With little fanfare, two cosmonauts aboard the Mir research station will surpass a 326-day space endurance record this week in yet another routine but important milestone for a Soviet space program aimed at one day mounting a manned flight to Mars.

Vladimir Titov and Musa Manarov, who were launched Dec. 21, 1987, will match the current space endurance record at 3:55 p.m. MSTFriday when their time aloft will equal the record set last December by cosmonaut Yuri Romanenko of 326 days, 11 hours, and 37 minutes, according to Soviet space expert James Oberg.The Federation Aeronautique Internationale in Paris, the organization that sanctions space records, will not recognize a new endurance mark until Titov and Manarov beat the old record by at least 10 percent. If all goes well, that will occur Dec. 14, seven days shy of a full year.

The American record for long-duration space flight stands at 84 days.