The laboratory and rover were hurtling toward the Red Planet at 8,000 mph Saturday night and were about 261,000 miles from Mars, NASA said. The landing is to take place at 1:31 a.m. EDT Monday.
"Curiosity remains in good health with all systems operating as expected," scientists said in a release.
The agency said minor software and navigation data modifications were uploaded to the unmanned spacecraft and rover Saturday afternoon from the control center in Pasadena, Calif.
Eight engines will fire up to control the spacecraft's descent into a crater. Because Earth will be below the Mars horizon from Curiosity's perspective, data can't be directly sent back. Instead, it will be relayed by the 11-year-old Mars Odyssey orbiter, NASA said.
Since its Nov. 26 launch, the project has been collecting and relaying data for 221 days on its voyage.