As hopes dim of further contact with India's moon rover, the country's space chief has said he was satisfied with the prospect of calling its successful lunar mission to an end.

India began exploring the moon's surface in August after becoming just the fourth nation to land a craft on the celestial body, sparking celebrations in a country rapidly closing in on milestones set by global space powers.

Rover Pragyan—"Wisdom" in Sanskrit—surveyed the vicinity of the moon's south pole but was powered down before the start of lunar night, which lasts roughly two weeks on Earth.

The Indian Space Research Agency had hoped to prolong the mission by reactivating the solar-powered vehicle once daylight returned to the lunar surface, but so far has been greeted by radio silence.

New guidelines are needed to assure that research on human subjects performed on commercial spaceflights is conducted ethically, a panel of experts say in a commentary appearing in the September 28 issue of the journal Science. Their paper is titled "Ethically cleared to launch?"

Private companies are expected to fly thousands of people into space in the coming decades. Those aboard will include workers and passengers who will have the opportunity to participate in research studies. Such research is not only essential to assure the safety of future space travelers but often also addresses critical issues of human health in general.

Buț current ethical rules used to govern research on human subjects do not directly address the unique circumstances of research aboard commercial spaceflights, according to a panel convened by Center for Medical Ethics and Health Policy, Baylor College of Medicine, Houston.

"There has been a long tradition of astronauts from NASA and other national space agencies of volunteering for research, and the agencies have established tradition on how this research is done," said Dr. Michael A.