Though this might not go for Russians but for U.S. astronauts you are a scientist first, a human second, a patriot third. Belligerent associations in a setting where your lives can be compromised is foolish and unscientific. Do not bring up politics of any nature or egg them into a debate that will involve hatred with one another.
The crews on the space station are scientists, not politicians. What their leaders do has nothing to do with their jobs. Acting hostile will get them nowhere and just make for an uncomfortable time together. They should work together and focus on the task at hand. The tensions here on Earth will cool with time.
Cooperating among nations can only be beneficial, as strained tensions between countries can lead to worse things. While Ukraine has a lot of conflict going on, having mutually beneficial relations on the side will undoubtedly benefit mankind in the long run. By playing nice, it may possibly help defuse the dire situation between the US and Russia.
The U.S. and Russian space station crews should cooperate in space despite tensions in the Ukraine. Any type of positive interactions between members of the two countries could help diffuse tension in later situations, and could help the general public in both countries feel more positively towards each other. I don't know how most Russians feel about Americans, but a joint project in space could help improve relations between the two countries.
No matter what is happening politically in Europe, the two nations should of course cooperate on this peaceful exploration mission. Now more than ever is the time for joint expeditions. Perhaps a peaceful mission can pave the way to calm tensions on the ground. The two matters are mutually unconnected, and one should not hamper the other.