Possible trouble with an oxygen sensor has prompted NASA and United Launch Alliance to delay launch of the agency's $2.4 billionatop an Atlas 5 rocket to no earlier than July 30, the space agency announced Tuesday.
Already running five days late because of earlier problems, the slip to July 30 means the cumulative loss of nearly two weeks in a planetary launch window that closes in mid August. The originally advertised final launch opportunity was August 5, but it was earlier extended to August 11 and now has been stretched to August 15 and possibly a bit beyond.
In any case, NASA should have more than two weeks to get the flight off the ground before Earth and Mars move too far away from each other. Despite complications posed by coronavirus restrictions, engineers are confident they will be able to on its way.
But the stakes are high. If Perseverance misses the window because of technical issues, bad weather or some combination of factors, the flight will be delayed two years while Earth and Mars return to favorable positions in their orbits around the sun.
"When you talk about Earth and Mars being on the same side of the sun, that happens once over 26 months," NASA Administrator Jim Bridenstine said during a June 17 mission preview teleconference with reporters. "So it's very expensive, if we have to take Perseverance and put it back into storage for a period of two years, it could cost half a billion dollars."
Originally targeted for launch July 17, the flight was pushed to July 20 because of trouble with ground equipment and then again to July 22 when engineers ran into problems encapsulating the spacecraft in its protective nose fairing.
In a NASA blog post, the latest delay was blamed on "a liquid oxygen sensor line" that showed "off-nominal data" during a dress-rehearsal countdown June 22 when the Atlas 5 rocket, without its payload, was loaded with propellant. As a result, NASA said, "additional time is needed for the team to inspect and evaluate."
The Perseverance rover's launch is designed to get the spacecraft to Mars on February 18, 2021. After a fiery plunge into the martian atmosphere, the spacecraft will rely on a huge parachute to continue slowing down before a rocket-powered descent to the floor of, where an ancient river delta once deposited sediments.
Loaded with state-of-the-art instruments, cameras and even a small experimental helicopter, the six-wheeled rover will search for signs of past microbial life, collecting soil and rock samples that will be sealed in small tubes and dropped onto the surface in groups.
If all goes well, another rover will collect the samples and launch them into orbit around Mars, where they will be robotically recovered by a spacecraft provided by the European Space Agency. The samples then will be brought back to Earth around the end of the decade for detailed laboratory analysis.