While many Americans will be paying tribute to their fallen war heros this weekend and turning steaks on the barbie, NASA scientists will be busy staring at computer screens and biting their nails down to the nub.

NASA has been extremely successful over the last several years with their Mars missions, epecially when one considers that those feisty rovers, Spirit and Opportunity, designed for a 6-month lifespan are still going strong roving across the Red Planet, gathering data and transmitting their findings back to Earth three years after they first hit that rust colored Martian soil. This kind of success has got to be making NASA officials wonder if their luck will hold out now that the agency’s most ambitious Mars mission to date is about to make touchdown this Sunday.

The Phoenix Mars Lander is scheduled to make landfall this Memorial Day weekend after its 6-month journey through the cold vacuum of space and some scientists are starting to worry themselves, as space engineers are want to do from time to time whenever a mission comes close to fulfillment.

“I do not feel confident. But in my heart I’m an optimist, and I think this is going to be a very successful mission,” principal investigator Peter Smith, an optical scientist with the University of Arizona told CNN News. “The thrill of victory is so much more exciting than the agony of defeat.”

The most critical time in the entire mission consists of seven short minutes, famously designated as, “seven minutes of terror.” This is the time it takes for the Phoenix, travelling at 13 thousand miles per hour to hit the thin Martian atmosphere, pull out all the stops and have a relatively “soft” landing. Those famous expanding ballons that help cushion Spirit and Opporutnity’s landing won’t be employed for the Phoenix. It will rely on a series of parachutes to slow its descent and thrusters to help rest gently on the Martian surface.

“Everything has to go right,” said NASA Associate Administrator Ed Weiler. “You can’t afford any failures.”

“We always have to be scared to death,” said project manager Barry Goldstein. “The minute we lose fear is the minute that we stop looking for the next problem.”

This is probably wise on the part of NASA scientists to be worried and prepped to stay on their genius toes when one considers that the current track record is a 55 percent failure rate for past Mars missions.

If all goes well and the Phoenix touches down without a hitch, then after preliminary checks and balances, it will begin its primary mission of analyzing the soil surrounding the craft and permafrost of Mars’ arctic tundra, digging as deep as 3-feet into the soil for the possibility of past and present life.