• August 1, 2013

    CometCon Liveblog: Day 1

    by Josh Sokol

    This Thursday and Friday is the Comet ISON Observer’s Workshop: a meeting of comet scientists at the Johns Hopkins University Applied Physics Laboratory. We'll be liveblogging the meeting's presentations and discussion sessions here at ISONblog.


    Session 4: Amateur-Professional Synergy

    5:22 PM We're done for the day. Stay tuned for Part 2 of our coverage tomorrow!

    5:15 PM Discussion is winding down, and Padma Yanamandra-Fisher tries to wrap it up: "do try to find an amateur network near you." But it's not that simple, multiple commenters say. Professionals need to dictate what kind of observations are most scientifically useful. And we're heating up again!

    5:02 PM The global plan for studying ISON: "Multi-dimensional Pro-Am Synergy." The future is here, folks. But in all seriousness, everyone seems thrilled about how developed professional and amateur networks are today compared to in the past.

    4:59 PM Elizabeth Warner is providing some guidelines for good amateur-professional collaborations. In a pinch, they'd double as good dating advice. Communicate!

    4:45 PM Lou Mayo is explaining NASA's outreach goals: developing the next generation of scientists, and conveying cooling science results to the public. People respond most to events, so ISON's coming is a great opportunity to engage a wide audience.

    4:31 PM To participate, interested parties should email

    4:29 PM Matthew Knight has begun a panel discussion on the worldwide ISON observing campaign. Since ISON will be up only for a short time every night, consistent coverage requires observers – including amateurs – all over the world.

    Session 3: Nucleus

    4:11 PM Nalin Samarasinha is presenting mathematical models that show a comet's rotation changes dramatically when it's near the Sun. After (and if) ISON survives perihelion, he says, its "rotation state would be entirely different" than before. 

    3:57 PM Spitzer scientists concur: ISON is not varying much in brightness over a given day.

    3:54 PM Enter Hubble. Jian-Yiang's images from Hubble, taken in April, uncovered a sunward-facing jet and showed that ISON's nucleus is small – less than 2 kilometers in diamater. Jian-Yang also found that the comet isn't changing much in brightness. It's either not rotating, or not rotating very fast.

    3:35 PM  During Q&A: Would it necessarily be bad for the public's viewing if ISON broke up but still survived? Jian-Yiang: if so, it may even be better.

    ...and the power is out again.

    3:26 PM Jian-Yang: there's also rotation and intactness to consider. Now that ISON is active, jets of gas from the comet will start torquing it around. And if the nucleus starts falling apart, we'll want to understand why.

    3:21 PM Jian-Yang Li explains why we care about ISON's nucleus.  "The nuclear size is really the determining factor of whether it will survive or not."

    3:09 PM In the lobby there's a real-time livestream from BRRISON (remember: balloon rapid response) clean room:

    So yes, that telescope will hang under a balloon.

    Session 2: Non-Organic Volatiles

    2:35 PM Mike Mumma claims that if the comet is weakly bound together, the Sun's gravity will pull it apart and cook off the volatiles before it re-coalesces.

    2:33 PM An unrelated but super-important question came up: will ISON survive passing by the Sun? According to Matthew Knight, an expert on sungrazers, it's right on the cusp – ISON is a great experiment to see all the factors that influence sungrazing survival.

    2:29 PM The mic is getting passed around Oprah-style as a bunch of ground-based observatories share their ISON observing plans. Everything's up for debate, but the collective goal is clear: to get as complete a picture of ISON as possible.

    2:05 PM Starting in October, radio observatories will be able to measure ISON's hydroxide gas, a tracer for water. This comes up again in Q&A – when ISON will be most chemically active is also when it will be the hardest for most non-radio observatories to see.  "That's your niche," says Casey Lisse to Ellen Howell.

    1:57 PM Ellen Howell will use Arecibo, a radio array in Puerto Rico, to attempt radar detection. Why just attempt? ISON is far away, and “it depends on the size of the nucleus and rotation rate,” she says. Arecibo will send out a radio pulse at a specific frequency. If it bounces back, they've seen ISON. But if the comet's surface is rotating quickly, that signal might get washed out – diluted into adjacent frequencies by the Doppler effect.

    1:45 PM Let me stress: everyone is looking at ISON. As noted before in ISONblog, Spitzer is studying ISON's carbon dioxide in the infrared.

    1:38 PM The power is back and Dennis Boedwits is talking about Swift. Since January, the space-based Swift telescope has been imaging ISON in UV and X-ray wavelengths. If ISON breaks up, says Boedwits, "Swift can be on target within 24 hours."

    1:32 PM The power went out. Just like with the Super Bowl, conspiracy theories are swirling. Was it Beyonce's performance during the workshop lunch break?

    1:22 PM Feaga: "Tracking these molecules all the way to perihelion is important to understanding what actually might be happening to the comet."

    1:11 PM Lori Feaga is showing the rate at which volatiles were released from previous comets. Near the Sun, Comet Garradd was outgassing about 10^29 water molecules per second. (That's 790 gallons, or about four times the typical weight of a dairy cow. Thanks, Wolfram Alpha!) She's hoping to make similar measurements for ISON.

    1:03 PM After lunch it's a new session, "Non-Organic Volatiles." That's water, carbon monoxide, and carbon dioxide.

    Session 1: Hello ISON!

    11:37 AM MRO's Alan Delamere: Planning for the September 29 - Oct 1 window in which ISON will be closest to Mars is "already crucial."

    11:26 AM Enter the Martians. According to Rich Zurek, the MRO will look at ISON as the comet passes by Mars. The spacecraft is only optimized to look at surface features on Mars, though.

    11:05 AM Speaking of popping up to look at ISON: BRRISON. The BBR is "Balloon Rapid Response," and the plan is to float insturmentation into the upper atmosphere for 22 hours to measure carbon dioxide and water on the comet's surface. Also: ISON, coming from the Oort cloud, is very cold...making this not just the only mission to have been designed just for ISON, but the only mission with a name that's also a declarative sentence.

    10:46 AM NASA is launching a FORTIS: a rocket that will briefly shoot above the atmosphere and take some spectra of ISON. What? Awesome.

    10:38 AM At the close of his talk, Battams challenges the community: STEREO has to roll to capture ISON before and after perihelion. Is the science payoff worth it?

    10:34 AM Karl Battams: STEREO saw Comet Lovejoy's tail "wiggle" near the solar corona in 2011. If something happens to ISON's tail, STEREO could be there to see it.

    10:23 AM Starting in mid-October, ISON will enter the field of view of solar observatories SOHO and STEREO. They'll get the best look at ISON during the comet's closest approach of the Sun.

    10:02 AM In the workshop's intro Casey Lisse talked about observing ISON "with every telescope in the solar system." He wasn't kidding. According to team member Ron Vervack, the MESSENGER probe – currently studying Mercury – is coming through with the assist. MESSENGER will fill in gaps where the comet is too close to the Sun for Earth-based telescopes to see.

    9:45 AM The next talk focuses on the (undeniably important but less exciting) issue of archiving ISON data. It's the equivalent of comet astronomers being told to eat their vegetables; they'll be grateful for it later.

    9:28 AM A'Hearn: Based on Kohoutek and other historical examples, "my prediction is that we'll get good science but that it won't be spectacular."

    9:10 AM Mike A'Hearn asks "Is ISON unique?" The answer: sungrazing comets are commmon. Fresh-from-the-Oort-cloud comets are common. Comets detected more than 6 times farther out than the Earth's orbit? Not so much. The combination of all three is very rare.

    9:00 AM Casey Lisse kicks off the meeting by suggesting we consider ISON against Comet Kohoutek – a visually underwhelming comet that nontheless yielded tons of science. “ We shouldn’t be scared of the K-word.”