Adam Steltzner, the NASA Engineer responsible for the Mars Curiosity Rover’s Entry Descent and Landing system, was interviewed by National Public Radio. In the article he described the jargon used in the Control Room during the final moments of the Rover’s descent on Mars. The article is here:

NASA Television published a 9 minute YouTube video of the Control Room which is viewable here:

The climax of the event occurs in the 25 seconds between 2:50 and 3:15 when the three conditions for declaring the landing a success unfolded. The audio version of the NPR article overlays sounds from the JPL Control Room with Steltzner’s comments which provides an interesting explanation for the operations speak used to choreograph and confirm the information coming back to Earth during the landing. Here is a time annotation of the three conditions mapped to the YouTube video:

  • 2:52 One of our teammates called out “tango delta nominal,” and that meant that the rover had sent a little postcard with its touchdown velocity, and where it thought it was on the surface of Mars.
  • 3:01 And I had another guy call out “RIMU stable,” which meant the rover’s not moving.
  • 3:08 And then as soon as RIMU stable was announced, Brian Schratz, who was sitting in the control room with us, was to count to 10 and confirm that the UHF telemetry stream from the rover was continuous. And that meant that the sky crane hadn’t fallen back down on top of it. “UHF is good,” Schratz reported.
  • 3:10 He said that… oh, I remember like, pointing to Al [Chen, JPL engineer], like I’m throwing success into his body. You know, like “Yes! Let’s do it, Al.

For the full experience of the tense moments just before the landing, watch the vid from the start up until approximately 3:30. The entire 9:21 minute video is worth watching for the excitement experienced as the initial images from the Rover were downloaded and displayed in real-time.

Update (08/22/2012): Doug Ellison (@doug_ellison), the Founder of, Virtualization Producer at JPL, and the Technical Director of NASA Eyes on the Solar System (, released a YouTube video which syncs the MARDI landing images with Control Room audio:

Update (08/22/2012): Jody Davis, the person who called “tango delta nominal,” has joined Twitter as @TangoDeltaNom.