" It 's probably not the easiest time to come in and take over the shuttle program , " Mr. Parsons said at a news conference at NASA headquarters .
" It 's probably not the easiest time to come in and take over the shuttle program , but I look forward to the challenge , " Parsons told reporters at NASA headquarters .
are devices used to send data to the microprocessor, they  convert data  from human readable form into machine readable form digital form