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D-RATS Set Sights on Asteroid
09.30.11
 
The D-RATS operations base in Arizona.The Desert Reseach and Technology Studies group set up a compound in the Arizona desert as they worked for two weeks simulating a mission to an asteroid. Note the two Space Exploration Vehicles and the Deep Space Habitat. Photo credit: NASA
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Astronaut Kjell Lindgren performs a simulated spacewalk during the 2011 Desert RATS mission. Photo credit: NASA/Regan Geeseman.Astronaut Kjell Lindgren checks the wrist display of his Advanced Extravehicular Activity Information System during a simulated spacewalk during the 2011 Desert RATS mission. Photo credit: NASA/Regan Geeseman.
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Artist concept of spacecraft exploring asteroid.This artist concept shows a method to explore an asteroid. The main elements in the concept were accounted for in the D-RATS exercise. Artist concept credit: NASA
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As far as challenges are concerned, going to an asteroid comes with all the standards for a space destination such as no air, lags in communication with Earth and the radiation risks that come with being in space.

Compared with going to the moon or Mars, though, asteroids demand explorers consider another significant factor: there's virtually no gravity. The astronauts that bounded enthusiastically on the moon might have bounced themselves right off into space if they had been on an asteroid instead.

Finding the best combination of equipment and number of astronauts to deal with communications challenges while surveying an asteroid was one of the goals of this year's trip to Arizona for research known by its acronym, D-RATS, short for Desert Research and Technology Studies.

"Each day we went out with a different architecture," said Marc Seibert, who leads a variety of communications and navigation systems projects for Kennedy's D-RATS contingent. The designs are intended to operate in any space environment.

The explorers used backpacks developed at Kennedy equipped with cameras and space versions of the tools of the modern communications world. The backpacks were developed as a mobile office for the explorer. They made their first field tests during last year's D-RATS.

Previous years have seen the desert stand in as the moon or Martian surface, but this year's effort was the first to prep for an asteroid.

"We're trying to build this as a framework to go to multiple destinations," said Tracy Gill, an engineer at NASA's Kennedy Space Center who works on the D-RATS projects.

Several NASA centers take part in the exercise providing specific programs and tools. Astronauts make the desert excursions which basically experiment in different scenarios to find out, for example, how many people should go on a mission to an asteroid, how many are needed to explore on the surface and what are the best ways to actually conduct the research.

From trying out a Robonaut assistant to placing handrails on the asteroid's surface, researchers set out to formulate the best methods, tools and needs for the work.

To simulate the communications environment, the network was programmed with a 50-second delay in communication between the astronauts and the actual mission control in Houston. With the time delay on a representative asteroid mission, voice communication between Earth and an exploration team could be complicated during critical operations, so "We have a text messaging tool so it's not blaring in their ears," Gill said.

The delay is critical to show researchers when automated processes should be developed and to train astronauts what to expect when they are waiting for guidance from Earth for certain steps or unexpected circumstances.

The researchers brought with them mockups of a rover and living quarters very much like the ones that would be taken into space. A Robonaut mounted on a rover chassis came along too.

"This whole architecture would go to the destination," Gill said.

The rover, called the Space Exploration Vehicle or SEV, is being designed with numerous settings in mind, Seibert said, so considering it in an asteroid environment was useful for fine-tuning its design.

For example, a rover would need wheels on the moon, but those might be useless on an asteroid, where a small bump at high speed would send the rover off the surface and into space. So, maybe a set of automated thrusters or a cable and anchor that allow station-keeping would be more valuable, for instance.

Seibert said the group proved that steering the vehicle and conducting science at the same time requires two people in the vehicle rather than counting on one person to do both.

Additionally, this year’s Desert RATS saw the first prototype version of a Deep Space Habitat (DSH), which can be configured for microgravity of surface exploration missions. The Deep Space Habitat contains work stations to support the astronaut’s science and maintenance activities on an exploration mission and habitation systems for long-term space flight. The DSH has significant contributions from Kennedy ranging from systems such as a deployable work platform to technology demonstrations, such as dust mitigation and damage detection systems.

NASA recently made asteroid studies a priority. The Dawn mission to two of the largest asteroids in the solar system, Vesta and Ceres, is one example. A future mission called Osiris-Rex is to bring back pieces of an asteroid in 2016. The NEAR spacecraft, short for Near earth Asteroid Rendezvous, landed on the asteroid Eros in 2001 as it orbited 196 million miles from Earth, more than seven times farther away than the moon.

The D-RATS scientists typically publish about two dozen scientific papers detailing their findings after each mission.

The next steps in the evolution are not destined for the desert, but rather the sea floor. To work in an environment replicating the lack of gravity better, researchers plan to use NASA's Extreme Environment Mission Operations base in the Florida Keys known as NEEMO to work with the space exploration vehicle. In the ocean, the SEV mockup will be able to float near the ocean floor and work near an astronaut outside the vehicle in much the way it would around an asteroid.

Next year, the D-RATS are to become Lab RATS instead, Seibert said, working with a specialized air-floor at NASA's Johnson Space Center in Houston to simulate the gravity field.

Seibert said, "It's an evolutionary process, for sure."