New Horizons Update Boulder and Baltimore
Baltimore MD (SPX) Feb 27, 2006
Last week, we published details of the discoveries and early interpretation of Pluto's two small moons, formally called S/2005 P1 and S/2005 P2, in a pair of papers (Weaver et al. 2006 and Stern et al. 2006) in the British journal Nature. Nature is very much the Rolling Stone of the scientific community, and the discovery and interpretation of P1 and P2 won the journal's cover.
This is probably as close as the nine of us will ever get to the cover of Rolling Stone. Although this was my tenth scientific publication in Nature, it was a real rush of accomplishment that vindicated long years of searching the Pluto system for companions to Pluto and Charon.
In our back-to-back papers, we described the orbits and sizes of our two newly-discovered moons and discussed the unique architecture of the Pluto satellite system. We predicted that similarly complex satellite systems will be found routinely in the Kuiper Belt and that P1 and P2 probably generate ephemeral rings around Pluto. And we argued that P1's and P2's orbits suggest strongly they were born in the cataclysmic collision of a large KBO onto Pluto that created Charon billions of years ago.
In fact, we believe the presence of P1 and P2 in the orbital plane of Charon is very much the discovery that checkmates the 20-year-old hypothesis that Charon was born as a result of a giant impact onto Pluto.
On the same day, Feb. 23, that Nature published our papers and an accompanying "News and Views" piece by New Horizons co-investigator Rick Binzel, the nine of us on the discovery team also published a scientific bulletin called an IAU Circular. This brief communication, edited by Max Mutchler and Andrew Steffl, revealed the results of brand-new Hubble Space Telescope observations of P1 and P2, made just days before on Feb. 15.
The new HST images confirm the discovery (see above for an image from this run by HST) and show that our published orbital predictions, made last fall, were almost bang on. We expect to get one more HST observation on March 2, from which we hope to further refine the orbits of P1 and P2, and to obtain the first high-quality color measurements of the two moons.
You may also have heard we're working on official names for P1 and P2. We hope to submit those to the International Astronomical Union for formal approval this spring. In the meantime, we're referring to the pair as "Boulder" and "Baltimore," in honor of the home towns of eight of the nine people on the discovery team (and, we note, the respective locations where HST's instruments were built and where HST's scientific institute is located). S/2005 P1, the larger moon, is the one we call Baltimore. S/2005 P2, the smaller, is the one we call Boulder.
What about New Horizons? Well, it's halfway to the orbit of Mars now, and the flight mission is continuing smoothly. Last week, we conducted the launch-plus-35-day review of the engineering and operational aspects of the mission. In this formal, day-long process, the engineering leads and ops team presented the status and lessons learned from the first five weeks of flight to a review team consisting of experienced spacecraft engineers and project managers.
Also last week, we conducted the first testing of three instruments in our scientific payload: ALICE, PEPSSI, and LORRI. (And there is no truth, dear reader, to the rumor that we chose these three to begin with because they spell A-P-L.)
Although "first light" for each of these three instruments is still in the future, our tests last week proved they all survived the launch and have good power and command interfaces to the spacecraft. In addition, each instrument put its microprocessors through various paces, and ALICE unlatched and successfully tested her front door by opening it to space. All of this testing went well, and we're very happy with the engineering data that ALICE, PEPSSI and LORRI returned to Earth.
This week, SWAP and SDC will be switched on and tested, and SDC will even begin collecting data. So will PEPSSI. Starting in March, we plan to use SDC, PEPSSI and SWAP a great deal during the flight to Pluto, in order to trace out conditions in the interplanetary environment across the space of 5-billion-plus kilometers from here to the Kuiper Belt.
Also in March, we will continue instrument commissioning with increasingly complex testing of our optical and plasma components, and we'll be undertaking four very important activities with the New Horizons spacecraft itself. One I've discussed before is a course correction called TCM-3. This roughly 1.2 meter-per-second trajectory-correction maneuver will trim up our course to the Pluto keyhole at Jupiter even more precisely than TCM-1A and 1B did. TCM-3 is planned for Thursday, March 9.
Both copies of our radio science instrument, REX, will receive their initial check-outs in mid-April.
The remaining major activities for March include an upload of a few post-launch bug fixes to our command and data-handling software, the checkout of our High Gain Antenna, and installation of something called CLTSN.
CLTSN stands for Command Loss Timer Safety Net. It's a new feature of the spacecraft's autonomous fault-detection and protection system designed to act as a backup - i.e., last-ditch - recovery of the mission if the spacecraft determines it has failed to hear from ground controllers for too long a time (about 135 days). If this unlikely event ever occurs, autonomy's CLTSN switches the entire spacecraft avionics chain to the backup side, repositions the spacecraft back to a good communications attitude with the HGA dish pointed toward Earth, sets the downlink beacon to "Red 6," and fires up the receivers to await new instructions from the ground.
CLTSN, which we colloquially call the catcher's mitt, is a new layer of autonomous spacecraft recovery smarts designed to take over if the normal autonomous fault detection and recovery procedures have failed to recover the mission. This is something I insisted be added to the mission before I signed off on launch.
I hope we never have to use CLTSN, because it'll mean we're down to the last play in our playbook, but I do think it's an important new capability. After all, without CLTSN, we wouldn't have a last-ditch recovery to take over if some "unknown unknown" prevented the normal recovery processes from working as we expect them to.
You can see the next few weeks are going to be busy for New Horizons - Pluto, Charon, Boulder and Baltimore lie ahead.
Until next time.
New Horizons Set For A Comfortable Cruise Out To Jupiter And Pluto Transfer
Pasadena CA (SPX) Feb 13, 2006
NASA's New Horizons spacecraft is proceeding according to plan on its way to Pluto and the outer planets via an encounter with Jupiter next year. The following is an update from the mission's principal investigator, S. Alan Stern:
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