text: function orbitalPeriod(arr) {
    const GM = 398600.4418;
    const earthRadius = 6367.4447;
    for(let i = 0; i < arr.length; i++){
      let  r = earthRadius + arr[i].avgAlt;
      let T = 2*Math.PI*Math.sqrt(Math.pow(r, 3)/GM);
      arr[i].orbitalPeriod = Math.round(T);
      delete arr[i].avgAlt;
    }
    return arr;
  }
  
  orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);