AP AEROSPACE WRITER

MARCIA DUNN

CAPE CANAVERAL, Fla. (AP)—Columbia’s astronauts called their next-door neighbors Tuesday—two cosmonauts on Russia’s Mir space station 84 miles away.

Shuttle commander John Blaha said he and his crew had ‘‘a good discussion’‘ via ham radio with cosmonaut Alexander Serebrov. The two spaceships were flying over Indochina at the time.

Serebrov last week became the first person to perform nine spacewalks. He and Vasily Tsibliyev have been in orbit since July and are supposed to stay up for 195 days.

Columbia’s seven astronauts have been in orbit since Oct. 18 and are supposed to stay up 14 days, paltry by Russian standards but a NASA shuttle record.

The shuttle scientists spent much of Tuesday—Day Nine of the medical research mission—injecting iron and either a hormone or saline solution into 10 of the ship’s 48 white rats.

Five rodents got the hormone and five the saline solution as a control group for the experiment, part of a space anemia study.

The naturally occurring hormone erythropoietin stimulates red blood cell production, at least on Earth. Biologists want to see whether the hormone does the same in weightlessness.

Astronauts become somewhat anemic in space due to red blood cell loss. While this is considered minor on flights lasting a few weeks, it could be a serious problem on long trips such as an excursion to Mars, that could last more than a year.

Blood was to be drawn again Wednesday from the 10 rats to see if the hormone worked.

Astronaut William McArthur Jr. endured another hourlong session in a vacuum sack that forced blood and other body fluids from his chest into his legs, where the fluids accumulate on Earth.

Experimenters want to see if the treatment keeps him from becoming dizzy once he’s back on Earth, a common complaint of returning astronauts.

And veterinarian Martin Fettman and four others took turns pointing a flashlight at targets on a large white chart, first with their eyes open and then with their eyes closed. The experiment is intended to measure changes in astronauts’ awareness of body position.

Fettman didn’t do so well.

‘‘I guess this means that nobody should ask me for directions up here,’‘ Fettman said.

‘‘Nobody asks you for directions in Houston,’‘ joked ground controller Laurence Young.