Map the Debris

const orbitalPeriod = arr => {
  const GM = 398600.4418;
  const earthRadius = 6367.4447;
  const root = 2 * Math.PI

  const orbitalPeriods = arr.map(elem => {
    let avgAlt = elem.avgAlt // avgAlt from current looped object
    delete elem.avgAlt // Delete avgAlt from the object
    const numerator = (earthRadius + avgAlt)**3 // Power of 3 or power of x(**x)
    const innerRoot = Math.sqrt(numerator / GM) // Square root
    const orbitalPeriod = Math.round(innerRoot * root); // Round a number to its nearest integer
    
    // Since we are using map, we return a new object of all the initial elements and the new one
    return {
      ...elem,
      orbitalPeriod
    }

  })

  return orbitalPeriods
}

orbitalPeriod([{name: "iss", avgAlt: 413.6}, {name: "hubble", avgAlt: 556.7}, {name: "moon", avgAlt: 378632.553}]);

// With love @kouqhar