/**
  * GET (AJAX), /missions/{$slug}/telemetry. Fetches all mission telemetries for a specified mission,
  * ordered by the telemetry timestamp.
  *
  * @param $slug
  * @return \Illuminate\Http\JsonResponse
  */
 public function telemetry($slug)
 {
     $telemetryQuery = Telemetry::whereHas('mission', function ($q) use($slug) {
         $q->whereSlug($slug);
     })->orderBy('timestamp', 'ASC');
     if (Auth::isSubscriber()) {
         return response()->json($telemetryQuery->get());
     } else {
         return response()->json($telemetryQuery->get(['telemetry_id', 'timestamp', 'readout']));
     }
 }