7月上旬ということが決まっているだけでそれ以上の情報はまだ無いというのが公式なアナウンスですのでもう少し待ってみてはどうでしょうか?
情報収集にはメーリングリストへの登録が勧められていますのでsubscribeするといいと思います。
http://www.gatortours.com/shuttle/index.htm
STS-135 Atlantis
Americas Last Shuttle Launch
Anticipated Date: Early July +
Space shuttle Atlantis will carry the Raffaello multipurpose logistics module to deliver supplies, logistics and spare parts to the International Space Station. Atlantis also will fly a system to investigate the potential for robotically refueling existing spacecraft and return a failed ammonia pump module.
We currently do not have any further information regarding STS-135. We recommmend you subscribe to our mailing list below and you will be notified as soon as any information is available.
Please do not call our office at this time, as the information will be the same.
ありがとうございます