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. Last Updated: 07/27/2016

NASA Seeks Sign From Mars Lander

PASADENA, California -- NASA sounded increasingly gloomy Sunday about the chances of ever contacting the $165 million Mars Polar Lander, after scientists again listened in vain for a signal during two chances to communicate with the spacecraft.

Mission officials tried using a different antenna during the first opportunity to detect a signal Sunday morning. However, the effort failed, and there have been no communications with the lander since its touchdown Friday.

Mission controllers admitted late Sunday it is growing more likely that contact may never be made.

"Clearly the team is getting more frustrated, certainly, and more tense about all of this," operations manager Richard Cook said.

The spacecraft was supposed to have signaled immediately after landing about 800 kilometers from the Martian south pole.

Instead, several windows of opportunity came and went over the weekend with no sign of life from the unmanned craft. The ever-more ominous silence raised the prospect that the lander was destroyed or severely damaged during its descent to the planet's surface.

"We're disappointed we didn't get communications tonight, but we're going to attempt with some confidence through tomorrow," Cook said Sunday. "And the team is working on other possibilities beyond that, but the probability of success will diminish significantly after tomorrow night."

If no signals are heard, it would be total loss for the entire $330 million Mars 98 project, which consisted of Polar Lander, the Deep Space 2 microprobes and the Climate Orbiter, which burned up over the Red Planet in September.

Two tiny probes that rode aboard Mars Polar Lander but separated before entry appear to be lost forever. The softball-sized microprobes were supposed to slam into the surface at 644 kilometers per hour to test a new descent technique that did not use expensive parachutes or rockets to break the fall from space. If the test flight had been successful, future microprobe missions could be sent to cover a wider territory at less cost than current spacecraft.

The $29.6 million probes were to have emitted their first signals on arrival Friday, like Polar Lander. Every two hours, the orbiting Mars Global Surveyor tried to detect any transmissions from the microprobes to no success.The probes also had been programmed to transmit automatically once every five minutes if they did not receive commands from Global Surveyor after 29 and 32 hours. No signals were picked up during those opportunities as well.

"If we haven't heard from them in the next 24 hours, we will have exhausted our opportunities to hear from them," said Sarah Gavit, the probes' project manager.

Meanwhile, the Polar Lander controllers attempted to find a signal for the third straight day Sunday. Several windows of opportunity came and went over the weekend with no sign of life from the unmanned craft.

Lack of any signals since shortly before Friday's scheduled landing left mission officials with hope only that the lander survived the touchdown and, on its own, was taking steps to establish contact.

Mission managers worked on eliminating simple failure scenarios one by one. But they conceded that if, after trying all the obvious remedies, contact still has not been established by midweek, the explanations for the failure would become more complex and the prospects of success would greatly diminish.

"When you start stacking - if this thing has to fail and then this thing has to fail and then this thing has to fail to get into this circumstance - then you're definitely in extra time," Cook said. "We're not there yet. I think we will be, come Tuesday morning."