Meaning "a week back on Earth" in a sentence

[Mohammad.Moab]

I have already joined to Using English and this is my first post. These days I'm reading 'The Martian' by Andy Weir and I have a question about meaning a sentence.

Every step of the way would have had beeping alarms, alerts, and warnings. But it was the high-oxygen warning that woke me. The sheer volume of training for a space mission is astounding. I’d spent a week back on Earth practicing emergency space suit drills. I knew what to do.

Can anyone explain the meaning of "a week back on Earth" in this paragraph? maybe it is very easy but I couldn't understand

 

[emsr2d2]

I have [STRIKE]already[/STRIKE] just/recently joined [STRIKE]to[/STRIKE] Using English and this is my first post. [STRIKE]These days[/STRIKE] I'm [currently] reading 'The Martian' by Andy Weir and I have a question about the meaning of a sentence.

Every step of the way would have had beeping alarms, alerts, and warnings. But it was the high-oxygen warning that woke me. The sheer volume of training for a space mission is astounding. I’d spent a week back on Earth practicing emergency space suit drills. I knew what to do.

Can anyone explain the meaning of "a week back on Earth" in this paragraph? Maybe it is very easy but I [STRIKE]couldn't[/STRIKE] can't understand it.

Welcome to the forum. :hi:

Please look at my corrections above.

"back on Earth" simply means "when I was on Earth". The use of "back" is used to express the distance between where the writer is now (I assume he/she is on Mars) and Earth.
"a week" is just seven days (I think you know that already).