the current half-year commuting time from Earth to Mars, a senior Lockheed Martin Corp. [LMT] executive said.

This might be accomplished by having the future Ares V heavy-lifter rocket hoist propulsion units or extra propellant into Earth orbit. Then, when the Ares I rocket lifts the Orion space capsule into space, the crew vehicle could have constant acceleration for the first part of its trip to Mars, and then constant deceleration for the remainder of the journey to the red planet.

Kenneth S. Reightler Jr., a vice president with the Lockheed Martin Corp. [LMT] unit Lockheed Martin Space Systems Co. that leads the Orion development program, said this speed-up and slow-down technique would have multiple benefits. He spoke at the NASA Langley Research Center, where he later delivered a lecture on the first half-century of U.S. space efforts.

For example, not only would the acceleration-deceleration technique reduce the time when astronauts are exposed to space radiation, it also would provide a form of artificial gravity, so that astronauts wouldn’t be floating weightless during the long interplanetary trip, he told Space & Missile Defense Report.

Reightler is familiar with the hazards of space travel, having served on two space shuttle missions in the 1990s.

During extended weightlessness, such as International Space Station expeditionary crew members experience over many months, astronauts suffer physical injury.

Aside from the nausea that some experience, they typically over many years lose a sizable percentage of their bone mass, perhaps 15 percent or more. They suffer weakened muscles and loss of muscle as well.

This is on top of the routine stresses of space travel, such as being in a confined space for months at a time, amounting to perhaps half a year on the space station.

A Mars mission would be immensely longer, lasting perhaps two-and-a-half years round trip, Reightler noted. Using conventional propulsion means, coasting most of the way there and back, would mean half a year of weightlessness on the trip to Mars, a year-and-a-half on the Martian surface where gravity is only 38 percent of that on Earth, and then another half-year of weightlessness on the return trip to Earth.

But using a constant acceleration-constant deceleration regime would mean astronauts never would be subject to weightlessness at any time in the more than two-year mission.

The speed-up and slow-down method "does provide an overall increase in the speed of the trip, which reduces your time of exposure" to radiation, Reightler said.

Saving Lives

"And it also does a couple of other things," he said. Having propulsion available throughout the long mission to Mars, instead of just a kick-start rocket thrust near Earth and coasting the rest of the way to the red planet, could save lives, he indicated.

"It does give you, perhaps, the ability to abort" the mission, to turn around and head back to Earth if trouble arises along the way, he said. And that is "something we don’t have today" in the current U.S. space technologies.

While Lockheed is developing the Orion crew exploration vehicle, the space capsule in which four to six astronauts will ride, others are working on the rocket that will take Orion to space. Different segments of the Ares rocket are being developed by The Boeing Co. [BA], Alliant Techsystems Inc. [ATK] and Pratt & Whitney Rocketdyne, a unit of United Technologies Corp. [UTX].

Lockheed also has been involved in many of the robotic orbiters now circling Mars, and rovers working on its surface.

Those systems have beamed back immense amounts of data, and captivating pictures, that have increased human knowledge of the next planet immensely.

For example, they have discovered there indeed is water on Mars, which is critical for any extended human presence there.

In its natural state, that provides astronauts with water for drinking, and for irrigating crops that would be grown on Mars for food.

Further, water — H2O — can be broken up to provide oxygen for breathing, and hydrogen as a fuel for heating homes and offices on Mars, and for powering Martian automobiles and trucks.

Robotic exploration of Mars also has included geological finds, examining whether Mars ever had liquid water flowing on its surface (which data show may have occurred), whether Mars ever had life forms, and where most of the Martian atmosphere disappeared to (questions still unanswered).

Those robots, some of which have operated far longer than expected, have provided a rich trove of knowledge, so that the first astronauts to arrive on Mars will have a huge head start on discovering and exploring the red planet.

Reightler said NASA plans to take some of the technology in those robots and use it in designing and building the manned Mars mission craft.

"What we’re doing robotically on Mars is extremely important in terms of setting the stage for human exploration," he said. "People argue a lot about whether it’s robotic or human" effort that best will unlock the mysteries of Mars, but "I look at it as both," he said. "Both are essential to exploration. The key is figuring out what the right blend is, what the right mix is."

Actually, he noted, even robotic exploration of Mars has immense human participation and involvement, because it is humans who operate the robots, humans who tell the robots what to examine next, humans who receive data the robots transmit on their discoveries, and humans who interpret that mass of information. Thus humans already are involved in exploring Mars, decades before the first human sets foot there.

"A lot of the [robotic] work that we’re doing on Mars will directly contribute to making some fundamental decisions about how humans finally go and explore" Mars, "where they go and how they do it," he said.

Just knowing what resources are there such as water, how difficult it may be to access those resources and what might be done with them, all are critically important and "pretty fundamental to the concept of operations that we’re going to use when people finally arrive," he explained.

And it is unarguable that a human, with creative intellect and comprehension, is capable of actions, comprehension and decision-making that is far beyond that of the most advanced robot.

"There is something special about the human spirit, the human presence, that robots can’t provide," he said. For example, he said, a robot could be programmed to create a painting, a work in oil, but it wouldn’t be something that a collector of fine art would hang in a home or gallery.

Still, the manned Mars mission is decades distant, and the American public may not be galvanized by the prospect, as it was in the 1960s when President Kennedy made the decision to go to the moon.

That is a key issue, Reightler said: how can one fire the public imagination, to generate the excitement that a great endeavor requires? "How do you get people excited about what we’re doing today?" he asked.

Clearly, the public has become inured to the reality of space travel, and "it’s not quite as shiny and new" as it was decades earlier, he said. "In some ways, NASA is the victim of its own success, and its own … capabilities and efficiencies that made it look pretty easy."

That isn’t the case, for there never is a simple, safe space mission, but the appearance that it is a commonplace may make people "lose interest and focus on other things," Reightler said.

The positive point, however, is that when Reightler speaks to groups about the space program, it never bores them. Rather, they are "pretty supportive, pretty interested," he said.