My "Impact" on Mars

I thought I would chime in with my story on how I became an NPR celebrity. Consider this a bit of a practice run at telling just the "interesting" and "relevant" parts of the story...

It all started very early in the morning on December 21st, sitting with Maia in my parents' living room, trying to get her back to sleep. We were watching Early Today, when they told the story of 2007 WD5, the asteroid that might hit Mars on January 30th. They said that the probability of impact had already been upgraded from 1-in-350 (0.3%) to 1-in-75 (1.3%), but that the orbit couldn't be refined further until more observations were made in early-to-mid January.

I had been planning to work about 4 hours that day anyway, so I decided to look into what was already known about this asteroid. I found that the orbit was based on 25 observations spanning 29 days (from November 20th to December 19th). From my past experience with refining orbits, I knew that there was barely enough time remaining before the potential impact to get an accurate orbit. What we know about an orbit depends strongly on the length of time covered by the observations, and as we extrapolate beyond this "observed arc" the uncertainty in our predictions grows and grows, especially if that arc is small. I knew that one way to refine the orbit without waiting until January would be to find "precovery" observations that had gone unrecognized in images taken prior to the discovery date (Nov 20). I also had access to and experience with the Sloan Digitial Sky Survey data... this was essentially the same work that I did for my PhD thesis. So I did a little exploring.

As luck would have it, the object had passed through the area of the sky repeatedly scanned by the SDSS-II Supernova Survey on November 8th & 9th, just as it was in the middle of its close approach to the Earth. It was moving along at a pretty good clip at the time (10 arcseconds/minute), so I knew that I would be looking for a fairly long streak in the images. That is, if it was there at all! Of the three runs imaged on those two days, only one was taken in the right place at the right time to catch the asteroid. Figuring this out was a fair amount of work, because the long thin stripes of the SDSS runs can take 8 hours or more to be imaged from beginning to end, and the asteroid would move more than a degree in that time. Plus, it had been a while since I had downloaded the Supernova Survey data to the University of Chicago computer where I run my code, so I had to figure it out by hand.

In the end, I narrowed the likely position to one field in one run of the SDSS data, so first I looked at that image. Here's what I found:


(Thanks to Steve Kent for putting together this "Publicity Shot," which is currently the SDSS Image of the Week.) The three colored streaks come from three separate images taken through different colored filters. I was sure I had the right object because the length of the streaks, their angle across the sky, and the rough brightness all matched the predictions. However, it was about 55 arcseconds away from the predicted position! This was how I knew that I would have a significant effect on the best-fit orbit.

I fed the calibrated images through Astrometrica to get positions for each of the streaks, and then corrected the observation times for their positions within the field. I submitted this info to the Minor Planet Center, and that was the end of my involvement! The MPC is the clearinghouse for data like this, and they calculate and publish orbits for more than 300,000 objects every day. I knew that the folks at JPL would get my data from the MPC, and calculate new odds for the Mars impact. I also knew that I'd had a significant effect on the impact probability because I had extended the observed arc by more than 40%, but I had no idea whether that probability would go up or down based on my input. I just had to wait and see.

I couldn't be patient, however, and emailed the director of the Near Earth Object Program Office at JPL. Don Yeomans had come to speak to my students at the Astro-Science Workshop back in 2004, so I had connections. I asked him to keep me in the loop regarding the calculation of the impact odds, but Don did one step better. He asked for my information, and put me into the press release! He also mentioned my name on NPR. This has spurred a lot of interest from various folks, including the UAA Advancement Office, the Anchorage Daily News, and even the Discovery Channel. So many thanks to Don! It's been a great Christmas present.

Now, I've forgotten to mention that this ties in nicely with an undergraduate research project that I'm developing for a class at UAA this coming semester. The ultimate goal is to package it for use in astronomy labs across the nation. The students examine astronomical images in order to determine the coordinates of an asteroid at a particular time, and then use the free Find_Orb software to calculate a refined orbit for the asteroid. They then use Find_Orb to add random errors to the observational data, and produce a number of asteroid "clone" orbits that represent other plausible orbital paths for the asteroid. (These are called "Monte Carlo" orbits.) Plugging all of these clones into a planetarium program like Starry Night, the students can then see that orbits can't be computed instantly when an asteroid or comet is discovered, as in Deep Impact. The predicted position of an asteroid always has some level of uncertainty, and with a large number of clones you can begin to visualize this region of uncertainty. This is essentially how JPL calculates their impact odds: they generate a large number of clones, then simulate the passage of time, and the fraction of these clones that hit Mars determines the probability of impact. I had actually given up on doing this part with my students, because the asteroid with the highest known probability of hitting the Earth (Apophis) has only a 1-in-45,000 chance of impact. This means that I would have needed some 50,000 clones, and this was infeasible with the tools I'm using. But even a 1-in-75 chance could be estimated with just a few hundred clones. Plus, the short amount of time between discovery and potential impact meant that a number of other complexities would be removed. So, I will definitely be using this object in my class project, even though the impact will have already happened (or not) by that time.

Anyway... before my contribution, here were the circumstances at Mars on the date of impact:


The horizontal-ish white line represents the orbit of Mars, and the blue line represents the best-fit orbit of 2007 WD5. The near-vertical string of white dots are JPL's clones of the asteroid. 1-in-75 of these clones hits Mars, even though the best-fit orbit is just a close approach to Mars. Here is an updated plot representing the effect of my observations (and ONLY my observations):


Now, nearly 1-in-25 of the clones hits Mars, but notice that the best-fit orbit has switched sides of Mars. The close approach would now happen on the opposite side of the planet! Also, notice the change in the scale of the image. The uncertainty region has shrunk significantly.

UPDATE: The JPL NEO Program Office has just updated the impact odds again, based on 4 observations taken on December 29th & 31st. Here are the new circumstances:


Notice that the scale has changed again, and that the uncertainty region has shrunk again as well. The impact probability is now down to 1-in-28 (3.6%), which is not very much different than before. The best-fit orbit has also moved a bit further away from the planet. If that best-fit orbit doesn't change much from here on, but the uncertainty region continues to shrink, the result will be a definite miss.

Here are a few final thoughts regarding 2007 WD5:

- It passed within 4.5 million miles of Earth on November 1st. This sounds small when you call it 0.048 astronomical units, but large if you quote it as 18.7 times the distance to the Moon. This was nothing to be concerned about, although the object bears watching in the future if it misses Mars.

- The best-fit orbit passes about 13,000 miles from the surface of Mars. If it were passing that close to the Earth, it would be only 3% of the distance to the Moon! That would be an amazing show.

- The impact on Mars would produce an explosion equivalent to 3 megatons of TNT. This is about 200 times the output of the atomic bomb dropped on Hiroshima, or 2-3 of the highest-yield weapons in the current US arsenal. Without the radiation effects, of course.

- The resulting crater would be about 1 kilometer (0.6 miles) wide. This is comparable to Barringer/Meteor Crater, which is 1.2 km wide. According to Wikipedia, that impact killed instantly everything within 2 miles, caused severe flash burns within 7 miles, leveled everything within 9-14 miles with a shock wave moving at 1,200 mph, and created hurricane-force winds up to 25 miles away. But enough dust wasn't thrown up to change the global climate. Of course, the thinner Martian atmosphere (surface pressure 1% that of Earth) could definitely change these effects.

- The impact energy would be less than that responsible for the Tunguska Blast of 1908, which was probably equivalent to 10-15 megatons of TNT.

- The time from discovery to potential impact is only a little over 2 months. If the same object were hurtling towards Earth and we had the same amount of lead-time, the only option would be evacuation of a 2,000 square mile area. That is, if astronomers had sufficient time to calculate the location of the impact! As I pointed out above, it takes time to calculate a fairly precise orbit, so the lead-time on the evacuation time could be as little as a week or two. And that's if it didn't hit in the ocean, then tsunamis would be a problem over a large coastal area. This is why I'm hoping for an impact on Mars, as a wake-up call that we need to have a plan on hand for when a space-rock is headed our way. We need a plan, we need to practice that plan, and we need an organization with the mandate to enact it when the time comes (especially if we were to try to divert it).

Andy is a NPR Celebrity

As you may know, there is an asteroid that may hit Mars at the end of January. This was all over the news the past few weeks. Over Christmas, Andy worked his magic with the archive data from the Sloan Digital Sky Survey and found the asteroid in the archive. Long story short (he can elaborate further for all those wanting to know), his findings increased the probability of the asteroid hitting Mars from 1 in 75 to 1 in 25!

Don Yeomans, the director of the Near Earth Object Program for NASA, was a guest on NPR's Science Friday yesterday. During the interview, Yeomans explained the change in probability and mentioned Andy and his research.

But, celebrity is fleeting. NASA's press release (which mentioned Andy by name) was picked up by the Associated Press. The AP butchered the story, and demoted Andy to a anonymous PhD student.

We are very proud of Andy. Its exciting to see his research be noticed by scientists and the public alike. He works hard, in this case working much of Christmas Day, and its exciting for all of us when the hard work pays off.

If you would like to listen to the NPR interview, you can do so at the Science Friday site:

http://www.sciencefriday.com/program/archives/200712281

And here's the NASA press release, which Andy provided info for:

http://neo.jpl.nasa.gov/news/news153.html

Keep your eye out for the AP story, its hit most major news outlets. Headline news ran a blurb about it, and its been on CNN's crawl. Here's a link to the wire story:

http://ap.google.com/article/ALeqM5gh4pCIVMODpYJ8IeyIaDkqK6hWIQD8TQOISO2

Home for the Holidays

We are home for Christmas and New Years. Right now we are spending time with Andy's parents. We'll be spending Christmas eve and Christmas day with the Ramsay's, then bouncing back and forth several more times before we head back to Anchorage after the new year.

We had Maia's first Christmas/ one year pictures taken, we'll post more when we have a chance.

Happy Birthday Kay!

Happy birthday to Maia's godmother, Kay. We hope you had a great day!

100 Days

As of today, we've been Alaskans for 100 days! Here are some Maia-before-and-after shots to commemorate the occasion:

Day 3

Day 8

Day 81

Day 85

Build it and they will come...

Moonstruck flock to Arizona light collector

Why I saw 15 cop cars on my morning commute...

Why did I see 15 cop cars today on my morning commute? I was apparently about an hour late for a big car chase:

http://www.adn.com/front/story/9495947p-9406887c.html

The chase ended about 2.5 miles from our house, which was about halfway through my bus-ride to the university. The location of the original carjacking (Westchester Lagoon) was about another 5 miles further away, on the west side of town, near the inlet.

This story, along with a few other morbid tales, made the electronic front page of the Anchorage Daily News a bit darker this morning than it was a few days ago. (Moose Alert!) But, they still managed to fit this story into the Top 5:

Night-riding 'poopetrator' leaves smelly evidence behind

'The average horse produces 35 or 40 pounds of a manure a day, according to a variety of sources. So this is the work of a lot of animals. "It's at least a 10-horse stable," guessed Brackbill, who said he used to clean stalls at a racetrack when he was a little boy.'

Razzberry Zerbert

We bought ourselves a new camera as an early Christmas present, and it lets us take movies with surprisingly good sound. Therefore, allow me to introduce our first home movie to appear on the blog:



Sorry it's sideways, I don't know what I was thinking!

Earthquake!

This afternoon, I was sitting in our living room working on homework when I felt the chair jiggle. Once in a while we have heavy trucks drive by that make the house shake, but this was different. It was sort of a rolling wave-like feeling. I looked around the room, and nothing was shaking except a mobile of autumn leaves we have hanging on the bookcase. The leaves were shaking at the same frequency I was feeling. It lasted about 30 seconds, maybe a bit less.

After a few mintues, I checked the Alaska Earthquake Information Center website, and sure enough, there was a 5.0 quake recorded about 60 miles North of Anchorage.

As you can see from the site, there are small earthquakes everyday. If I hadn't been sitting still (something I rarely get to do during the day, by the way!), I would not have noticed it.

South Central Alaska is known for "the big one," the Good Friday Earthquake in 1964. That one measured 9.2.

Moose Alert

Q: What do you call a bull moose tangled in Christmas lights and drunk on fermented crab apples, standing glassy-eyed and dizzy in the front yard of a downtown bar?

A: The lead story in our local paper.

Turkey Day in Anchorage

I'm in Bloomington Indiana tonight on business, but jet lag has me up way late. So, I thought I'd catch you up on our recent Thanksgiving adventures, and hope to fall asleep afterwards with a sense of accomplishment.

We were sad that we couldn't make it home to be with family for Turkey Day... I think that was a first for all of us. So the Anchorage Pucketts decided to have our own feast with all the fixings. We made mashed potatoes, sweet potatoes with marshmallows, green beans and mushrooms with almonds, cranberry sauce, and turkey gravy, all from scratch. We also made Monken's pumpkin pie (both with and without the Bisquick), and tasty Stovetop Stuffing. And to top it all off, we brined and cooked our own 14-lb turkey!

For the turkey, we followed Alton Brown's recipe. The brine was chicken stock, salt, brown sugar, and spices with a healthy dose of ice water. Mr. Turkey soaked in that for about 8 hours starting Wednesday night, in a cooler in our bathtub. Maia helped ferry the ice water to the bathroom:


Mr. Turkey came out of the oven with a viking breastplate, to protect the breast from drying out:


Mr. Turkey and friends:



Carving at the table:


Oh right, I forgot to mention the Macy's parade at 9am (tape-delayed) and some football (which we should've TiVo-delayed for prime post-feast viewing). So we had a pretty nice day!

Land of the Midnight Noon Sun

Folks have been asking lately if we've already been plunged into eternal darkness, so I thought I'd set the record straight...

First, some definitions: Civil Twilight is the time before sunrise or after sunset, when there's still enough natural light to perform normal outdoor tasks. Then sun is between 0-6 degrees below the horizon. There are two other kinds of twilight (nautical and astronomical), but I'll just call the civil one "twilight." Beyond that, I'll just point out that we have some pretty high mountains to our east, so we may not see the sun when I claim the sun "rises," but it's still pretty bright out.

Today, we have 7 hours of daylight (9:16am-4:13pm), but about 8.5 hours including twilight (8:23am-5:06pm). This means I'm walking to and from the bus in darkness, but civil dawn/dusk happens during my commute. For comparison, St Louis today had 10 hours of daylight, or about 11 hours including twilight (6:18am-5:13pm).

We won't be in Alaska for the shortest day of the year (Dec 22, Winter Solstice), but if we were we'd only have about 5.5 hours of daylight (10:14am-3:41pm), or 7.5 hours including twilight (9:11am-4:43pm). Actually, I'm nitpicking here... our shortest day in Alaska this year will only be 5 minutes longer than that! The solstice is the day the sun appears to "stand still" on the horizon, so things don't change very much in the week or two before and after.

For those of you planning to come to visit next year, you probably won't come before the Spring Equinox (Mar 21), when day and night are roughly equal. It's interesting that on that day, although Anchorage and St Louis both have about 12 hours 10 minutes of daylight, Anchorage has about 40 more minutes of twilight.

Finally, if you wait until the Summer Solstice (June 21), you'll get about 19.5 hours of daylight, or round-the-clock including twilight. In fact, the always-at-least-twilight situation lasts from June 8 - July 4. (What, no fireworks?) It actually looks like we'll be back in the "Lower 48" for some of that time, too, although we won't miss it entirely. This is one of the astronomical novelties that made me think about visiting Alaska someday, even before I got the job offer to come up here. (Why does it happen? The Earth is round and has a decent axial tilt. That's it, in a nutshell.)

If you want to explore this more for yourself, go to this site to generate your own sunrise/sunset/twilight calendars for anywhere in the world. But be sure to turn off the extra twilights and other stuff you don't want, lest it get too cluttered.

And in other astronomy news, rock guitarist Brian May of Queen has been named chancellor of Liverpool John Moores University. For those who missed it, he recently completed his PhD on "Radial Velocities in the Zodiacal Dust Cloud," 36 years after beginning the research.

Homer Sweet Homer

On the weekend of November 2-4, we ran down to Homer AK to celebrate my 30th birthday. I knew we were going to Homer, but I didn't know where we were staying. Becca kept it a secret until we pulled into the parking lot... we stayed at Alaskan Suites of Homer, which was a string of 5 little cabins sitting on a bluff overlooking Kachemak Bay. So we had privacy, but it wasn't the rustic interior you'd expect from a log cabin. In particular, it had a flatscreen TV with full cable, surround speakers, a microwave, nice bathroom, etc. If it had been a little warmer outside, we would've enjoyed the communal outdoor hot tub and fire ring, and the stainless propane grill on our back deck. We didn't get any pictures of the place ourselves, but click on their link for pix and panoramas. Below is a zoomed-in view of Augustine Volcano, from our back deck.


Unfortunately, Maia was sick for most of the trip, with a double ear infection and probably also the stomach flu. This made her a very good sleeper during the 4-hour drives there and back, but she wasn't taking fluids or her oral antibiotics. We nearly took her to the local ER, but she turned the corner on our first night there at just the right time. Oddly, in between bursts of being sick, she seemed to be having a pretty darn good time. So for the most part, it didn't stop us from getting out and doing what we wanted.

Homer is a small town (5,400), including a 5-mile-long gravel "spit" that sticks out into the bay. The spit has a boat harbor, businesses, restaurants, cute little boardwalks, RV parks, and at least one hotel. The view across the bay is pretty amazing as well, with glaciers and snow-capped mountains providing a nice backdrop for my ladies in the next pic below. Of course, it was already November and pretty cold when we got there, so the tourism was pretty dead and the fishing seemed to be as well.


Homer is HQ for a regional wildlife refuge, so we stopped in at the Alaska Islands and Ocean Visitors Center which was pretty neat. We also tried to stop at the Pratt Museum (natural history), but they were closed so they could set up for their big "Putting on the Ritz" shindig. A few restaurants were also closed due to lack of tourists (the sidewalks roll up in Homer during the off-season), but we had some excellent meals just the same. Fat Olives was a good Greek/Italian place, where I got to sample a local brew. The morning we left to head home, we had a great breakfast at the Sourdough Express. The original "Express" was a van that the owners baked bread from (and lived in), making money as they made their way to Homer, where they parked it on the Spit. It's now out front, for the kids to play in. Maia and I showed off our matching UAA hoodies inside:


The drive back to Anchorage starts on hilly ground, but then moves to higher elevation with mountains on both sides. It was pretty snowy up there! We also passed a few glacial rivers and lakes, which were a shocking teal-blue color. (I guess that's due to lack of impurities, or the particular composition of the glacial ice?) It was pretty amazing, especially because Anchorage and Homer were relatively snow-free.






See more pictures at Maia's Fotki site, under "October 2007". We'll definitely have to run back to Homer again in the spring, when there's more action, we'll be able to enjoy a water wildlife tour, and maybe do some fishing with Uncle Jeff in these rivers on the Kenai Peninsula. It's great that although we're tourists in Homer, we can come back down anytime we have a few days free.

Happy Birthday to Me!

Sledding

Over the weekend, we received our first substantial snowfall, about 7 inches. We ran out and bought a couple of sleds, and took Maia sledding for the first time. Look closely, Maia is barely visible in the last picture under all that snow!

Happy Anniversary!

730 days
9,000 total air miles
4,000 mile move
165 page thesis
18 hours of labor
1 baby girl


Two years of marital bliss: priceless

Happy 2nd Anniversary to us!

Happy Birthday Becca! (Belated)

I'm about a week and a half late getting this onto the blog, but...

Happy Birthday Becca!

She may be solidly in her 30s now, but this is still my favorite picture of her, from the old days back at the Ranch.

Happy Birthday Gramma!!

Happy 60th birthday Gramma!! We hope you have a great day!!

On the mend...

Maia is feeling better. We spent the weekend in Homer, AK (will post pictures soon!) and generally, things went pretty well. She is keeping down the medicine for the ear infection, and is sleeping through the night again YAY!

We are perfecting our diaper changing skills as she is still having a bit of- ahem- lower GI issues and requiring several diaper changes an hour at times. Hopefully this will only last another day or two!

Happy Birthdays!

A very happy birthday to daddy, who turns 30 today! Another very happy birthday to Uncle Chris! Hope you both have great days!

Maia's First Haloween

Maia's first Halloween was a memorable one. She's had a cold for over a month, and Andy and I decided to get her in to see the doctor. We were supposed to meet some other moms and babies at a coffee shop downtown for a little Halloween latte. None of the kids are old enough for trick or treating, so this was organized so we could dress them up and take them somewhere.

Maia was crabby all morning, and her morning nap was late. As a result, we were almost an hour late for the coffee date, and most of the other babies were melting down by the time we got there. I tried to take some pictures, but it wasn't working. So, shortly after we got there, we all packed up and left. Knowing that I didn't have much time before her appointment, I ran to a drive thru for some lunch. After placing my order, I realized I had no money in my wallet, so stressed and seemingly without any other options, I just drove away! I came home, threw together a random assortment of things to eat for lunch, and went back on the road to get to Maia's doctor appointment.

It was our first visit to the new pediatrician group, and I was very impressed. Everyone, including the doctors, were dressed for Halloween. Our new doctor was not in, so we saw a PA, who was great. Turns out, Maia has a ear infection in both ears. We have noticed her tugging a bit on her left ear, which was pretty severely infected, but there hasn't been any other indication of an infection. Her ears were so bad that they brought in medical students to take a look. By the time the third one was done commenting on how bad they were, I was almost in tears, feeling guilty for waiting so long to bring her in.

We leave and fill the prescription for Amoxicillin, and I give her the first dose in the early evening. After dinner, as Andy is putting her to bed, she gets sick, yuck! We were half expecting her head to spin around after it was over. Long story short, it was a rough night with her up several times, and us having to use every towel in the house. She did manage to get a good chunk of sleep in, and woke up this morning in her typical smiley mood. We fed her, and had a repeat of the night before.

After another dose of antibiotic and another round of sickness, we took her back in to see the doctor. They suggested letting her tummy rest for a day, but her ears still needed to be treated, so they gave her a round of antibiotics via 2 shots, which are good for 24 hours. :(

The plan is to try to give her the antibiotic over the weekend, while making sure she doesn't get dehydrated. If she can't tolerate it over the next few days, they'll officially declare her allergic to amoxicillin and figure out something else to give her. Meanwhile, we are heading to Homer, AK about 4 hours south of Anchorage for a weekend get-away. It's going to be an interesting weekend!

So that was Maia's first Halloween.

Comet Holmes: Update

The amazing outbursting comet (17P/Holmes) is still up there... and we still haven't seen it for ourselves. It has apparently gotten slightly fainter in the last week or so, but it's still almost as bright as the stars of the Big Dipper. The coma has gotten so large that it's very obvious to the naked eye (or so I hear!). Apparently, the physical diameter is actually larger than the planet Jupiter at this point. The outer coma glows green, due to fluorescence from the gases C2 (molecular carbon) and CN (cyanide). This is cool because it means the comet is glowing on its own (not just reflecting sunlight), but this can't be seen with the eye (only in pictures). What's also weird about this comet is that it still doesn't have a tail, despite this big cloud of gas and dust that forms the coma. The solar wind should be pushing that dust out into a tail... but as far as I can tell, that tail should be hidden behind the comet, from our perspective.

Halloween Adventures- Part One

Maia in the pumpkin patch (yes, that is snow behind her)

Maia isn't too sure about the scarecrow, who was a real guy

Sitting in the hay with pumpkins, but not taking her eyes off the scarecrows!

Yum! First scoop of ice cream at Baskin Robbins

Daddy's chocolate ice cream is the best!

On Saturday, we went to a Halloween party at our local park, Russian Jack Springs. There were games, face painting, and a haunted trail hike for older folks. For the little ones, there was a little pumpkin patch, complete with real scarecrows that played games and handed out candy. We finished up the afternoon with a trip to Baskin Robbins, where Maia got a little scoop of Peach ice cream (and some of daddy's chocolate too).

The World Without Us

I haven't read this book yet (The World Without Us), but it sounds really interesting. The author has done the usual tour of talk shows, which means I've seen him on the Daily Show as well as heard him on the Scientific American podcast Science Talk. It was on the latter that I heard an interesting tidbit. Do you know why there are no longer any large land mammals around most of the world, but there are still many in Africa? See the comments for the answer.

These images are from the book's webpage (above). This next one I find the most interesting: Within two days, subways flood. I'm amazed at how reliant we are upon our fellow human beings to hold back the forces of nature on a day-to-day basis... in this case, the pumps that hold out the water:



And I'm not sure that this one has so much to do with the absence of humans... could we hold back a glacial ice sheet during the next ice age? But it does still make you think about how temporary are the products of our civilization, on geologic timescales:



What I find most interesting about this book is that it gives its readers a glimmer of hope, even though it starts with the elimination of the human race. Apparently, it's nice to hear how quickly Mother Nature will bounce back, despite the beating she takes from us daily.