Nice work so far! The Science Team loves what we're doing and, as you might expect, have given us more work.

So, I have a few changes I need you to make to the Physics library. First, we need to know the E_{v} of both Mars and the Moon. See if you can add those additional methods for me? Here's the info you need:

`The mass of Mars is 6.39e23kg and its radius is 3.4e6m.The mass of the Moon is 7.35e22kg and its radius is 1.738e6m.`

Given that E_{vMars} (5.1 km/s) and E_{vMoon} (2.38 km/s) is already known - make sure your tests pass with these values. Yes, as you might have guessed already, the Science Team has a severe case of NIH - *Not Invented Here* syndrome. They won't rely on any bit of programming or data unless it originates from within these walls.

So here we are calculating the basics from scratch. Which is OK... you never know if you'll be the first to find an equation is incorrect!