Astronauts on the International Space Station this summer will use instant messaging, Internet chat clients and email to contact mission control, the first in a series of experiments designed to exploit the orbiting outpost as a behavioral laboratory for future journeys to an asteroid or Mars.

File photo of the International Space Station. Credit: NASA
 
The exercise will lead to a voice communications delay, expanded autonomy for the space station crew, and, eventually, the extension of orbital crew flights from six months to one year or longer.

"Clearly, in order to be able to explore beyond low Earth orbit, we're going to have to stay in orbit longer than six months," said Michael Suffredini, NASA's International Space Station program manager.

Russia has proposed a 500-day expedition, replicating the estimated round-trip travel time between Earth and Mars. Vladimir Popovkin, head of the Russian space agency, told the Novosti news agency he expects a 500-day mission could be mounted on the space station by 2017 or 2018.

Before launching a crew to fly up to 500 days - more than 16 months - managers may decide to schedule space station expeditions lasting nine months or a year. But it could be several years before NASA managers are comfortable with even a modest mission extension for space fliers.

"It's not reasonable to think we would be able to do this sooner than two or three years from now," Suffredini said.

Agency heads from the space station's five international partners discussed longer mission durations during a March 1 meeting in Canada, according to Suffredini.

"That's not an activity that's going to occur tomorrow," Suffredini said. "We're taking steps and we will evolve to this point over a number of years, so we can get all the data we need over the ISS lifetime."

A night view of the U.S. East Coast from the International Space Station. Credit: NASA
 
The space station program will continue until at least 2020.

"I suspect that the consensus of opinion is that we will want to simulate in low Earth orbit at least the first leg of a trip to a distant planet," Suffredini said.

Missions now are limited to about 200 days, the certified life span of Russia's Soyuz capsule, the lifeboat for space station crews. Officials prefer to keep expedition lengths less than 180 days, or approximately six months.

Despite growing experience in spaceflight, medical doctors still want to address several key questions about the effects of long-duration space travel on the human body.

"There are challenges to the physiological system that we're not ready for if we were to plan for Mars, for example, tomorrow," said Tara Ruttley, NASA's associate program scientist for the space station.

Astronauts lose between 1 and 2 percent of their bone mass every month in weightlessness, raising questions on how crews could function in the gravity of another planet after prolonged microgravity. The withering of bone mass can lead to higher levels of calcium in urine, causing an increased incidence of kidney stones in astronauts.

Good nutrition, exercise and medicine can combat bone density issues, according to doctors. But there are few data points on how astronauts' bodies respond to missions longer than six months.

Ten space fliers have been on missions lasting more than 200 days. Russian cosmonaut Valeri Polyakov did it twice, including a record flight of nearly 438 days on the Mir space station in 1994 and 1995, the longest space mission ever.

The crew of space shuttle Discovery snapped this photo of Russian cosmonaut Valeri Polyakov aboard the Mir space station in February 1995, near the end of the Polyakov's nearly 438-day mission. Credit: NASA
 
"A lot of the research we're doing is on what happens to the human body," said astronaut Sunita Williams, who will launch to the space station in July. "There are a lot of unknowns out there - bone density, radiation. We've got our foot in the door, with a number of expeditions under our belt, about understanding some of that research, but there's still a lot more research that has to go on to understand exactly what's happening to the human body and how can we optimize physical fitness, shielding for the radiation, or nutrition to have people stay in orbit for a long time."

The International Space Station has been permanently staffed since November 2000.

Muscles also atrophy in space, but workout regimens can minimize, and even reverse, that trend.

The immune system is weakened by microgravity, the heart and lungs become less efficient, and many astronauts experience worsened visual acuity, with some eyesight loss unresolved years after flying in space.

Astronauts embarking on deep space voyages will be exposed to high radiation doses. NASA's Mars Science Laboratory mission on the way to the red planet is measuring radiation levels throughout its eight-month transit.

Researchers want to observe not only astronauts' biological reactions to spaceflight, but their mental, emotional and behavioral responses to long-term confinement and great distances.

Another objective is to test how crews in deep space will interact with controllers on Earth.

Radio signals travel at the speed of light, and it can take more than 20 minutes for data, voice messages and other communications to travel to Mars and back. Operators of robotic scientific probes to distant planets are familiar with the data delay, but no human space mission has ever dealt with the challenge.

Dina Contella, lead flight director for the space station's Expedition 32 mission, which begins in July, said astronauts will use email and instant messaging to communicate with mission control in Houston. Engineers will send up autonomous procedures to the astronauts, placing controllers on the ground out of the loop.

Station residents now are able to call the ground at almost any time to ask questions, clarify requests and speak with physicians, family and friends.

Williams, who will take command of the space station in September, will launch July 15 with veteran Russian cosmonaut Yuri Malenchenko and Japanese astronaut Akihiko Hoshide. NASA astronaut Joseph Acaba, who is scheduled to fly from May until September, may also be aboard the complex when the communications experiment begins.

Russian cosmonaut Yuri Malenchenko, NASA astronaut Sunita Williams, and Japanese flight engineer Akihiko Hoshide will live on the International Space Station from July until November. Credit: NASA
 
The plan calls for Williams, Hoshide and Acaba to each dedicate a half-day per month where they will not talk to mission control. Their interaction will be limited to email, online chats and file transfers, according to information provided to Spaceflight Now.

Flight controllers will "send up to the crew more autonomous procedures, procedures that involve the ground a little bit less," Contella said.

More autonomous operations are planned later this year, setting the stage for a delay in voice communications beginning as soon as March 2013, according to NASA.

"We'll assess a voice delay of up to 10 minutes, so the round-trip delay would be up to 20 minutes," a NASA statement said. "We expect the voice delay to help us study how the long duration space missions may affect the way flight and ground teams work together. We also believe it will help us identify any risks that delayed communications may cause to our flight and ground teams."

Suffredini said engineers will retain the ability to override the simulated communications interval in case of an emergency.

Later communications delay experiments will add a ground commanding delay to the voice lag, according to NASA officials. Spacewalks, major repairs and research on the space station may ultimately incorporate communication delays.

"We will also evolve these communications delays to simulate a Mars transit mission where the delay starts small and progresses until it matches the delay that would be encountered with a full Mars transit mission," the statement said.

According to Contella, text, photo and video messages will work better than conventional two-way voice links when crews in space and on the ground must wait minutes to hear a response.

"You can imagine if we had a [ground controller] calling up to the crew and there was a significant delay - this would be in some future mission - you would wonder, 'Did they hear me? I have something else I want to add,'" Contella said.