Source

The enormous portal was held in a magic field. It had violet brilliant borders and if you looked inside it, you could see the stars.

Rainbow Dash and Twilight Sparkle were standing next to an enormous flying artifact we know as "spaceship". Luna was explaining what their mission was:

--On the other side of the portal there is a big spherical rock we call "Source". In its orbit there are two major objects: another rock smaller than Source similar to our Moon, so we'll just call it that way. The second object is the most interesting one: it's a metallic castle that we believe is called the "International Space Station". That is your objective.

--Hold on a second. - Rainbow Dash interrupted Luna - Do you want us to destroy it?!

--No! The Station is involuntarily in control of the portal because of the powerful Source magnetic field, so we can't close it from our side. You have to infiltrate there, find a way to move the station as far as you can from the portal, and come back.

--So we must not be seen...

--We don't know how they could react to our presence there, so...

An uniformed stallion appeared:

--Your Majesty, the field has been weakened, we can go through now.

--Good. - then she looked at the two young mares - It's time to go.

The spaceship's main door opened and the two ponies came in. In the pilot room, they saw only a few buttons and a microphone. Then, they heard Luna's voice from a speaker:

--We will control the spaceship from our side, so you don't have much to do here. The problem is when you have to approach the Station...

--What? - asked Twilight.

--...Do have any idea of how to use an EIA Specialized Space Movement Equipment?

--What the hay...?

--...Exactly. It's a suit that will help you move and breathe outside and inside the Station.

The spaceship started to approach the portal.

--Good luck, Rainbow Dash and Twilight Sparkle.

Then Luna stopped the transmission.

Twilight took a deep breath and thought: "How did we get here?"