The Shuttle commander has practiced this procedure in NASA simulators to become proficient and skilled. In addition, the energy involved in the docking itself is small enough that the orbit of Mir is not significantly perturbed.

What are the relative sizes of the two spacecraft?
Both the Shuttle and Mir weigh roughly the same-around 200,000 pounds. While docked, the two vehicles have a combined weigh of more than half a million pounds. The shuttle is physically a smaller vehicle, with a more concentrated weight. In terms of living volume, the shuttle provides about 5,000 cubic feet - the size of a small travel trailer, while the Mir provides almost 13,000 cubic feet.

Is there a concern about static discharge when Mir and the shuttle meet?
The engineering disciplines supporting both the American and Russian space programs have analyzed the charging effects of the ionosphere. The studies indicate the potential difference between the Shuttle and the Mir, before they are in proximity, will be less than 5 volts, which is a small enough potential to be of little concern. Because of this small difference, neither the Shuttle nor the Mir needs special equipment for the reduction of electrostatic charge.

During docked operations, does overboard dumping of waste materials by one craft pose a risk to the other craft?
The Mir space station does not dump solid or liquid waste overboard. The Shuttle never dumps solid waste, only liquid (a mixture of urine and humidity condensate). We store the solid waste and take care of it after the shuttle lands. We dump the liquid waste in a "retrograde" direction, or in other words, a direction opposite to the way the spacecraft is traveling.

How long will it take for the returning U.S. cosmonaut-researcher to recover from the effects of weightlessness?
Astronauts or cosmonauts who have experienced the long duration effects of spaceflight will readapt to gravity quickly in some areas and more slowly in others. For example, weight bearing muscles are weakened by the lack of gravity, but rapidly recover to allow normal walking within a matter of days. The fine tuning of the nervous system, especially the body’s sense of balance and coordination takes longer, on the order of weeks, to fully recover. One of the systems that may take months to recover is the ability to reclaim the calcium in bone lost by the skeletal system during the long periods of weightlessness (bone mineral density). A good rule of thumb to allow for recovery to the preflight condition is to allow the person an equal amount of time on Earth to the amount of time on orbit in weightlessness.

While docked, is there an airlock between the two craft or does air travel freely between them?
There are no airlocks between the two spacecraft. But, after the two spacecraft dock, there is a small unpressurized space created between them called the "vestibule." The Mir represses this vestibule with its cabin air, then the pressure between the shuttle and Mir is equalized. After we open the hatch, a special duct is connected between the Mir and shuttle air conditioning systems. The air then passes freely between the two spacecraft.

Are there plans to attempt a flight day 1 docking with Mir?
For Shuttle-Mir missions to provide a 7-minute launch window on every day of the year the Shuttle must rendezvous on flight day 3 or flight day 4. So, for Shuttle-Mir missions there are no plans to rendezvous and dock on flight day 1. Flight day 1 rendezvous limits a launch opportunity to approximately once every third day.

For a flight day 3 or 4 rendezvous the Space Station or Mir can be located at any position in its orbit and the Shuttle has enough time and can perform the appropriate burns to catch up to and rendezvous with Mir or the Station. For a flight day 1 rendezvous this is not the case. The location of Mir or the Station at launch must be tightly limited in order for the rendezvous to occur. Thus the number of days that a launch can take place must be also be restricted. Currently a study is underway to investigate the feasibility of performing a flight day 1 rendezvous for some of the International Space Station assembly flights.

Why is NASA placing members of its astronaut corps through long-duration flight testing when similar experiments have already been done by the former Soviet and current Russian space program?
There are still many questions about the limits of radiation effects, bone loss, muscle strength and conditioning, circadian shifting, neurosensory changes, and many other physiological systems that affect not only humans in space but also on the Earth. As both the U.S. and Russia, as well as the many other countries that are participating in long duration spaceflights, continue the Mir Station program, we learn more about the individual differences (gender, spaceflight experience, age for example) that are associated with a person’s physiologic adaptation to spaceflight and re-adaptation to gravity. Perhaps as important are the learning experiences of allowing culturally different but equally isolated team members to work in the space environment together, along with the ground-based teams that support them. In order to extend our stays in space and eventually explore the solar system, we must complete our knowledge of all the intricacies of the physical and psychological effects of living and working in space.

During docked operations, does NASA Mission Control keep in touch with the Russian control center?
Yes, MCC has several communications channels to the control center at Korolyev (formerly Kaliningrad) just outside Moscow. We exchange technical data, coordinate scheduling of mission events, and give 'GO/NO GO' calls. We have interpreters at Mission Control in Houston to help our Flight Directors and engineers talk with their Russian counterparts. During Mir docking missions we have a special flight control position called the Russian Interface Operator, or RIO, to help with the exchange of data.

Since an air/sea/space ship has only one commander, who commands the Shuttle-Mir complex?
The joint Shuttle/Mir missions are wonderful examples of international cooperation, as well as the cooperative efforts of two highly skilled and experienced space operations teams. Over the years, we have developed a trust in each other's methods and judgment that allow us to work together comfortably. All decisions on operations are made after consultation between both sides, and we have yet to come to a situation where we could not come to a mutual agreement on the proper course of action to take in every circumstance. While the rules clearly dictate that each side is responsible for their own vehicle (much as the captains of two ships traveling close together retain their individual authority), the joint missions are carried out with mutual consent and coordination between all parties.

Why does the shuttle perform a flyaround maneuver after undocking from Mir?
The fly-around maneuver that has been performed on all of the Shuttle/Mir docking missions so far is not necessary from a flying standpoint - in fact, it was cut short on STS-79 when the fuel allocated for the activity was used up. The fly-around is performed for purposes of doing detailed photographic surveys of the Mir. These photos are being used by the Russian Mir team to understand the configuration and effects of aging on their station, and by the designers of the International Space Station to understand how materials and structures are affected by long-term exposure and deployment in space. The Fly-around activities have been performed on each mission because the Mir configuration has grown over the years, but now that it has reached its final form and been documented that way, future shuttle missions may likely omit the maneuver and instead separate directly from the Mir.