Mostly. The orbiters will keep listening, just in case Phoenix gathers up enough energy at just the right time to talk to them, but the chances are pretty slim. The news article says it well:
NASA can't reach Mars lander, ends mission
LOS ANGELES (Reuters) – NASA scientists said on Monday they could no longer communicate with the Phoenix Mars Lander and were calling an effective end to its five-month-plus mission on the Red Planet.
Mission engineers last received a signal from the lander on November 2, the space agency said.
As anticipated, the seasonal decline in sunshine at the space probe's polar landing site is providing too little sunlight to recharge the lander's batteries, a situation that occurred three weeks earlier than expected because of dust storms, NASA said.
"We are actually ceasing operations, declaring an end to operations at this point," said Barry Goldstein, Phoenix mission project manager at NASA's Jet Propulsion Laboratory in Pasadena, California.
NASA said the project team would keep listening for signals from the lander over the next few weeks in hopes it manages to revive itself and "phones home," but engineers believe that is unlikely due to worsening weather on Mars.
Launched in August 2007, the spacecraft landed on Mars in late May, touching down on a frozen desert at the planet's north pole to search for water and assess conditions for the possibility of sustaining life.
Phoenix has since recorded snowfall, scraped up bits of ice and found that Martian dust chemically resembled seawater on Earth -- adding to evidence that liquid water capable perhaps of supporting life once flowed on the planet's surface.
The lander also returned more than 25,000 pictures from the planet.
By late October, the probe had already surpassed its expected operational lifetime by two months.
(Reporting by Dan Whitcomb; Editing by Steve Gorman and Peter Cooney)