Since its batteries ran out just days after a bumpy landing on the comet named 67P/Churyumov-Gerasimenko (C-G) in November last year, Philae has been silent and its exact location remains a mystery, scientific journal Nature reported.
But Rosetta has only limited fuel and any attempt to look for Philae would mean scrapping another flyby, sacrificing a chance to image the comet in a shadow-free shot that should reveal unprecedented detail.
After the coming flyby, planned for Valentine's Day next month, Rosetta will not come this close again until 2016, once the comet has swung around the Sun and headed back out to space.
"If we are going to change plans to target looking for the lander, that impacts some of the goals we had planned," said Joel Parker, research astronomer at the Southwest Research Institute in Boulder, Colorado.
The debate involves weighing the science goals of both options, as well as the chances of finding Philae, he added.
A process of deduction has put Philae's location somewhere within a 20-metre by 200-metre strip, but efforts to find the one-metre-wide lander in high-resolution images taken by Rosetta from 20 km out have so far failed.
Finding the lander is not just a matter of closure.
Spotting the lander would also help to determine its exact position and angle, and to predict how likely Philae is to come back to life.
The craft may wake up in the coming months as the comet nears the Sun and its solar panels begin to receive more light.
"Planning for something like that is a lot of work. It would be good to know if it [will happen]," Parker noted.
The final word rests with ESA. According to the agency's manager for the mission, Fred Jansen, a decision is likely to be reached soon.
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