The Long Duration Balloon Facility at Willy Field

Willy Field

Pointing test with the STO-2 telescope

The gondola and telescope inside the STO-2 hangar at LDB

Working on the STO-2 instrument inside the hangar at LDB

The purpose of my deployment to Antarctica is to help the Stratospheric Terahertz Observatory II (STO-2) team launch a science payload to look at the star forming regions in the galaxy. STO-2 will fly aboard a Long Duration Balloon (LDB). The LDB program is part of the Columbia Scientific Balloon Facility, which launches payloads all over the world.

The STO-2 team traveled to the LDB headquarters in Palestine, Texas, last July and August for a hang test to ensure the payload is ready for launch. From there it was taken apart and shipped to Antarctica. The gondola was then shipped to New Zealand on a barge and flown from New Zealand to McMurdo Station on a supply mission. The instrument was flown the whole way to McMurdo.

The STO-2 team just after passing the hang test in Palestine, Texas, in August 2015. Image credit: Christopher Walker

After shipping the payload, the team started to reassemble it in the second half of October on the ice. (I was waiting to travel to McMurdo until backup parts were completed in mid November in case important equipment failed.) It's here in McMurdo that we unpack and reassemble the payload and continue instrument testing and reintegration. 

Every day, we leave McMurdo at 7:30 a.m. and travel about six miles from McMurdo Station to the LDB facility just beyond Willy Field on the Ross Ice Shelf. We arrive between 8:05 and 8:15 depending on the driver and the mode of transportation. One of the buses is Ivan "the terra" bus, pictured below. The field camp consists of two hangars for the the payloads, a dining hall (called the galley), a bathroom facility and two smaller shelters for the Columbia Scientific Balloon Facility staff. This year, there are two payloads, STO-2 and the Gamma Ray Imager/ Polarimeter for Solar flares (GRIPS) payload. In some years there are three payloads, but never more than that. 

The LDB facility. From the left: a yellow storage facility, the GRIPS hangar (green stripe), the STO-2 hangar (brown stripe), the CSBF machine shop, the CSBF telemetry workshop, the bathroom, and all the way to the right, the yellow tent is the galley. Image credit: Jenna Kloosterman

There's a cook in the galley during lunchtime and coffee, tea, and hot chocolate whenever you need it. Furthermore, we have views of Mt. Erebus, the southern-most active volcano on Earth. Most days it is covered in clouds, but when the clouds clear, it's one of my favorite things to photograph. For a harsh continent, it's a good life!

After a full day of work, we leave LDB at 5:30 p.m. and are back in McMurdo for dinner between 6:05 and 6:15 p.m.

Boarding Ivan "the terra" bus with my colleague Jose Siles. Image credit: Jose Siles

Instrument Update:

The STO-2 gondola team has successfully tested the pointing system for the telescope, pointing on the sun and Venus. In order to do their tests, they had to open the hangar doors so the hangar could cool to the ambient temperature -- about 20 degrees F right now. The instrument team is glad that they are done until integration of the instrument with the gondola is complete.

The STO-2 instrument will be explained for a general audience in a future post. For our colleagues following us back home, the team has made progress in aligning the 1.5 and 1.9 THz local oscillators and is simultaneously conducting beam pattern measurements. The 4.7 THz channel has measured a Y-Factor (sensitivity measurement). If you are interested in the details, please communicate with us privately.


  • Jenna Kloosterman

A view of White Island (left) and Black Island (right) on the drive between McMurdo Station and Scott Base en route to the Pressure Ridge Tour

A view of Willy Field on the drive between McMurdo Station and Scott Base en route to the Pressure Ridge Tour

A view of LDB on the drive between McMurdo Station and Scott Base en route to the Pressure Ridge Tour

A first view of the pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

A view of Castle Rock taken from the pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

Me walking around the pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

A Weddell Seal lying down on the ice

A Weddell Seal rubbing his belly

A Weddell Seal who had just given birth to her cub

A Weddell Seal lying on his side

A melt pool in the pressure ridges

A melt pool in the pressure ridges

The pressure ridges between the Ross Sea Ice and the Ross Permanent Ice Shelf

View of Mt. Discovery near the Ross Ice Shelf

Every year in the summer as the sea ice melts, it is pushed up against the permanent ice shelf due to tidal forces. When this happens, the pressure from this force cracks the ice into ridges near Scott Base. Last night, I was lucky enough to walk through the pressure ridges that are formed this way with a group from the Long Duration Balloon Facility. We saw beautiful ice formations, Weddell Seals (including one that had just given birth) and melt ponds. Please see the slideshow above for the new phrase I'm coining, "Make like a seal."  Words cannot describe the scenery, so just enjoy the slideshow!



  • Jenna Kloosterman

Helium fill

The instrument I came to Antarctica to work on, the Stratospheric Terahertz Observatory II (STO-2), in the most basic terms is designed to study how stars are born. Although I'll avoid getting too technical on most of my posts here, this entry will be on the more technical side to provide an update to my colleagues back at JPL and around the world.

STO-2 uses superconducting mixers, which requires cooling it to below 9 K (that's -443 degrees F). In order to achieve this temperature, we first "precool" our cryostat to 77 K (-321 degrees F) using liquid nitrogen, and then cool using liquid helium to 4 K (-452 degrees F).  The whole process takes about 48 hours.

Today, we finished the helium fill. I participated in the fill, but you cannot see me in the picture above because I was behind the shelves on the left.

The transfer occurs from a 500 L liquid helium storage Dewar (yes, as in James Dewar, the scotch-maker -- he made whiskey to support his science habit) to the 100 L liquid helium tank on the STO-2 instrument on the right.

Although it takes about 24 hours after the fill is complete to cool everything inside the cryostat to 4 K, it was cold enough after an hour to confirm that we have five live mixers with superconducting currents! We also have five local oscillator channels working! There is still much work to be done, but overall this is a very positive sign that we are on our way to a successful mission!


  • Jenna Kloosterman

The Ob Tube

Seal resting on the sea ice

The diver's hut next to the Ob Tube

View of Ob Hill from the Ob Tube

Climbing into the Ob Tube

View from the Ob Tube: sea ice formations

View from the Ob Tube: sea ice formations

View from the Ob Tube: sea ice formations

A fish on sea ice that had formed on the window of the Ob Tube

View looking up out of the Ob Tube

I spent my first day on the ice at the Long Duration Balloon (LDB) Facility, where we work daily to prepare the STO-2 gondola and instrument. (LDB will be the subject of many future posts.)

After work, I attended a training session on outdoor skills in Antarctica. The training itself covers the flagging system (aka early GPS, so you know that you are on the trail and not walking into a snow covered crevasse) and procedures for checking out at the firehouse to let the right people know you are out hiking.

It is mostly common-sense, straight-forward information, but was required in order to walk down to the Ob Tube (Observation Tube), which I did with my friends and colleagues Chris and Kay from Arizona State University promptly after completing the training.

The Ob Tube is a hole is drilled in the sea ice and a long tube with an observation deck is inserted at the bottom. From here, one can observe the beauty of the sea. I saw only small fish and beautiful ice formations inside the Ob Tube, but a seal was resting on the sea ice outside. We also had a fantastic view of Ob Hill (Observation Hill). Enjoy the pictures from the evening!


  • Jenna Kloosterman

The C-17 after landing at Pegasus Field in Antarctica

Waiting at the US Antarctic Program Passenger Terminal to check-in

Last sunrise for 6-8 weeks!

Boarding the C-17!

Inside the C-17

Inside the C-17

Inside the C-17

Inside the C-17 - the exit was in the ceiling

The big day arrived! I set my alarm for 4:15 a.m. and I was out the door at 4:45 to take the shuttle to the United States Antarctic Program (USAP) Passenger Terminal. We put on most of our ECW at the CDC and wheeled all of our luggage into the terminal. We had to fill out a boarding card, and then your name is matched to the passenger manifest. Boarding passes are handed out with numbers. The flight crew weighs absolutely everything before it gets on the flight. Each passenger is allowed 85 lbs of personal luggage, although any ECW passengers are wearing is not counted against them. My luggage weighed in at 75 lbs -- I packed too light apparently (joking!).

Getting dressed in my ECW at the CDC before my ice flight. Image credit: Jenna Kloosterman

After checking in, we had a little time to eat a light breakfast and watch our last sunrise until we return to New Zealand. We watched a few more orientation videos and then went through a security screen. At the end of the security screen, we boarded a bus, which drove out to the tarmac to meet our plane. To my relief, it was a C-17!!! That means a plane with a jet engine, a five-hour flight time, a bathroom, and real seats. A first class military cargo plane!!! They hurried us on the plane, but I managed to hand my camera to a new friend to snap a quick picture as I boarded the plane.

Our flight last a little over five hours. The most concerning part was the "exit" sign on the ceiling! For the last two hours of the flight, we had sweeping views of the ice out the one window in the C-17.

First views of the sea ice shelf in Antarctica! Image credit: Jenna Kloosterman

We had a smooth landing at Pegasus Field. When the door to the C-17 was opened, a cold blast of Antarctic air filled the plane. Temperatures this time of year range in the 10-20 degree F range.  I realized that I had left my sunglasses on one of my checked bags, so I put on my CDC-issued goggles. I snapped a quick picture of the C-17 and then boarded Ivan "the terra" bus. An hour drive to McMurdo Station and we were dropped off at the Chalet for more on-ice orientations. At the end, we were given our room assignments. We had to pick up bedding (sheets and blankets) from Building 155 across from the dorms and our luggage at Building 140. Fortunately, there was a shuttle-bus driver to help me carry my 75 lbs of luggage from Building 155 to my dorm in Building 208. All I had to do was haul it up three flights of stairs!

Last time I was in McMurdo, I was placed in a triple room in Building 203.  Compared to that, Building 208 is the Hilton! All rooms are double occupancy, have their own sink, and share a bathroom with only one other room. It turns out I could have cut down on my packing since I did not need a robe to wear from the community shower to my room. Now I only had to share a bathroom with three other people. I will post pictures of the base and dorms in the coming weeks. So far my room remains a single, but I have been assured that I will have a new roommate with the next C-17 transport.

After unpacking, I met my colleagues coming back from the Long Duration Balloon (LDB) Facility at the galley for dinner.  More to come on LDB and meals in my posts ahead. I went to the gym for a run on the treadmill and then to the Coffee House to play games with my friends and colleagues.


  • Jenna Kloosterman


NASA’s Global Climate Change website gets a lot of user feedback. Aside from typical random Internet trolls and students posing thinly veiled attempts at getting us to write their term papers, one of the most commonly asked questions goes something like this:

“Hey, NASA, are you really sure people are causing climate change? Have you double-checked?” or “Hey, NASA, I have an idea. Maybe climate change is caused by x, y, z and it’s not really caused by humans. You should look into this.”

The short answer to this type of question is “Yes, we’ve double-, triple-, quadruple-checked. It’s science! We check and recheck a gazillion times. We’ve looked into everything you could possibly imagine and more. Before we commit to what we say, we have a strong desire to make sure it’s actually true.”

One example of how careful we have to be is when we’re analyzing the carbon dioxide in Earth’s atmosphere from space.

OCO-2 is the NASA mission designed to be sensitive enough to detect a single part of carbon dioxide per million parts of atmosphere (ppm). The way it works is super complicated. And because carbon dioxide is the most important human contribution to climate change (the biggest issue of our time) and expectations of science results were set very high, we have to be super-duper certain our measurements are correct.

The sensitivity makes it very challenging.

The instruments on OCO-2 not only measure the absolute amount of carbon dioxide at a location, but they also look for very small gradients in the distribution of CO2, the difference in the distribution of carbon dioxide between one location and another as a function of time. For example, “a gradient on and off a city is like 2 parts per million,” explained Mike Gunson, project scientist for the mission. "You see 2 parts per million from any city of modest size on up. You’re looking at the difference between 399.5 and 401.5 parts per million. So you have to be careful. Nobody’s done this over New York City, Mumbai, Beijing or Shanghai, where it could be wildly different.”

Scientists spend their lives working to get reliable data. Science is hard; it’s not a walk in the park. Everything doesn't just land in your lap. Sometimes it’s a miracle to get any data at all. People don’t often talk about the challenges of doing science, but if you could uncover the history of any project, you would probably find loads of problems, issues and challenges that come up.

After most NASA satellite launches, the instruments typically go through a validation phase, a two- or three-month period when engineers and project managers check, double-check and recheck the data coming in from the satellite to assess its quality and make sure it’s absolutely accurate before it’s released to the scientific community. But with OCO-2, “there is no validation phase,” Gunson told me, “because the measurements have such sensitivity. You’re always validating. Constant validation is an integral part of ensuring the integrity of the dataset.”

For OCO-2 to make an observation, the sky has to be clear, without clouds. Too much wind will move the carbon dioxide, so you also need quiet meteorological conditions. Then, before we can make an inference, we must assess the quality of data, which involves exceptionally large computing capacity.” Because there is so much data coming in, you end up using all sorts of analysis techniques, including machine learning, to analyze the quality of the data. OCO-2 launched in July 2014, and since this past September the data have been released to the broader science community to sink their teeth into. This means, Gunson said, “after a year of alligator-wrestling, all of a sudden we can walk it on a leash.”

Find out more about OCO-2 here and here. And check out the data here.

Learn more about NASA’s efforts to better understand the carbon and climate challenge.

I look forward to your comments.

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Clothing Distribution Center, CHC

United States Antarctic Program Terminal

United States Antarctic Program Terminal

Birds in a park in Christchurch, New Zealand

My friends Eric and Valerie, and my colleague Craig (also ice bound) in a park in Christchurch.

Flowers blooming in Christchurch

A fountain in Christchurch

The Cardboard Cathedral in Christchurch

After arriving at my hotel in Christchurch around 1 a.m., I was up and on a shuttle to the Clothing Distribution Center (CDC) at 8:15 a.m. There we had an orientation session in the US Antarctic Passenger Terminal and were issued our Extreme Cold Weather (ECW) gear. (You'll notice that those of us in science enjoy our TLAs (three letter acronyms)!) The gear includes BIG RED (my favorite parka), wind pants, hats, gloves, goggles, fleece base layers, and bunny boots.  The orientation procedures included a computer check to make sure that we don't bring any viruses that could infect the network in McMurdo as well as a form to make sure we had all received our flu vaccinations.

ECW (extreme cold weather) gear issued by the CDC (Clothing Distribution Center). Image credit: Jenna Kloosterman

After the CDC, we had the rest of the day off. I met up with my friend Eric from the University of Arizona, his wife Valerie, and my colleague Craig, who was also heading down to the ice with me. Upon my request, we wandered down to the Rose Garden. Since there are no plants in Antarctica, I really wanted one last chance to smell the roses (literally!). From there we walked through a park in bloom with beautiful flowers and birds to the center of town.

The Rose Garden in Christchurch, New Zealand. My last interaction with plant life until January! Image credit: Jenna Kloosterman

Due to a series of devastating earthquakes in 2010 and 2011 the town center was cordoned offthe last time I was in Christchurch. The city has been rebuilding slowly, and now the center has been reopened and most of the unsafe, damaged buildings have been imploded. There's a cathedral in the center (shown below) with reinforcements. It is still not safe to enter, and the only picture I could take was through a chain link fence. From there, we went to the only cathedral left standing -- called the Cardboard Cathedral. I honestly do not understand the reason it is called the Cardboard Cathedral, but it was the only thing left undamaged in the town center after the earthquakes.

A cathedral in the center of Christchurch suffered heavy damage in the earthquakes of 2010-2011. Image Credit: Jenna Kloosterman

We had an early dinner at Maharaja Indian Restaurant next to our hotel. To my disappointment, my last sunset until January was clouded over and I didn't see much. I will have to wait until I return to Christchurch for the next one. I went to bed early for a 4:45 a.m. pickup for my ice flight!


  • Jenna Kloosterman

The Sydney Opera House at Circular Quay

The train from Sydney to Circular Quay

Circular Quay, Sydney.

Jenna at the Sydney Opera House

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

Sydney Botanical Gardens

On Thursday evening, I boarded Qantas Flight 18 from LAX to Sydney, Australia. The Boeing 747 departed just after midnight and landed in Sydney on Saturday morning. I had a 9.5 hour layover in Sydney, so I went through customs in Australia, checked my large carry-on bag at the airport, and took the train to Circular Quay (the Aussie pronunciation is Circle Kay). There, I wandered around the famous Sydney Opera House and Royal Botanical Gardens.

See the slideshow above for photos of my adventures around Sydney.

After a nice afternoon, I boarded my evening flight to Christchurch, New Zealand. The flight landed around midnight, and after going through customs in New Zealand, where I had to convince the agents that my JPL hardware would not harm sheep, I finally arrived at my hotel at 1 a.m. Door-to-door travel time was around 32 hours. I was on empty and enjoyed a short night’s sleep before waking up to go to the Clothing Distribution Center the following morning. Stay tuned for my next post!


  • Jenna Kloosterman

Flight path from Christchurch, NZ to McMurdo Station

Welcome! This blog is intended to provide a behind-the-scenes look at life and work as a researcher in Antarctica. My trip begins tonight and I intend to update this blog with all of my interesting experiences as I travel to the "ice" as well as a discussion of the science we intend to do and the technology we have engineered to do it!

Traveling to Antarctica is what I imagine the experience of visiting a foreign planet would be like. With no plant life and a very arid climate, the continent feels surreal and unlike anything I have ever sensed elsewhere on Earth. I look forward to sharing my journey as we launch the Stratospheric Terahertz Observatory II (STO-2) from Willy Field!

Please feel free to contact me through my Science and Technology Personnel website with any questions and I will try my best to address them in future blog posts. As an added incentive to encourage questions from my readers, I will write postcards to the first 20 individuals and all K-12 classrooms who email me a question with their name and address.

My first trip to the ice was for STO's maiden voyage in the Antarctic spring and summer of 2011-2012. After my first trip, I learned that people have a lot of questions and misconceptions about the continent, so I want to start by addressing some of the most commonly asked questions.

First of all, geographically Antarctica refers to the southern-most continent on the planet. It is spring right now in the Southern Hemisphere and at McMurdo Station the sun is out 24 hours a day. The last sunset was Oct. 23, 2015, and the next sunset will be February 21, 2016. At McMurdo, we stay on New Zealand time (PST plus 21 hours) since it is the closest country to us.

The Arctic refers to the northern polar region. The Antarctic refers to the southern polar region.

Antarctica does not belong to any one country. Instead, it is governed by a treaty among 53 countries that preserves the continent for scientific exploration and bans any military activity. Currently, 30 countries operate bases for research. The United States has three main bases and two smaller outposts. I will be stationed at McMurdo, which has its closest approach from New Zealand and is by far the largest base on the continent with more than 100 buildings and about 1,000 people during the summer season.

In order to get to McMurdo, everyone flies commercially to Christchurch, New Zealand. (Another frequent misconception is whether I fly through Chile to get to Antarctica. There is a in fact a U.S. station on that side of the continent called Palmer Station, but it is not where I will be going.) The day after we arrive in Christchurch, also referred to as CHC (pronounced: cheech) because of the airport code, we are issued Extreme Cold Weather (ECW) gear from the Clothing Distribution Center (CDC). The CDC is where we pick up the big red jackets for which the the U.S. Antarctic Program (USAP) is famous. I loved my "big red" last time and returning it upon redeployment was such sweet sorrow. (No, we do not get to keep any of this stuff.) I am looking forward to our re-acquaintance!

Ice flights usually occur the day after visiting the CDC. If I am lucky, when I show up for my flight, it will be a C-17 plane. If not, I will fly an LC-130. What is the difference? A C-17 is basically a first-class cargo plane. It has jet engines and can reach Antarctica in around five hours. The flight crew installs real seats, and it has a bathroom, too! Although I have never been unlucky enough to fly a LC-130, my understanding is that plane is more like the Ryan Air of cargo planes -- you just sort of strap in wherever and hope for the best. If one needs to use the restroom while in flight, there is a privacy screen with a bucket. Since these planes do not have jet engines, the trip takes a whopping eight or nine hours! Similarly, weather conditions in Antarctica are unpredictable. It is possible that the flight will get canceled after all the passengers get to at the airport. Even worse is the "boomerang," in which we fly all the way to the continent, cannot land, and have to return to CHC. That means 10, or even 16 hours in flight and then you have to try again at the next available opportunity. Is anyone still interested in stowing away in my luggage as science cargo?

Upon my arrival in McMurdo, I will participate in a scientific balloon mission to launch a telescope into the stratosphere (the second major layer of Earth's atmosphere) to study how stars are born. This is the poor man's version of going to space. We will commute daily from McMurdo to an airfield located about eight miles away on the Ross Ice Shelf. We go to Antarctica for the polar vortex that sets up around the summer solstice. (There is also one in the winter, but flights are only conducted in the summer.) Each rotation around the continent lasts about 14 days, and if we launch early enough, we may continue for another rotation. The wind patterns have set up as early as December 5, but usually are not ready until after December 15. Last time I was there, the vortex was not ready until December 25, so unfortunately I do not yet know our launch date. Dear readers will have to stay tuned!

So how long will I stay down there? It really depends on when we are able to launch. Last time, because of the unusually late set up of the polar vortex and strong ground winds, STO did not launch until January 15. More factors, such as available flights back and weather conditions for planes to take off, play a role. In short, I am preparing to stay a while.

Questions? Topics related to Antarctica or STO-2 you would like to see addressed? Please email me!


  • Jenna Kloosterman

Animated gif using images from NASA's Dawn mission showing the topography of the dwarf planet Ceres

Dear Exuldawnt Readers,

Dawn has completed another outstandingly successful campaign to acquire a wealth of pictures and other data in its exploration of dwarf planet Ceres. Exultant residents of distant Earth now have the clearest and most complete view ever of this former planet.

The stalwart probe spent more than two months orbiting 915 miles (1,470 kilometers) above the alien world. We described the plans for this third major phase of Dawn's investigation (also known as the high altitude mapping orbit, or HAMO) in August and provided a brief progress report in September. Now we can look back on its extremely productive work.

Ceres wuth planetary names
This map of Ceres shows the feature names approved by the International Astronomical Union. We described the naming convention in December, and the most up-to-date list of names is here. The small crater Kait (named for the ancient Hattic grain goddess) is used to define the location of the prime meridian. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Each revolution, flying over the north pole to the south pole and back to the north, took Dawn 19 hours. Mission planners carefully chose the orbital parameters to coordinate the spacecraft's travels with the nine-hour rotation period of Ceres (one Cerean day) and with the field of view of the camera so that in 12 orbits over the lit hemisphere (one mapping "cycle"), Dawn could photograph all of the terrain.

In each of six mapping cycles, the robot held its camera and its infrared and visible mapping spectrometers at a different angle. For the first cycle (Aug. 17-26), Dawn looked straight down. For the second, it looked a little bit behind and to the left as it completed another dozen orbits. For the third map, it pointed the sensors a little behind and to the right. In its fourth cycle, it aimed ahead and to the left. When it made its fifth map, it peered immediately ahead, and for the sixth and final cycle (Oct. 12-21) it viewed terrain farther back than in the third cycle but not as far to the right.

The result of this extensive mapping is a very rich collection of photos of the fascinating scenery on a distant world. Think for a moment of the pictures not so much from the standpoint of the spacecraft but rather from a location on the ground. With the different perspectives in each mapping cycle, that location has been photographed from several different angles, providing stereo views. Scientists will use these pictures to make the landscape pop into its full three dimensionality.

Dawn's reward for these two months of hard work is much more than revealing Ceres' detailed topography, valuable though that is. During the first and fifth mapping cycles, it used the seven color filters in the camera, providing extensive coverage in visible and infrared wavelengths.

Hints at Ceres’ Composition from Color
This false-color map of Ceres was constructed using images taken in the first mapping cycle at an altitude of 915 miles (1,470 kilometers). It combines pictures taken in filters that admit light in what the human eye perceives as violet (440 nanometers), near the limit of visible red (750 nanometers), and invisible infrared (920 nanometers). Because humans are so good at processing visual information, depictions such as this are a helpful way to highlight and illustrate variations in the composition or other properties of the material on Ceres' surface. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In addition to taking more than 6,700 pictures, the spacecraft operated its visible and infrared mapping spectrometers to acquire in excess of 12.5 million spectra. Each spectrum contains much finer measurements of the colors and a wider range of wavelengths than the camera. In exchange, the camera has sharper vision and so can discern smaller geological features. As the nerdier among us would say, the spectrometers achieve better spectral resolution and the camera achieves better spatial resolution. Fortunately, it is not a competition, because Dawn has both, and the instruments yield complementary measurements.

Even as scientists are methodically analyzing the vast trove of data, turning it into knowledge, you can go to the Ceres image gallery to see some of Dawn's pictures, exhibiting a great variety of terrain, smooth or rugged, strangely bright or dark, unique in the solar system or reminiscent of elsewhere spacecraft have traveled, and always intriguing.

Occator Mosaic
Ten photos from Dawn's first mapping cycle were combined to make this view centered on Occator crater. Because of the range of brightness, pictures with two different exposures were required to record the details of the bright regions and the rest of the crater itself, as explained last month. Eight additional pictures show the area around the crater. Occator is almost 60 miles (more than 90 kilometers) in diameter. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Among the questions scientists are grappling with is what the nature of the bright regions is. There are many places on Ceres that display strikingly reflective material but nowhere as prominently as in Occator crater. Even as Dawn approached Ceres, the mysterious reflections shone out far into space, mesmerizing and irresistible, as if to guide or even seduce a passing ship into going closer. Our intrepid interplanetary adventurer, compelled not by this cosmic invitation but rather by humankind's still more powerful yearning for new knowledge and new insights, did indeed venture in. Now it has acquired excellent pictures and beautiful spectra that will help determine the composition and perhaps even how the bright areas came to be. Thanks to the extraordinary power of the scientific method, we can look forward to explanations. (And while you wait, you can register your vote here for what the answer will be.)

Scientists also puzzle over the number and distribution of craters. We mentioned in December the possibility that ice being mixed in as a major component on or near the surface would cause the material to flow, albeit very slowly on the scale of a human lifetime. But over longer times, the glacially slow movement might prove significant. Most of Ceres' craters are excavated by impacts from some of the many bodies that roam that part of the solar system. Ceres lives in a rough neighborhood, and being the most massive body between Mars and Jupiter does not give it immunity to assaults. Indeed, its gravity makes it even more susceptible, attracting passersby. But once a crater is formed, the scar might be expected to heal as the misshapen ground gradually recovers. In some ways this is similar to when you remove pressure from your skin. What may be a deep impression relaxes, and after a while, the original mark (or, one may hope, Marc) is gone. But Ceres has more craters than some scientists had anticipated, especially at low latitudes where sunlight provides a faint warming. Apparently the expectation of the gradual disappearance of craters was not quite right. Is there less evidence of flowing ground material because the temperature is lower than predicted (causing the flow to be even slower), because the composition is not quite what was assumed, or because of other reasons? Moreover, craters are not distributed as would be expected for random pummeling; some regions display significantly more craters than others. Investigating this heterogeneity may give further insight into the geological processes that have taken place and are occurring now on this dwarf planet.

Occator Topography
This color-coded topographic map of Occator crater is based on Dawn's observations in its second mapping orbit at an altitude of 2,700 miles (4,400 kilometers). Of course there is no sea level on Ceres, but the deep blue here is 5,150 feet (1,570 meters) below a reference level, and brown is 14,025 feet (4,275 meters) above it. (Brown is used in place of white for the elevation, so white can show the bright regions.) Imagine the exotic scenery here, with strangely bright areas and towering crater walls. The stereo views acquired in the third mapping orbit will reveal finer detail in the topography. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn's bounty from this third major science campaign includes even more than stereo and color pictures plus visible and infrared spectra. Precise tracking of the spacecraft as it moves in response to Ceres' gravitational pull allows scientists to calculate the arrangement of mass in the behemoth. Performing such measurements will be among the top three priorities for the lowest altitude orbit, when Dawn experiences the strongest buffeting from the gravitational currents, but already the structure of the gravitational field is starting to be evident. We will see next month how this led to a small change in the choice of the altitude for this next orbit, which will be less than 235 miles (380 kilometers).

The other top two priorities for the final mission phase are the measurement of neutron spectra and the measurement of gamma ray spectra, both of which will help in establishing what species of atoms are present on and near the surface. The weak radiation from Ceres is difficult to measure from the altitudes at which Dawn has been operating so far. The gamma ray and neutron detector (GRaND) has been in use since March 12 (shortly after Dawn arrived in orbit), but that has been to prepare for the low orbit. Nevertheless, the sophisticated instrument did detect the dwarf planet's faint nuclear emissions even in this third orbital phase. The signal was not strong enough to allow any conclusions about the elemental composition, but it is interesting to begin seeing the radiation which will help uncover more of Ceres' secrets when Dawn is closer.

To scientists' great delight, one of GRaND's sensors even found an entirely unexpected signature of Ceres in Dawn's second mapping orbit, where the spacecraft revolved every 3.1 days at an altitude of 2,700 miles (4,400 kilometers). In a nice example of scientific serendipity, it detected high energy electrons in the same region of space above Ceres on three consecutive orbits. Electrons and other subatomic particles stream outward from the sun in what is called the solar wind, and researchers understand how planets with magnetic fields can accelerate them to higher energy. Earth is an example of a planet with a magnetic field, but Ceres is thought not to be. So scientists now have the unanticipated joy not only of establishing the physical mechanism responsible for this discovery but also determining what it reveals about this dwarf planet.

Dawn HAMO Image 29
Dawn had this view near 0 degrees longitude in the northern hemisphere on Sept. 9 in its third mapping cycle at an altitude of 915 miles (1,470 kilometers). Oxo crater on the right, which shows bright material inside and out as well as a peculiar shape, is slightly over five miles (nearly nine kilometers) in diameter. The crater is named for the god of agriculture for the Yoruba people of Brazil. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Several times during each of the six mapping cycles, Dawn expended a few grams of its precious hydrazine propellant to rotate so it could aim its main antenna at Earth. While the craft soared high above ground cloaked in the deep black of night, it transmitted some of its findings to NASA's Deep Space Network. But Dawn conducted so many observations that during half an orbit, or about 9.5 hours, it could not radio enough data to empty its memory. By the end of each mapping cycle, the probe had accumulated so much data that it fixed its antenna on Earth for about two days, or 2.5 revolutions, to send its detailed reports on Ceres to eager Earthlings.

Following the conclusion of the final mapping cycle, after transmitting the last of the information it had stored in its computer, the robotic explorer did not waste any time gloating over its accomplishments. There was still a great deal more work to do. On Oct. 23 at 3:30 p.m., it fired up ion engine #2 (the same one it used to descend from the second mapping orbit to the third) to begin more than seven weeks of spiraling down to its fourth orbit. (You can follow its progress here and on Twitter @NASA_Dawn.) Dawn has accomplished more than 5.4 years of ion thrusting since it left Earth, and the complex descent to less than 235 miles (380 kilometers) is the final thrusting campaign of the entire extraterrestrial expedition. (The ion propulsion system will be used occasionally to make small adjustments to the final orbit.)

The blue lights in Dawn mission control that indicate the spacecraft is thrusting had been off since Aug. 13. Now they are on again, serving as a constant (and cool) reminder that the ambitious mission is continuing to power its way to new (and cool) destinations.

Dawn is 740 miles (1,190 kilometers) from Ceres. It is also 2.91 AU (271 million miles, or 436 million kilometers) from Earth, or 1,165 times as far as the moon and 2.93 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take 48 minutes to make the round trip.

Dr. Marc D. Rayman
3:00 p.m. PDT October 30, 2015

P.S. While the spacecraft is hard at work continuing its descent tomorrow, your correspondent will be hard at work dispensing treats to budding (but cute) extortionists at his front door. But zany and playful as ever, he will expand his delightful costume from last year by adding eight parts dark energy. Trick or treat!


  • Marc Rayman