Scott and Mark Kelly were once identical twin brothers.

斯科特和马克·凯利曾经是一对完全相同的双胞胎兄弟。

Mark is his identical twin brother who stayed on solid ground.

Mark是他一模一样的双胞胎兄弟，一直生活在地球上。

That's just one lesson learned in NASA's " Twins Study" , which allowed the organization to compare Scott Kelly's health with that of his identical twin brother Mark who stayed on Earth.

这是NASA“双胞胎研究”中得到的信息，该研究组织将斯科特·凯利的健康状况与留在地球上的同卵双胞胎兄弟马克进行比较。

Astronaut Scott Kelly for example spent an entire year aboard the space station, and as a result of time dilation, he returned back to Earth 0.01 seconds younger than his identical twin brother.

例如，宇航员斯科特·凯利在空间站上度过了整整一年，由于时间膨胀，他回到地球后比他的双胞胎兄弟年轻了0.01秒。