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Space & Planetary Science

New Horizons Phones Home

By Keith Cowing
NASA Watch
January 1, 2019
Filed under
New Horizons Phones Home

New Horizons Successfully Explores Ultima Thule
“Signals confirming the spacecraft is healthy and had filled its digital recorders with science data on Ultima Thule reached the mission operations center at the Johns Hopkins Applied Physics Laboratory (APL) today at 10:29 a.m. EST, almost exactly 10 hours after New Horizons’ closest approach to the object.”

NASA Watch founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.

5 responses to “New Horizons Phones Home”

  1. Michael Spencer says:
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    What an achievement! Kudos to the scientists and engineers, and American taxpayers, all making such a thing possible.

    A question, though: listening/watching the live stream, I guess I thought, in the manner of Viking, that we would see first an image of some sort- at least, that’s how I recall what happened with Viking; a picture first.

    Certainly the sort of technical checks we heard are important – necessary – but wouldn’t an image of some kind do the same thing, while simultaneously answering one of the Big Questions?

    • fcrary says:
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      You’re being optimistic. If the first thing they sent down was an image, and everything looked fine, we’d know that there were not problems with one of the instruments, at one time during the encounter. Sending down engineering telemetry first tells them that everything worked, or if not, what didn’t (along with some information to help figure out why.) I’m not involved with New Horizons, but most spacecraft operations and planning involves a lot of pessimistic, “what would we do if…” logic.

      For Viking, you may also remember how long it took for those images to come down. Viking didn’t have a camera in the way most people would think of one. It measured one pixel at a time (admittedly, through a dozen filters and/or focal lengths.) A mirror scanned that one pixel up and down to get a single column of 512 pixels, and the instrument then rotated to scan the next column. I think one of the full panoramas took over half an hour to build up.

      In fact, there was a team group picture taken with the instrument itself, and a couple of the people appeared twice. After being imaged on one side, they ran around and posed on the opposite side of the image. There’s also a running joke about how we might have missed discovering the Martian kangaroos, since they could have hopped by so quickly that we’d just have seen a blur in a couple of pixels.

      If a spacecraft can send data more quickly than it can collect it (rare), it doesn’t make the operations people nervous to interleave the science data with the engineering telemetry. The engineering stream is still coming down at nearly the same rate. I’m fairly sure that’s what Viking did. New Horizons is at the opposite end of the spectrum. It’s going to take about a year to send down the data it collected in one day.

    • Zed_WEASEL says:
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      The data transmission rate of the New Horizons from Ultima Thule is only about 1000 bauds with a pair of 12 watts radio transmitters.

      AIUI New Horizons will take about 20 months to uplinked the 7.5 GB of data from the Ultima Thule encounter.

  2. Ben Russell-Gough says:
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    So, what does everyone think: Ultima Thule-B – smaller element of a true contact binary or extremely close-orbiting moonlet?

    • fcrary says:
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      They’ve got some better images down, and it looks like a single body with two lobes. Probably two bodies which merged at some point. (One press release quoted a scientist on the team, who suggested a collision at only a meter per second or so.)

      But the two parts are resting on each other not orbiting each other. The rotation rate is 15 hours, and nowhere near orbital speeds, given the dimensions and any reasonable guess on the density. At least I can’t get anything within a factor of five.