ThinkPad laptops, by 2003, were the only laptops certified for use on the International Space Station. As of 2017, they currently operate on Linux, Windows XP and Windows Vista software. NASA purchased more than 500 ThinkPad 750 laptops for flight qualification, software development, and crew training. Astronaut Senator John Glenn used ThinkPad laptops on his spaceflight mission STS-95 in 1998. ThinkPad models used on Shuttle missions include:  At least three ThinkPad 750C were left in the Spektr module of Mir when that module depressurized. Laptops used aboard the space shuttle and International Space Station feature safety and operational improvements for the weightless environment they must operate in. Modifications include velcro tape to attach to surfaces, upgrades to the CPU and video card cooling fans to accommodate for the microgravity (hotter air doesn't rise) and lower density of the cabin air, and an adapter to the station's 28 volt DC power. The ThinkPad 750 flew aboard the Space Shuttle Endeavour during a mission to repair the Hubble Space Telescope on 2 December 1993. The ThinkPad 750C's task was to run a NASA test program which determined if radiation inherent in the space environment causes memory anomalies in the 750C or generates other unexpected problems. The 755C was also used and the 760ED was tested as well as part of a Shuttle–Mir test. ThinkPads were used in conjunction with a joystick for Portable In-Flight Landing Operations Trainer (PILOT). Throughout 2006, a ThinkPad A31p was being used in the Service Module Central Post of the International Space Station and seven ThinkPad A31p laptops were in service in orbit aboard the International Space Station. As of 2010, the Space Station was equipped with 68 ThinkPad A31 computers along with 32 new Lenovo ThinkPad T61p laptops plus a dedicated IP phone which also has limited video phone capabilities. Work incorporating those laptops into the station's LAN continued into June 2011. All laptops aboard the ISS are connected to the station's LAN via Wi-Fi and are connected to the ground at 3 Mbit/s up and 10 Mbit/s down, comparable to home DSL connection speeds. From 2016, the ThinkPad line lacks a monopoly on ISS laptops, as new contract with HP now provides a small number of special modified ZBook laptops. In 2005, Chinese technology company Lenovo purchased the IBM personal computer business and the ThinkPad as a flagship brand along with it. Speaking about the purchase of IBM's personal computer division, Liu Chuanzhi said, "We benefited in three ways from the IBM acquisition.