Everyone you admire, everyone who’s accomplished greatness, faced obstacles along the way. Think about it. Everyone. The most impressive athletes, artists or public figures found their way to success by moving through and overcoming roadblocks.

Today, as my morning jog turned into a run and then a sprint, I felt my power and strength as a woman to keep pushing forward. No. Matter. What.

At the entrance to NASA’s Jet Propulsion Laboratory where I work, there’s a sign that says “Dare Mighty Things.” The way I see it, that sign is talking directly to me. “I dare you,” it says. Not to try something easy, but to run toward the challenge of climate change with confidence, strength and courage. And now I dare all of you.



Greenland's southwestern coastline

Where ice meets water at the bottom of the sea.

A person can look at a thing over and over again before finally seeing it for the first time. That’s how I felt standing in front of an Arctic map at the University of Washington in Seattle. I gazed at the northwest coastline of Greenland, north of Baffin Bay, up where the Canadian Queen Elizabeth Islands come close to Greenland.

Of course I’ve looked at Arctic maps before, from a zillion different angles. Normally I’m the one pointing and explaining. “Look at how small the Arctic area is. It’s a shallow sea, mostly surrounded by continents and islands where sea ice forms and gets trapped,” I say, encouraging folks to get as excited as I am about this remote part of the planet that’s chopped up, spread out and distorted by most maps. But this time, standing next to James Morison, senior principal oceanographer from the University of Washington, I was the one listening, looking closely and being amazed.

We were in the hallway of the Applied Physics Laboratory’s polar science wing, taking a break between Oceans Melting Greenland (OMG) science team presentations. The walls were lined with photos of teams out on glaciers, ice drilling equipment, ice sheets of the world and grand ice-covered landscapes. Ice, ice and more ice, and penguins. There were pictures of polar bears and narwhals, too. But Greenland’s jagged coastline had me captivated. The islands, the convolutions, the fjords: phenomenal, mindboggling. I couldn’t take my mind off it.

Greenland's northwestern coastline in September 2015 during Phase 2 of the TerraSond / Cape Race Bathymetry survey. Credit: NASA/JPL.
Greenland's northwestern coastline in September 2015 during Phase 2 of the TerraSond / Cape Race Bathymetry survey. Credit: NASA/JPL.
Are you desperate to grab a map right this second to have a look? Do it.

But the Oceans Melting Greenland team is doing more than looking at maps of Greenland. Way more. “We’re trying to look under the ice,” Principal Investigator Josh Willis told me. “What is the sea floor like under there? What is the interface between where the bottom of the ice sheet reaches out over the seawater and down into the ocean?”

The seawater around 400 meters (1,312 feet) deep is 3 to 4 degrees Celsius (5 to 8 degrees Fahrenheit) warmer than the water floating near the sea surface. And the shape of the sea floor (bathymetry) influences how much of that warm, subsurface layer can reach far up into the fjords and melt the glaciers. The OMG team wants to measure how much of that warm water could be increasing due to climate change.

What will the future hold? Will we see 5 feet of sea level rise … or 10 or 20?

And even though Greenland feels untouched and remote, feels so “Who cares?” we all need to be concerned about its complex coastline and the rapid pace of its melting ice sheet. NASA’s GRACE satellites observed Greenland shedding a couple trillion—with a “t”—tons of ice over the last decade, and the rate of melt is increasing. So that winding coastline and those unfamiliar fjords have already impacted all of us—yes, that means you—undoubtedly, no matter how far away or how far inland you reside.

As each of the dozen or so OMG members took his or her turn updating the team on their most recent topography, temperature and salinity measurements, I noticed a trend. Everyone kept repeating the phrases “never been surveyed before,” “it’s a very tough area,” and “these fjords are so very small, they have no names and have never been visited before.” They are literally exploring these unknown areas in detail for the first time.

My mind drifted off to the edge of that unimaginably complicated winding coastline, that unknown place where ice meets water meets seafloor, where the ice is melting as fast as we can measure. And I had to stop the group to ask why. Specifically, why is it so tough? Why has no one been there before? It turns out this area is difficult to navigate because big chunks of remnant sea ice clog up the water. The crew has to snake in between floating icebergs and weave in and out of the narrow fjords. It’s rather treacherous. And weather conditions can be challenging up there. The other reason this area is so unknown is that the glacier has retreated so recently that the coastline is changing as fast or even faster than we can study it.

Last summer, a small group that included UC Irvine graduate student Michael Wood sailed on the M/V Cape Race deep into some of the most jagged areas around southeastern Greenland, which, according to Co-Investigator Eric Rignot, is the “most complex glacier setting in Greenland.” After more than 7,871 kilometers (4,250 nautical miles) and more than 300 Conductivity, Temperature Depth (CTD) casts, the first bathymetric survey was completed.

Over the next five years, OMG will measure the volume of warmer water on the continental shelf around Greenland to figure out whether there is more warm water entering the fjords and increasing ice loss at the glacier terminus.

Greenland's northwestern coastline in September 2015 during Phase 2 of the TerraSond / Cape Race Bathymetry survey. Credit: NASA/JPL.
Greenland's northwestern coastline in September 2015 during Phase 2 of the TerraSond / Cape Race Bathymetry survey. Credit: NASA/JPL.

Here are some details about the OMG plan:

  • Every year for four years, survey glacier elevation near the end of marine-terminating glaciers around Greenland’s coastline using NASA’s airborne synthetic aperture radar altimeter GLacier and Ice Surface Topography INterferometer (GLISTIN-A).
  • Every year for five years, deploy 250 Aircraft eXpendable Conductivity Temperature Depth (AXCTD) probes to measure temperature and salinity of the waters around Greenland from one of NASA’s G-III aircraft.
  • Use a ship with multi-beam sonar to measure bathymetry of the seafloor up very close to the extremely jagged coastline of Greenland, as well as a small vessel with a single beam going up into small places, driving up fjords and getting as close to glaciers as is safe.
  • Collect gravity measurements from small planes in Northwest, Southeast and Northeast Greenland to help map the sea floor in places the ships cannot go.

Find out more about Oceans Melting Greenland.

View and download OMG animations and graphics.

Thank you for your comments.


Oceans Melting Greenland is part of NASA Earth Expeditions, a six-month field research campaign to study regions of critical change around the world.?



Viking 1 Landing Photos

Before personal computers, web sites, email, smart phones, and social media were commonplace, JPL posted mission photos on a bulletin board in the mall, with a caption by each photo.  This was the only way for most employees to see the images that were released to the public.

In July 1976, JPL celebrated the arrival of the Viking 1 lander on Mars.  Many images were received from the Viking orbiter and lander during that summer and some were assembled (by hand) into panoramas and mosaics.  Photos were displayed by closed-circuit television during the landing event to groups of visitors in a few locations on Lab, and were filmed or broadcast by visiting news crews.  Hard copy photos were distributed to the news media.  A small set of images from each JPL mission was typically selected for distribution to all JPLers, along with a letter of congratulations and thanks for their contributions. Decades later, many of these photographs and lithographs have found their way to the JPL Archives.

For more information about the history of JPL, contact the JPL Archives for assistance.  [Archival and other sources:  JPL photo albums and indexes; JPL Annual Reports, and The Viking Mission to Mars.]


  • Julie Cooper

Map of Earth showing regions of methane and carbon dioxide

The average amount of carbon dioxide in Earth’s global atmosphere is 400 parts per million (ppm).

The average amount of carbon dioxide in Earth’s global atmosphere is 400 parts per million (ppm), but according to Ken Davis, Atmospheric Carbon and Transport - America (ACT-America) principal investigator, areas near agriculture like cornfields can consistently run about 10 ppm lower in the summertime. That’s because terrestrial ecosystems like trees and corn suck about a quarter of our carbon dioxide emissions out of the atmosphere.

Thank you, trees and corn.

But wouldn’t you like to know exactly where this is happening, and by how much? Does the amount of carbon dioxide taken up by farms and forests change across seasons, across weather patterns? And even more important, will these ecosystems still be able to continue pulling our carbon pollution out of the atmosphere for us 50 years from now, especially if our climate changes unfavorably for these biological systems? Will dead trees start releasing carbon dioxide back into the atmosphere? It’s as if the forests and farms are “Get Out of Jail Free" cards and we’re not sure for how long the free pass will be good.

See, scientists have been measuring carbon dioxide and methane on a global basis. But we’d like to understand the mechanisms that are driving biological sinks and sources regionally. And we’d like to measure these greenhouse gases so that we can know if and when we’ve succeeded in reducing our emissions.

Davis explained that right now, most of our knowledge about regional sources of methane and carbon dioxide comes from a ground-based network of highly calibrated instruments on roughly 100 towers across North America. Yet being able to understand the regional sources and sinks of these two greenhouse gases is crucial to being able to predict and respond to the consequences of a changing climate.

“We don’t have all the data we need? That’s unbelievable,” I said, shocked. How is that even possible in 2016?” But Davis kept repeating: “No, we definitely don’t have enough data density.” Indeed, we take our data for granted, even as we continue burning fossil fuels.

The Atmospheric Carbon and Transport–America, or ACT-America, campaign will observe greenhouse gas transport with instruments on two NASA aircraft including the C-130H from NASA's Wallops Flight Facility in Wallops Island, Virginia.
The Atmospheric Carbon and Transport–America, or ACT-America, campaign will observe greenhouse gas transport with instruments on two NASA aircraft including the C-130H from NASA's Wallops Flight Facility in Wallops Island, Virginia.
That’s where NASA’s ACT-America comes in. ACT-America is an airborne Earth Venture Suborbital mission that will measure sources and sinks of carbon dioxide and methane over three swaths of the United States during all four seasons for five years from NASA’s modified C-130 and B-200 aircraft. The planes are fitted with remote sensing instruments, including a CO2 Lidar, cavity ring-down spectrometers to measure carbon dioxide and methane “in situ” on the aircraft and flasks to capture air samples around the plane.

The Atmospheric Carbon and Transport–America, or ACT-America, campaign will observe greenhouse gas transport with instruments on two NASA aircraft including the King Air B-200 from NASA's Langley Research Center in Hampton, Virginia.
The Atmospheric Carbon and Transport–America, or ACT-America, campaign will observe greenhouse gas transport with instruments on two NASA aircraft including the King Air B-200 from NASA's Langley Research Center in Hampton, Virginia.
“The accuracy standard we hold our instrument to is one tenth of a part per million,” Davis told me. “That’s hard. You can’t just go down to the store and get a carbon dioxide sensor that does that.”

Technician Jim Plant checks an instrument rack aboard the King Air B-200 at NASA's Langley Research Center in Hampton, Virginia, in preparation for the first ACT-America flights this month.
Technician Jim Plant checks an instrument rack aboard the King Air B-200 at NASA's Langley Research Center in Hampton, Virginia, in preparation for the first ACT-America flights this month.
We know a lot about the quantity of anthropogenic carbon dioxide emissions because it’s easy to count them at the pump and at the power plant. And scientists also take measurements of global carbon dioxide and other greenhouse gases from ground-based towers, mountaintops and satellites. But measuring methane, another important greenhouse gas, is more complicated. Methane that comes from biological systems like wetlands, rice paddies, cattle farms and landfills is not very well quantified. We don’t have monitors on rice paddies or landfills. There’s no reporting system. And methane from fossil fuel production and distribution typically comes from a leak.

So on July 18th, Davis and his team will head out to the first of three study areas for a two-week stint. These three regional study areas were chosen to represent a combination of weather and greenhouse gas fluxes across the U.S. The Midwest has a lot of farms and therefore has an agricultural signal. It’s also the origin point of cyclones. The Northeast forests are different than the Southern coastal forests, which will give us both types of data. The Southern coastal weather, storms and flow off the Gulf of Mexico are unique, and there’s oil and gas development in both the Mid-Atlantic and Southern regions. This means that between these three study areas, the team will be able to observe a wide range of conditions.

In addition to measuring regional sources and sinks of carbon dioxide and methane, ACT-America is planning to fly on a path right underneath NASA’s OCO-2 satellite to measure air characteristics, provide calibration and validation and make OCO-2’s data more useful. The mission will also fly through a variety of weather systems to find out how they affect the transport of these greenhouse gases.

Davis told me he’s “excited to fly through cold and warm fronts and mid-latitude cyclones to find out how greenhouse gases get wrapped up in weather systems.”

Find out more about ACT-America here

Thank you for reading.


ACT-America? is part of NASA Earth Expeditions, a six-month field research campaign to study regions of critical change around the world.



NASA's Student Airborne Research ProgramYoutube video

NASA's Student Airborne Research Program trains future climate scientists.

We receive a lot of questions, especially from students, asking us for information about how to get a job at NASA. Well, there’s more than one way to get hired here. But one of the most awesome methods we have of training young scientists and preparing them for potential hire here (or a great position anywhere) is by recruiting university undergraduates for our Student Airborne Research Program (SARP)

SARP is our eight-week summer program for college seniors with academic backgrounds in engineering or physical, chemical or biological sciences and an interest in remote sensing. We select about thirty students based on their academic performance, their interest in Earth science and their ability to work in teams. These students receive hands-on research experience on NASA's DC-8 airborne science laboratory. Yup, they get to fly on a modified NASA plane out of NASA’s Armstrong Flight Research Center, in Palmdale, Calif., where they help operate instruments onboard the aircraft and collect samples of atmospheric chemicals.

Did I already say “awesome”? Oh right, I did. Well, I’ll say it again: Awesome.

Many students apply hoping to gain more research experience for graduate school. The whole air sampling team, which is exactly what it sounds like, collects air from around the plane in canisters as it’s flying through different locations and altitudes at different times. The air enters the plane from the outside through an inlet, a pipe sticking out of the plane. The student scientists open the canisters, allowing air from outside the airplane to suck into the can. Then they take the air samples back to the lab at the University of California, Irvine, for analysis and interpretation.

SARP students analyze the air samples for hydrogen, carbon monoxide, carbon dioxide, methane, hydrocarbons, nitrates, oxygenates and halocarbons. Research areas include atmospheric chemistry, air quality, forest ecology and ocean biology.

Once the airborne data has been collected and analyzed, the students make formal presentations of their research results and conclusions. Over the past seven years, the program has hosted 213 students from 145 U.S. colleges and universities. And this year we look forward to helping our latest crop of SARP students gain research experience on a NASA mission, work in multi-disciplinary teams and study surface, atmospheric and oceanographic processes. 

Find out what SARP students thought about their experience here.

Find out more about SARP and other Airborne Science Programs here.

Thank you,


SARP is part of NASA Earth Expeditions, a six-month field research campaign to study regions of critical change around the world.



Crushable Materials Tests for Surveyor

Even before Hughes Aircraft Company was selected as the contractor that would design and build the Surveyor landers, JPL began conducting tests of materials that would help to cushion the impact of a moon landing.  It was to be a soft landing, in contrast to the Ranger crash landings, but there would still be a drop of about 13 feet, where the Surveyor vernier engines would cut off and the lander would free fall to the surface of the moon.

The lander had a tripod structure, with hydraulic shock absorbers in the landing legs.  JPL also planned to use three blocks on the underside of the lander, one near each leg, that would absorb some of the impact.  Various materials, sizes, and configurations were tested, including aluminum tubes and sheets, some formed into a hexagonal honeycomb pattern.  The JPL Photolab took dozens of photos for the Engineering Research Section (354) which are identified simply as “crushable materials” and they show several series of tests completed in 1960-1962.  The results were reported in JPL’s bimonthly Space Programs Summaries and other technical reports.

For more information about the history of JPL, contact the JPL Archives for assistance.  [Archival and other sources: Surveyor Mission Reports; various Space Programs Summaries; RS36-5, vol. 2;  Section 354 photo indexes, JPL telephone books and organization charts.]


  • Julie Cooper

This underwater photo of a sea slug was captured with a close-up lens in Monterrey, Calif., by my first SCUBA instructor, Thomas Chapin circa 1985.

At 8 p.m. after a long day of work in the Houston humidity, Derek Rutavic, manager of the NASA Gulfstream-III that will head back to Greenland this fall, and I were in the back of the plane singing One Direction’s "Drag Me Down" over the high frequency radio system. It was stifling hot, getting dark and we were tired and hungry.

But Oceans Melting Greenland (OMG) Principal Investigator Josh Willis and Project Manager Steve Dinardo, too busy to take off their sweaty fire retardant flight suits, were troubleshooting electronics at two racks of computers, and they’d asked Rutavic to get on the headset to find out if the headset noise was interfering with the high radio frequency data signal the ocean science probes were sending back to the plane. Rutavic sat on an empty science probe container, while I lounged on one of the sofas singing along in awe of the amount of hard work this team was putting in.

We’d been up early, flown multiple test flights, worked through lunch. And all of this after days and days of maintenance, and weather delays, and more hard work after more hard work. Earlier in the day, NASA T-38 supersonic jet pilot Bill Rieke flew mind-bogglingly close to the G-III to photograph the science probe deployment and determine if the technique of launching the probes through a hole in the bottom of the plane would succeed. And yes, it did. But that success merely signaled the OMG team to continue working.

And I understood exactly why this team kept going, kept moving, kept pushing on into the evening, regardless of being tired and hot and hungry. I knew exactly why they decided to keep working on the challenge. They chose to push through because they’d found something to care about, and that's always more important than our difficulties and problems. When we focus on what we really care about, we get busy doing something, even in the face of trouble. And that’s how science works.

Lessons from a sea slug

I first learned to care about the natural world around me during my junior year in college. I was in an oceanography course and we were studying sea slugs. (Yes, sea slugs.) A sea slug changed my life. Before then, I’d been, like many people, disengaged and uninterested in science. In third grade, someone came to our classroom and told us we could be the first female astronaut, and I remember thinking, “No, I couldn’t, not me.”

And now? Even though I have a job at NASA, I still feel like I don’t belong in the world of science. I feel more comfortable around athletes and artists than I do with a bunch of Ph.D.s. Maybe it’s some poorly defined stereotype that I’ve somehow bought into or some preconceived notion of how someone who does science is supposed to behave.

But those sea slugs taught me that I cared more about the natural world than I cared about the struggle of not fitting in or the challenge of the work. They appeared so delicate, small and defenseless, and I identified with that. They helped me feel connected. Noticing them forced me to wonder what else I’d start to notice if I slowed down enough to pay attention. And that connection to the natural world helped me stay committed to science, even when it was hard, even when there were problems, even when I felt like running away.

Sure, scientific experimentation, just like much of real life, includes problems, troubles, obstacles and difficulties almost every day. And while it’s true that someone, somewhere has to troubleshoot something every step of the way, we can also be excited about the effort. The OMG team understands that problems and hard work are not the exception, they are the norm. They are part of accomplishment. And it’s totally possible to thrive on these difficulties and challenges.

Look, we could be setting the world on fire right now, not by burning fossil fuels, but by our burning desire to understand our environment. Because the whole point of this experimental mission is to find out how quickly the warmer waters around Greenland are melting the second-largest ice sheet on the planet. It’s major; it’s dire; it’s intense. It’s one of the most important issues of our time.

And sitting there in the back of that plane made me think about how we, as individuals and as a society, have to find something in this world to care about. We have to find something in this world that is more important than our challenges and problems.

And you? I hope you decide to find something to care about. I hope you find something that’s important enough that you’re willing to push through your struggles, your fears and your problems to just do the work.

Find out more about Oceans Melting Greenland.

View and download OMG animations and graphics.

Thank you,

Oceans Melting Greenland is part of NASA Earth Expeditions, a six-month field research campaign to study regions of critical change around the world.



NASA’s modified Gulfstream-III on the runway at Ellington Field Airport in Houston, Texas, with OMG scientists and engineers aboard.

We know more about the moon and other planets than we do some places on our home planet. Remote parts of the world ocean remain uncharted, especially in the polar regions, especially under areas that are seasonally covered with ice and especially near jagged coastlines that are difficult to access by boat. Yet, as global warming forces glaciers in places like Greenland to melt into the ocean, causing increased sea level rise, understanding these remote places has become more and more important.

This past spring, Oceans Melting Greenland (OMG) Principal Investigator Josh Willis led a team of NASA scientists to begin gathering detailed information about the interface between Greenland’s glaciers and the warming ocean waters that surround them. The next step in accessing this extremely remote region involves dropping a series of Airborne Expendable Conductivity Temperature Depth, or AXCTD, probes that will measure ocean temperature and salinity around Greenland, from the sea surface to the sea floor. With this information, they hope to find out how quickly this warmer ocean water is eating away at the ice.

Since no one has ever dropped AXCTDs through a tube at the bottom of a modified Gulfstream-III, the OMG team headed to Ellington Field Airport near NASA’s Johnson Space Center in Houston, Texas, for a test drop into the Gulf of Mexico. I went along for the ride.

"In position!"

Expert NASA T-38 pilot Bill Rieke executes his flight plan to rendezvous with the Oceans Melting Greenland (OMG) scientists and engineers aboard NASA’s modified Gulfstream-III at “drop one.” As soon as photographer James Blair is ready with his high speed and high definition cameras, he calls out “In position!” from the supersonic jet to the team in the G-III over Very High Frequency (VHF) radio. 

The money shot

It’s up to Derek Rutovic, G-III program manager at NASA’s Johnson Space Center, to visually inspect the release of the AXCTD to make sure it does not impact the plane and then to see that the parachute opens. The first test drop was released while the plane was flying at a height of 5,000 feet and a speed of 180-200 knots. 

Temperature and salinity

Alyson Hickey and Derek Rutovic prepare the AXCTD tubes for deployment. After these test flights are complete, the mission heads up to Greenland this fall, where the AXCTDs will measure temperature and salinity around Greenland to make a detailed analysis of how quickly the warmer waters around Greenland are eating away at the ice sheet.

3, 2, 1 ... drop!

G-II pilot Bill Ehrenstrom calls out “Three, two, one, drop!” over the Very High Frequency (VHF) radio channel to signal Rocky Smith, who then pushes the AXCTD tube through a hole in NASA’s modified Gulfstream-III. Rocky then announces, “AXCTD is clear.” 

AXCTD sails down

Oceans Melting Greenland (OMG) Project Manager Steve Dinardo and OMG Principal Investigator Josh Willis wait for a radio signal as the AXCTD sails down through the air to indicate it’s arrived at the sea surface. Once it hits the sea surface, it releases its probe, which travels through the ocean to the sea floor and sends ocean temperature and salinity data up to the team in the aircraft above, who monitor the data in real time. 

The flight path

Both aircraft must execute a complex flight path, which involves filming two precision AXCTD test drops minutes apart.

Details, details, details

To execute the precision flying required to photograph the test drop of a series of AXCTDs, the team is briefed before and after all flights, where every detail is explicitly coordinated. From left: Flight Engineer Alyson Hickey, Oceans Melting Greenland Principal Investigator Josh Willis, photographer James Blair, Oceans Melting Greenland (OMG) Project Manager Steve Dinardo and NASA Gulfstream-III Program Manager Derek Rutovic.

Find out more about Oceans Melting Greenland.

View and download OMG animations and graphics.

Thank you for your comments.


Oceans Melting Greenland is part of NASA Earth Expeditions, a six-month field research campaign to study regions of critical change around the world.



This image was created by Hughes artist Carlos Lopez. It was used in a Surveyor poster, which was a common practice in the days before computer aided drawing.

Surveyor mission planning began in 1960. The mission included seven spacecraft that would soft land on the Moon, using three vernier engines and a retrorocket. The spacecraft would collect data and images of the surface, in order to ensure a safe landing for Apollo astronauts a few years later. Hughes Aircraft Company was selected to design and build the landers and the project was managed by JPL, which also provided tracking and communications. Surveyor I was launched on May 31, 1966, landed on the Moon June 2, and sent back more than 11,000 photos of the lunar surface. The entire image set from Surveyors 1-7 has recently been digitized, and will soon be added to NASA’s Planetary Data System.

This image was created by Hughes artist Carlos Lopez. It was used in a Surveyor poster, which was a common practice in the days before computer aided drawing. This poster was recently received by the JPL Archives, as part of a collection of Surveyor documentation.

For more information about the history of JPL, contact the JPL Archives for assistance. [Archival and other sources: Surveyor Mission Reports, Ranger and Surveyor Fact Sheet, and the NASA Historical Data Book.]


  • Julie Cooper

Haulani Crater in color

Dear Glutdawnous Readers,

The distant dwarf planet that Dawn is circling is full of mystery and yet growing ever more familiar. Ceres, which only last year was hardly more than a fuzzy blob against the stars, is now a richly detailed world, and our portrait grows more elaborate every day. Having greatly surpassed all of its original objectives, the reliable explorer is gathering still more data from its unique vantage point. Everyone who hungers for new knowledge about the cosmos or for bold adventures far from Earth can share in the sumptuous feast Dawn has been serving.

One of the major objectives of the mission was to photograph 80 percent of Ceres' vast landscape with a resolution of 660 feet (200 meters) per pixel. That would provide 150 times the clarity of the powerful Hubble Space Telescope. Dawn has now photographed 99.8 percent with a resolution of 120 feet (35 meters) per pixel.

Dawn captured this picture of Haulani crater in cycle 6 of its third mapping orbit at 915 miles (1,470 kilometers). The crater is shown in a new false-color version above. Its well-defined shape indicates it is relatively young, the impact that formed it having occurred in recent geological times. It displays a substantial amount of bright material, which scientists have identified as some form of salt. The same crater as viewed by Dawn from three times higher altitude is here. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This example of Dawn's extraordinary productivity may appear to be the limit of what it could achieve. After all, the spaceship is orbiting at an altitude of only 240 miles (385 kilometers), closer to the ground than the International Space Station is to Earth, and it will never go lower for more pictures. But it is already doing more.

Since April 11, instead of photographing the scenery directly beneath it, Dawn has been aiming its camera to the left and forward as it orbits and Ceres rotates. By May 25, it will have mapped most of the globe from that angle. Then it will start all over once more, looking instead to the right and forward from May 27 through July 10. The different perspectives on the terrain make stereo views, which scientists can combine to bring out the full three dimensionality of the alien world. Dawn already accomplished this in its third mapping orbit from four times its current altitude, but now that it is seeing the sights from so much lower, the new topographical map will be even more accurate.

Dawn captured this view of Oxo Crater on Jan. 16 from an altitude of 240 miles (385 kilometers). Although it is a modest six miles (10 kilometers) across, it is a particularly interesting crater. This is the only location (so far) on Ceres where Dawn has clearly detected water. Oxo is the second brightest area on Ceres. Only Occator Crater is brighter. Oxo also displays a uniquely large "slump" in its rim, where a mass of material has dropped below the surface. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn is also earning extra credit on its assignment to measure the energy of gamma rays and neutrons. We have discussed before how the gamma ray and neutron detector (GRaND) can reveal the atomic composition down to about a yard (meter) underground, and last month we saw initial findings about the distribution of hydrogen. However, Ceres' nuclear glow is very faint. Scientists already have three times as much GRaND data from this low altitude as they had required, and both spectrometers in the instrument will continue to collect data. In effect, Dawn is achieving a longer exposure, making its nuclear picture of Ceres brighter and sharper.

In December we explained how using the radio signal to track the probe's movements allows scientists to chart the gravity field and thereby learn about the interior of Ceres, revealing regions of higher and lower density. Once again, Dawn performed even better than expected and achieved the mission's planned accuracy in the third mapping orbit. Because the strength of the dwarf planet's gravitational tug depends on the distance, even finer measurements of how it varies from location to location are possible in this final orbit. Thanks to the continued smooth operation of the mission, scientists now have a gravitational map fully twice as accurate as they had anticipated. With additional measurements, they may be able to squeeze out a little more detail, perhaps improving it by another 20 percent before reaching the method's limit.

Dawn took this picture on Feb. 8 at an altitude of 240 miles (385 kilometers). Prominent in the center is part of a crater wall, which shows many scars from subsequent impacts, indicating it is old. Two sizable younger craters with bright material, which is likely some kind of salt, are evident inside the larger crater. Compare the number and size of craters in this scene with those in the younger scene below showing an area of the same size. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn has dramatically overachieved in acquiring spectra at both visible and infrared wavelengths. We have previously delved into how these measurements reveal the minerals on the ground and what some of the interesting discoveries are. Having already acquired more than seven times as many visible spectra and 21 times as many infrared spectra as originally called for, the spacecraft is adding to its riches with additional measurements. We saw in January that VIR has such a narrow view that it will never see all of Ceres from this close, so it is programmed to observe features that have caught scientists' interest based on the broad coverage from higher altitudes.

Dawn took this picture on Feb. 16 (eight days after the picture above) at an altitude of 240 miles (385 kilometers). It shows a region northwest of Occator Crater, site of the famous bright region (which may become one of the most popular tourist destinations on Ceres). (You can locate this area in the upper right of the mosaic shown last month.) Compare the number and size of craters in this scene with those in the older scene above showing an area of the same size. There are fewer craters here, because the material ejected from the impact that excavated Occator resurfaced the area nearby, erasing the craters that had formed earlier. Because Occator is relatively young (perhaps 80 million years old), there has not been enough time for as many new craters to form as in most other areas on Ceres, including the one shown in the previous picture, that have been exposed to pelting from interplanetary debris for much longer. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn's remarkable success at Ceres was not a foregone conclusion. Of course, the flight team has confronted the familiar challenges people encounter every day in the normal routine of piloting an ion-propelled spaceship on a multibillion-mile (multibillion-kilometer) interplanetary journey to orbit and explore two uncharted worlds. But the mission was further complicated by the loss of two of the spacecraft's four reaction wheels, as we have recounted before. (In full disclosure, the devices aren’t actually lost. We know precisely where they are. But given that one stopped functioning in 2010 and the other in 2012, they might as well be elsewhere in the universe; they don’t do Dawn any good.) Without three of these units to control its orientation in space, the robot has relied on its limited supply of hydrazine, which was not intended to serve this function. But the mission's careful stewardship of the precious propellant has continued to exceed even the optimistic predictions, allowing Dawn good prospects for carrying on its fruitful work. In an upcoming Dawn Journal, we will discuss how the last of the dwindling supply of hydrazine may be used for further discoveries.

In the meantime, Dawn is continuing its intensive campaign to reveal the dwarf planet's secrets, and as it does so, it is passing several milestones. The adventurer has now been held in Ceres' tender but firm gravitational embrace longer than it was in orbit around Vesta. (Dawn is the only spacecraft ever to orbit two extraterrestrial destinations, and its mission would have been impossible without ion propulsion.) The spacecraft provided us with about 31,000 pictures of Vesta, and it has now acquired the same number of Ceres.

For an interplanetary traveler, terrestrial days have little meaning. They are merely a memory of how long a faraway planet takes to turn on its axis. Dawn left that planet long ago, and as one of Earth's ambassadors to the cosmos, it is an inhabitant of deep space. But for those who keep track of its progress yet are still tied to Earth, on May 3 the journey will be pi thousand days long. (And for our nerdier friends and selves, it will be shortly after 6:47 p.m. PDT.)

By any measure, Dawn has already accomplished an extraordinary mission, and there is more to look forward to as its ambitious expedition continues.

Dawn is 240 miles (385 kilometers) from Ceres. It is also 3.73 AU (346 million miles, or 558 million kilometers) from Earth, or 1,455 times as far as the moon and 3.70 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take one hour and two minutes to make the round trip.


  • Marc Rayman