WICHITA, Kansas -- Former head of the Kansas Cosmosphere, Max Ary, received a three-year prison sentence Monday for stealing items from the museum he headed for 26 years.

Max Ary is no lightweight in the space world. His supporters are some of the biggest names in space exploration. But even their pleas to a judge could not keep Ary out of prison.

Ary left federal court Monday with no coment. His three-year sentence was much harsher than he had hoped for. Judge Thomas Marten said he was "sending a message" with the verdict. The prosecution calls it a necessary punishment of white-collar crime.

"Not only was it an abuse of a position of trust, but as noted, it involved some items of national historic significance," said Eric Melgren, U.S. Attorney.

Those items, sold at auction, benefited Ary’s personal account. Ary’s own successor discovered the fraud and testified against his mentor.

"This would probably be the most difficult day in our history," said Jeff Olenburger, CEO, Kansas Cosmosphere.

Ary, however, contends it was an honest mistake. He said that he inadvertently mixed his personal collection with the museum’s.

"Items that were alleged to be missing were not, in fact, missing at all," said defense attorney Lee Thompson.

While a jury didn’t buy that argument last November, some of the biggest names in space did. Three astronauts set up a website to pay for Ary’s defense while others, including Jim Lovell, wrote letters asking the judge for leniency.

"My defense is very, very simple -- and it’s that I’m not guilty," said Ary last spring. It’s a position he maintained to the end.

In court Monday, Ary begged for mercy saying that the Kansas Cosmosphere, "really was my life." He argued that probation would let him pay back the losses sooner.

The judge didn’t agree but he did issue less than the minimal jail time suggested by law.

"Recently the United States Supreme Court freed federal judges from the imprisonment of mandatory sentencing guidelines," said Wichita attorney Dan Monnat.

Ary will serve three years probation after prison time. He is free for now pending the judge’s ruling on a financial penalty for the crime.