From May 27 till June 3, 2006 the Washington 2006 World Philatelic Exhibition was held in Washington DC Convention Center. Three letters cancelled at the Exhibition were delivered to the International Space Station (ISS). It is one of those 3 letters.
The letter addressed to Russian cosmonaut Pavel Vinogradov was delivered to the ISS by the “SoyuzTMA-9” spacecraft.
On board the ISS the letter was marked with:
the “ISS” octagonal board seal,
the “Russian Segment of International Space Station” board souvenir seal dated September 20, 2006, the day when SoyuzTMA-9 spacecraft docked to the ISS.Two round violet seals applied on the cover are privately made seals.