According to NASA PAO: "NASA experienced two suspicious events with the Terra spacecraft in the summer and fall of 2008. There was no manipulation of data, no commands successfully sent to the satellite, and no data captured. NASA notified the Department of Defense, which is responsible for investigating any attempted interference with satellite operations. While we cannot discuss additional details regarding the attempted interference, our satellite operations and associated systems and information are safe and secure. We are complying with the guidance in the National Space Policy to protect our critical space systems and have created a working group to establish and implement an agency-wide space protection program. NASA built Landsat-7 for the U.S. Geological Survey; all inquiries regarding Landsat-7 should be addressed there."
"Larry Wortzel, one of the 12 commissioners, told Reuters on Friday. PLA is short for China's People's Liberation Army. Wortzel, a retired U.S. Army colonel and former military attache in China, cautioned that commissioners cannot be sure that the activity in question can be linked to China. But he said Beijing had conducted numerous tests on space warfare systems in 2007 and 2008. "I don't think it is a wild analytical leap to suggest that these hacks could have been part of that matrix of testing," Wortzel said in an email."
"Beijing on Monday denied a U.S. commission's claim that China may have been responsible for hacking incidents on U.S. environment-monitoring satellites, saying that the committee had "ulterior motives" in writing such a draft report."