The former scientific officer with the Carter Observatory in Wellington, Graham Blow, is critical that it has dropped research to concentrate on education and tourism.
The observatory reopened during the weekend after two years and a $4.5 million refurbishment.
Although it is still the country's national observatory, most research is now undertaken by Mount John Observatory at Lake Tekapo.
Mr Blow says the country would be better off if Carter had maintained its research facilities.
But the Carter board says the observatory had lost its way between research and education and now knows what its mission is.
Chair Alick Shaw says concentrating on tourism and education will make Carter a better facility.