P-2 days: Navigating Pluto

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The Target Plane (aka B-Plane) & Arrival Time History

Where? 2.8 million kilometers to go, shuffling along at 1.2 million kilometers every day as of midnight this morning, July 12th, in Virginia Beach, Virginia. Sunday. Pluto is about 170 pixels across in the LORRI camera, but to the naked eye it’s around 10 percent the size of the full moon.

Where to? Pluto! At 7:48:54 AM, July 14th Washington D.C. time, (11:48:54 GMT), plus or minus 37 seconds or so.

Where from? The blue-green planet with the high albedo and lots of salty liquid water on the surface.

6:00 AM: The Sun rises at our hotel overlooking beautiful Lake Kittamaqundi in Columbia, Maryland. In a half-hour Jan will drive me to APL about 15 minutes south from here.

This will be our busiest day. Today we’ll nail down the arrival time (we hope), so I may not get much written. My plan is to add snatches of commentary as time allows. Watch this space …

7:19 AM: Jan drops me off at the APL back entrance and drives back to the hotel for breakfast. I come into the lab, elevate to the fifth floor of our building, and walk into the “Bullpen” where doughnut holes and coffee await. The Bullpen is a large-ish room where the Navigators and some of the Science folk hang out.

There’s an email from Jeremy saying the new radiometric tracking data is ready. Jeremy, Chris, and Dale are prime for generating solutions today, and they’re busy getting their computer runs set up. Coralie and Derek just now walk in from where they’ve been working on the optical data since zero-dark-thirty this morning in a conference room down the hall. They’ve finished ahead of schedule …

7:50 AM: We finish our daily huddle outlining what we’re up to today. There are two OpNav deliveries, Crit 36 and Crit 37, and two corresponding “OD” (Orbit Determination) deliveries combining the radiometric and OpNav data sets. At this late date, OpNav rules. It’s much more powerful than the radiometric, nailing down both our location in the target plane and our arrival time. The first solution is due at 10:06, we’ll have an hour from then to prepare a presentation for the informal “OD Conclave” meeting at 11:06, and then a formal Mission Management Meeting at 2:36 pm for announcing our delivery to the project at large.

Processing for the second OD delivery, Crit 37, starts at 11:36, and gets wrapped up in the final formal meeting ending at 12:26 tomorrow morning. We’re hoping the solution will be so non-controversial that it can be finalized earlier, around 7 PM this evening, so we can take the rest of the day off.

Dale, Chris, and Jeremy are prime for the OD solutions today. Bobby and Fred run the show, put together the slides, and give the presentations. Ken works on generating Monte Carlo statistics for the slides. Coralie and Derek (and Philip back at home base in California) get a little rest before starting the Crit 37 optical data. I watch all, absorbing sponge-like as much as I can to write omnisciently on this page, pretending to know what I’m doing, but it’s hard to keep up. I’ll tackle my own OD processing in a few minutes, shadowing Dale or Jeremy probably, but in truth I’m slow at this process, not nearly as nimble at the keyboard as the younger whippersnappers, so I mostly provide reality checks here and there as I can.

Coralie emailed us late images of Pluto and Charon, with a single comment in her text: “:)”. Craters begin to pop out.

INAV (Independent Nav) from JPL works on the other end of the Bullpen from us, being as independent as ever they can be, their job being to shadow us with their own processes and software to provide yet another reality check …

3:15 PM: The Crit 36 delivery was made. Not much movement in the target plane, but  the arrival time drifted a little earlier by about 6 seconds with a uncertainty of about plus or minus 36. Although the Navigation Team recommends that an onboard update be done, we’ll be neither surprised nor disappointed if it isn’t approved, since most of the possible trajectories (from the Monte Carlo analysis) still fit in the desired design space.

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Target Plane & Arrival Time: Crit 36 & Friends

The Crit 37 OpNav data was delivered a little over an hour ago, and the OD Navigators are working on the next set of solutions. So far, no surprises and none expected. All is well.

6:40 PM: It is done! The Crit 37 solution, which is the last one before the flyby, is finished and delivered. It’s close enough to the last one that there’s no reason to risk a failure by updating the onboard sequence. The late night meeting is cancelled. There is no update, New Horizons flies on, and Pluto looms ahead.

There is nothing more that can be done. Time for the Navigators to take a deep breath and enjoy the rest of the show!



2 thoughts on “P-2 days: Navigating Pluto

  1. Pingback: New Horizons’ Optical Navigation System | Matt Bergman

  2. Pingback: New Horizons: The “72 Second Early Arrival Error” | Matt Bergman

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