When the Russian space station and the US shuttle Discovery ended their orbital party last month, shuttle commander James Wetherbee made Mir commander Alexander Viktorenko a promise.
''The next time ... we will shake your hand, and together we will lead our world into the next millennium,'' he said.
''We are all one,'' the cosmonaut replied.
That ''next time'' came last week; the replacement crew that entered Mir March 16 included American astronaut Norman Thagard along with his cosmonaut crewmates, Vladimir Dezhurov and Gennady Strekalov.
A traditional Russian bread-and-salt greeting symbolized a new era in manned space flight. For the first time since astronaut Thomas Stafford and cosmonaut Alexei Leonov exchanged handshakes during the July 1975 Apollo-Soyuz test flight, astronaut and cosmonaut met together through the open hatch of a Russian space ship.
This time, however, the American astronaut arrived in the Russian Soyuz.
''What we have here, really, is a first step in a long relationship that I think is going to be very fruitful for both nations, Frank Culberson, deputy director of the Shuttle-Mir program told the Associated Press.
Russia and the United States have embarked on a new adventure to join their manned space flight programs and build an international station.
Dr. Thagard's three-month duty tour on Mir officially opens a three-phase venture. Seven shuttle missions to Mir and more astronaut Mir duty are planned for the next two years, in what the US National Aeronautics and Space Administration (NASA) calls Phase One. Phase Two is due to start around Nov. 1997, as the two countries begin building the core of the new space station. Phase Three follows with the expansion of the station to include three other partners -- Canada, Japan, and the European Space Agency.
Both American and Russian space officials acknowledge that their countries are taking on a big challenge and a big risk.
Over the next two years, there will be shuttle missions and Mir missions independent of the Shuttle-Mir program. But after that, the two nations will focus on building the international station. That effort -- which will be the only manned space flight action ''in town'' -- will begin to wash away the differences between their national programs. The fact that the cornerstone of the new station will be a Russian-supplied module underscores this point.
NASA administrator Daniel Goldin says he looks forward to the next two years as ''a very significant step'' that ''will provide valuable experience for the construction and operation of the international space station.'' That ''significant step'' has four main goals. Three are straightforward: to reduce technical risks in building the station, to advance study of long-duration space flight, and to conduct scientific research. The big challenge lies in the fourth goal -- learning to work together.
In a prelaunch press conference, astronaut Thagard said, ''There really have been no serious problems, and I hope and I believe that if nothing else, we have demonstrated that we can work together in a very complex area, accomplish much, and be very successful.''
Frank Culbertson, NASA's deputy director for the joint mission, told the Associated Press that the Americans have something to learn from the Russians when it comes to launches: ''We are very impressed with the efficiency of a program that launches right on time, every time.''
With long records of success and hard-learned lessons, both nations have ''the right stuff'' for manned space flight. But that ''stuff'' comes in two distinct brands. NASA officials agree with Vladimir Solovyov, director of the Mir control center at Kaliningrad, that melding the two work styles will be ''difficult.'' Yet Solovyov and other Mir officials share the determination expressed by Tommy Holloway, manager of NASA's Phase One program office in Houston, who said ''we are totally committed to the success'' of that program.
An opportunity to test that determination may come in June when Atlantis is to attempt the first shuttle docking with Mir. It will bring cosmonauts Anatoly Solovyev and Nicolai Budarin to Mir and return with Dezhurov, Strekalov, and Thagard. NASA and the Mir group have been preparing for this since the Russian-American Human Space Flight Agreement was signed Dec. 16, 1993.
This agreement and its protocols expand the Joint Statement of Cooperation in Space ratified Oct. 5, 1992. It provides for up to 10 Shuttle-Mir dockings, although NASA now plans only seven of them. It authorizes a total of 24 months Mir duty for American astronauts, and it funds $400 million of related Russian activities through the year 2000.
Mir crews have been preparing for the dockings by making adjustments to their station and testing key functions. Two failed automatic dockings last year raised concern, but a recent operation ''went smoothly,'' says Mir control center spokesman Nikolai Kryuchkov.
While shuttle officials are concerned about Mir docking ports, Mir officials are equally concerned about the shuttle's ability to dock safely. They remember that the old Apollo craft bumped the Soyuz harder than expected in their 1975 linkup. They were both small craft, so it didn't matter. The shuttle and Mir are both 100-ton structures. A rough docking could damage the station. Also, the shuttle must maneuver delicately to avoid hitting vulnerable parts of Mir.
The docking systems must line up within three inches. The shuttle can't tilt more than two degrees relative to Mir. It must approach at the snail-like speed of 1.2 inches a second -- one-quarter the speed at which the much less massive Soyuz docks. And the shuttle must dock within a four-minute time window while Mir is in contact with Russian ground control.
Discovery's crew showed it could creep in and stay oriented when it hovered near Mir last month. Discovery moved ahead of Mir. Then it came back at the station along the orbital track in which Mir was travelling. Atlantis will move up to Mir from below and thus will not have to use thrusters to slow its closure rate.
Normally, the rocket thrusters directed toward Mir would fire to slow the shuttle's approach directly. This isn't necessary as the shuttle comes up from below. Earth's gravity will do the job. Other thrusters that don't fire toward Mir can keep the shuttle on course. If one or more of these failed, the shuttle would just drift off. It wouldn't hit Mir.
Atlantis practiced this last November, using the German Crista-Spas satellite it was about to retrieve as a target. The shuttle arrived on target, on time, and with the right closure speed, showing that this will be the preferred way to approach Mir#.
Meanwhile, Mir will undergo major changes. The station is designed for expansion. Like a build-it-yourself furniture kit, factory-made modules are fitted together to provide laboratory and living spaces.
The station -- whose name translates as ''peace'' -- began in February 1986 with a single base module. This has a living and work compartment. At the aft end, a tunnel runs through an unpressurized section to the rear docking port.
At the front, a spherical unit -- the multiport node -- provides five other ports. One, directly along Mir's center line is where Soyuz transport spacecraft sometimes dock. The other four ports are oriented at right angles to Mir's center line. That's where other laboratory modules are berthed.
On April 11, 1987, cosmonauts berthed the Kvant 1 (Quantum 1) astrophysics module at the aft end of the base block. This added two more living and work compartments plus an unpressurized space for equipment. The unmanned Progress cargo spacecraft that service Mir now can dock at the rear of Kvant 1.
It was Kvant 2, launched in Nov. 1989, that showed the full flexibility of the Mir design. It added three more compartments plus an airlock for space walkers. Like all later modules, this Kvant has a lever-like arm, the Lyappa arm. This gives Mir a capability to handle objectsso large that no space station has had before.
These modules first dock at the front port that lines up with the Mir base unit center line. Then the arm grabs a socket on the outside of the multiport node. The arm then pivots the module 90 degrees and sets it in one of the radial berthing ports. Cosmonauts can later use these arms to move modules.
This is a tricky operation. The modules are massive. Kvant 2 is 13.73 meters (45 feet) long and 4.35 meters (14.3 feet) in diameter. It weighs 19,565 kilograms (21.6 tons). Yet berthing and moving these units is part of the Mir routine.
On May 31, 1990, the Mir team launched the Kristall (Crystal) module. Besides four materials processing furnaces, it added two docking ports. Since these were designed for the now discontinued Russian Buran shuttle, they are where American shuttles will dock. Discovery hovered near one of these last month.
The Russian Space Agency plans to add two more 20-ton modules this year. Spektr (Spectrum) is to launch in May. Priroda (Nature) is to join the station in November. These additions would give Mir its final four bladed ''propeller'' shape.
Even without these units, the station is massive. As now configured -- base unit plus Kvant 1 & 2 and Kristall -- the complex is 33 meters (108.3 feet) long and about 28 meters (91.9 feet) across the Kvant 2 and Kristall modules. It weighs 93,649 kilograms (103.2 tons). There are 372 cubic meters (13,137 cubic feet) of habitable space. Solar arrays provide about 27.8 kilowatts of electrical power.
This is the orbital ''home'' in which cosmonauts and astronauts will learn to adapt to one another's ways. As Norman Thagard's astronaut backup Bonnie Dunbar told a press conference last month, ''Everything we're doing now is a very good learning ground for how we'll do business in the future.'' The question now is: to what extent will the governments involved continue to fund that business?
Mir control center director Vladimir Solovyov, who has yet to receive his 1995 budget, says money is ''the main obstacle'' to the Shuttle-Mir program. NASA administrator Goldin says he ''was in shock'' over the cuts demanded by the Clinton administration, never mind what the Republican Congress might want to prune. And the 14 member-nations of the European Space Agency haven't yet made up their minds as to whether or to what extent they want to continue their share of the international space-station program. Japan and Canada are continuing their station commitments.
In Russia, hand-to-mouth funding is a way of life for government agencies. The space agency didn't get its 1994 budget until last summer. Western observers believe that, having committed itself to the joint manned flight program, the Russian government is unlikely to cut off its funding. That seems true in the US also. What shocked Goldin was the unexpected demand in January that his agency reduce its budget from the $14.26 billion requested for fiscal 1996 to $13.2 billion for the year 2000. He had expected NASA's budget to reach $14.6 billion in 1998 and then stay at that amount. Nevertheless, space-station funding is explicitly exempted from the agonizing review NASA now is making of its programs and operations.
In Europe, there's no such assurance for the station. While the ESA's original plan called for a three-part contribution -- the Columbus laboratory module, an automated cargo transport vehicle, and a crew ''life boat'' rescue craft -- the proposal had to be cut when Germany and France rejected the budget. Instead of $4.8 billion between 1996 and 2000, they said, the budget could not exceed $2.4 billion. A revised plan would delay Columbus six months, delay the cargo craft by 15 months, and drop the rescue craft. Only the Columbus laboratory has been approved so far.
Meanwhile, for astronauts and cosmonauts, the thrill of doing things together continues. As Discovery commander Wetherbee told Mir commander Viktorenko last month, ''When we both had our jets going, it was like dancing in the cosmos.'' Discovery's performance ''was like a jewel,'' Viktorenko replied.
Now members of the Shuttle-Mir team hope their politicians will share their commitment to the partnership and let the dance go on.