Space travel may cause long-term change in DNA, reveals NASA's Twin Study

NASA's Twin Study reveals details on how space travel affects gene expression

How will a trip to Mars affect the human body? NASA lets us peek into its 'Twins Study'!

NASA astronaut Scott Kelly calls India 'shockingly polluted'

Astronaut Scott Kelly's memoir being developed as movie

Watch: Astronaut Scott Kelly congratulates Expedition 48 Commander Jeff Williams on breaking record

Grandpa astronaut breaks US space record

NASA comes out with last video of its twin study series on Kelly brothers

Watch: NASA releases 'Metabolomics: You Are What You Eat' video!

Watch: NASA teams up with IMAX for 'A Beautiful Planet'

It's a goodbye to NASA from US astronaut Scott Kelly

US record-setting astronaut Scott Kelly to retire: NASA

See pics: NASA astronauts Tim Kopra and Tim Peake share stunning images from space!

NASA astronaut Scott Kelly consumes fresh food after a year

He's home! Scott Kelly lands in Houston, USA; welcomed by family

Scott Kelly to land in USA today; NASA to air US homecoming live!

NASA astronaut Scott Kelly welcomed back to Earth by US President Barack Obama!

Watch: NASA astronaut Scott Kelly shares space experience!

Scott Kelly holds record for US astronaut to spend most time in space

Three NASA astronauts return to Earth after completion of #YearInSpace mission