Mars Craft Still Not Responding

Despite its most ingenious efforts, NASA once again failed to rouse the Mars Polar Lander Sunday, making it more likely that an entire flotilla of U.S. Mars explorers--a $356.8-million project involving two major spacecraft and two auxiliary probes--has been lost at the Red Planet this fall.

On Sunday, it took just six minutes of silence between the planets to tip faint hopes at the Jet Propulsion Laboratory into disappointment as the first of several communication efforts failed to produce a signal from the missing $165-million lander or its two small Deep Space 2 probes.

The three craft have not been heard from since they began their descent to the Martian south pole Friday. A sister spacecraft, the $125-million Mars Climate Orbiter, disappeared Sept. 23 as it began to orbit the fourth planet.

“Clearly the team is getting more frustrated, certainly, and more tense about all of this,” said Polar Lander project manager Richard Cook. “Our confidence is less and less that we landed successfully.”

As prospects grew grimmer, questions began to surface about the technical, scientific and political consequences of the mishap and its long-term impact on interplanetary exploration. NASA has a succession of spacecraft scheduled to rendezvous with Mars over the next several years.

Throughout the day, JPL engineers worked gamely on an increasingly complex and ever-more unlikely list of options to gain contact with the craft.

With no information from the spacecraft since it prepared to enter the Martian atmosphere, mission officials cannot be sure the Polar Lander actually reached its destination. But they have been working under the assumption that the craft survived its landing and was making its own automated efforts to radio Earth.

During Sunday’s first failed communications attempt, flight operations engineers tried to contact the lander through a secondary UHF antenna aboard the craft. Late Sunday evening, the engineers tried again by commanding the craft’s primary antenna to search for Earth in a predetermined sweep of the Martian sky.

For 90 minutes, the engineers watched vainly for any signal from the surface of Mars, staring at their computer consoles as intently as surgeons monitoring life support systems in an intensive care unit.

They intend to test several other scenarios during attempts today and Tuesday to contact the spacecraft.

Although flight operations engineers still had several “big cards” yet to play, Cook acknowledged that should those fail to evoke a response from the lander in the next 48 hours, the JPL team will “have reached the point of diminishing returns.”

Beyond that, there will be still other technical options to explore, he said, but “frankly, the likelihood of success with these is pretty small.” Even so, he added, “The mission can be recovered if any one of them turn out to be a success. These are all recoverable problems.”

In the meantime, engineers for the $29.2-million Deep Space 2 microprobes jettisoned by the lander on its descent tried every two hours Sunday to communicate with the two microprobes through the orbiting Mars Global Surveyor.

“The probes may have arrived in an area of high slopes, rough terrain or sand dunes,” which might block their antenna, said Deep Space 2 project manager Sarah Gavit. The batteries that power the probes--barely strong enough to light a Christmas tree bulb--also could have frozen in the subzero Martian spring, she said.

The missing spacecraft were all part of a new wave of relatively inexpensive robotic missions to Mars, designed to learn more about the planet as a prelude to human exploration of Mars sometime in the next century.

In the spring of 2001, for example, three more Mars spacecraft are scheduled for launch, including an orbiter similar to the one that vanished in September and a lander like the missing craft now being sought at the Martian south pole.

Even before NASA has officially declared the lander a dead loss, JPL mission managers were formulating second thoughts and design changes that might be applied to these and other Mars missions in development.

Carl Pilcher, NASA’s science director for solar system exploration, said, however, that it was too soon for the space agency to know how future missions might be affected by the loss of the lander and the scientific data about Martian climate and geology it was designed to gather.