NASA’s next Mars mission has now burned nearly half of its launch window

NASA says it will be forced to delay the launch of its multibillion-dollar Perseverance mission to no earlier than July 30. The Mars-bound large rover must launch on an Atlas V rocket from Cape Canaveral Air Force Station in Florida before the middle of August, or it will miss Earth’s conjunction with the red planet.

This is the third delay in the launch campaign for Perseverance, formerly known as Mars 2020, and the most concerning because a new, formal launch date has not been set.

A problem arose during a Wet Dress Rehearsal test earlier this month. During this standard prelaunch test, an Atlas V rocket is fueled with propellant and a countdown is conducted until the final moments before ignition. So what happened? “A liquid-oxygen sensor line presented off-nominal data during the Wet Dress Rehearsal, and additional time is needed for the team to inspect and evaluate,” NASA said in a statement on Tuesday afternoon, in response to a query from Ars.

A source in Florida indicated that the issue was related to the Atlas V rocket’s Centaur upper stage, which is fueled with liquid hydrogen and liquid oxygen.

Expanding launch window

The $2.1 billion rover is similar to NASA’s Curiosity rover but contains several upgrades, including the addition of a small helicopter, and it will launch on the 541 configuration of the Atlas V rocket. NASA originally set a launch window from July 17 to August 11, the optimal period for the rocket to launch, and for Perseverance to reach Mars within about six months.

The launch has since been delayed from July 17 to July 20 due to a crane issue during the stacking process; it was again delayed from July 20 to July 22. NASA attributed the latter setback to “a processing delay encountered during encapsulation activities of the spacecraft.”

The spacecraft has yet to be stacked on top of the Atlas V rocket’s first and second stages. It now seems likely that the rocket’s manufacturer, United Launch Alliance, will need to understand and address the issue with the liquid-oxygen sensor line before that activity can proceed. Once the rocket and its payload reach the launch pad, the mission will also have to contend with summertime weather in Florida, where storms along the coast are common.

On Tuesday, the space agency said it had extended the launch window to August 15 and will examine whether the launch window can be extended a few more days into August. If the Perseverance mission misses this launch window, it would be delayed 26 months, at a cost of hundreds of millions of dollars, until the next Earth-Mars conjunction in 2022.