His grandson, Timothy Strother, was born in Dunedin Hospital's Queen Mary Maternity Centre in May.
Timothy was four weeks early and spent the first few weeks of his life in the neonatal intensive care unit.
In order to repay the dedicated staff who cared for the baby, Mr Howington wanted to give them some items to use for fundraising.
He made his first trip to New Zealand on Tuesday and was reunited with wife Gail, who had spent the past two months helping their daughter and son-in-law Katherine and Shawn Strother before and after the birth.
In his luggage, Mr Howington had items from his workplace, the National Aeronautics and Space Administration (Nasa).
Mr Howington has worked as a space shuttle computer analyst for 12 years.
He approached his boss and asked for "something special" to give to the hospital.
He was blown away when they gave him pictures, flags, mission patches and a DVD about the Kennedy Space Centre in Orlando, Florida.
"This was my presentation to them for being so wonderful," Mr Howington said.
Also included were two signed photographs, one of a team of astronauts sent to upgrade the Hubble space telescope, and one of a team about to go on a mission to help construct the international space station.
It was "very unusual" for Nasa to distribute photographs of astronauts yet to complete a mission, Mr Howington said.
Hospital staff were very grateful to receive such a unique gift.
Neonatal intensive care unit charge nurse manager Jan Seuseu said the unit often had raffles to fundraise for items for the parent's room or to send nurses to conferences.
Proceeds from the items would be split with the maternity unit.
