index.js

module.exports = function() {
  console.log('Hello Mars!')
}

package.json

{
  "name": "hello-mars",
  "version": "1.0.1",
  "description": "Hello Mars!",
  "main": "index.js",
  "dependencies": {
    
  },
  "devDependencies": {
    
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Joe Eames",
  "license": "MIT"
}