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JPL’s First Digital Computer

In January 1953, JPL was in the market for its first digital computer.

After investigating the possibilities, a site visit was made to Consolidated Engineering Corporation (CEC) in Pasadena and the CEC Model 30-203 digital computer, shown in this photo, was eventually selected. The prototype at CEC was given the project number 36-101. JPL and the National Bureau of Standards were the first two customers to order the computer – the one ordered by JPL was 36-102, and the one for NBS was 36-103.

JPL's computer was finally delivered and operational in July 1954. It cost approximately $135,000 (more than $1 million in 2016 dollars). That did not include the operator's console, paper tape input and output, punch card unit, or other related equipment. It featured magnetic drum storage of about 4000 words (a "word" being a number or command) and a word length of 10 decimal digits. It contained more than 1,500 vacuum tubes.

For more information about the history of JPL, contact the JPL Archives for assistance. [Archival and other sources: Section 371 photo albums, Combined Bimonthly Summary No. 33, Datatron Chronology.)

TAGS: JPL'S FIRST DIGITAL COMPUTER, MODEL 30-203, PASADENA, CONSOLIDATED ENGINEERING CORPORTATION (CEC), MAGNETIC DRUM STORAGE

  • Julie Cooper
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Occator Crater

Blue rope lights adorn Dawn mission control at JPL, but not because the flight team is in the holiday spirit (although they are in the holiday spirit).

The felicitous display is more than decorative. The illumination indicates that the interplanetary spacecraft is thrusting with one of its ion engines, which emit a lovely, soft bluish glow in the forbidding depths of space. Dawn is completing another elegant spiral around dwarf planet Ceres, maneuvering to its sixth science orbit.

Dawn’s ion propulsion system has allowed the probe to accomplish a mission unlike any other, orbiting two distant extraterrestrial destinations. Even more than that, Dawn has taken advantage of the exceptional efficiency of its ion engines to fly to orbits at different altitudes and orientations while at Vesta and at Ceres, gaining the best perspectives for its photography and other scientific investigations.

Dawn has thrust for a total of 5.7 years during its deep-space adventure. All that powered flight has imparted a change in the ship’s velocity of 25,000 mph (40,000 kilometers per hour). As we have seen, this is not the spacecraft’s actual speed, but it is a convenient measure of the effect of its propulsive work. Reaching Earth orbit requires only about 17,000 mph (less than 28,000 kilometers per hour). In fact, Dawn’s gentle ion engines have delivered almost 98 percent of the change in speed that its powerful Delta 7925H-9.5 rocket provided. With nine external rocket engines and a core consisting of a first stage, a second stage and a third stage, the Delta boosted Dawn by 25,640 mph (41,260 kilometers per hour) from Cape Canaveral out of Earth orbit and onto its interplanetary trajectory, after which the remarkable ion engines took over. No other spacecraft has accomplished such a large velocity change under its own power. (The previous record holder, Deep Space 1, achieved 9,600 mph, or 15,000 kilometers per hour.)

Early this year, we were highly confident Dawn would conclude its operational lifetime in its fourth orbit at Ceres (and remain there long after). But unexpectedly healthy and with an extension from NASA, Dawn is continuing its ambitious mission. After completing all of its tasks in its fifth scientific phase at Ceres, Dawn is pursuing new objectives by flying to another orbit for still more discoveries. Although we never anticipated adding a row to the table of Dawn’s orbits, last presented in December 2015, we now have an updated version.

Ceres
orbit
Dawn code
name
Dates
(mo.day.yr)
Altitude
in miles
(km)
Resolution
in ft (m)
per pixel
Orbit
period
Equivalent
distance of a soccer ball
1 RC3   04.23.15 – 05.09.15 8,400
(13,600)
4,200
(1,300)
15
days
10 ft
(3.2 m)
2 Survey   06.06.15 –06.30.15 2,700
(4,400)
1,400
(410)
3.1
days
3.4 ft
(1.0 m)
3 HAMO   08.17.15 – 10.23.15 915
(1,470)
450
(140)
19
hours
14 in
(34 cm)
4 LAMO/
XMO1
  12.16.15 – 09.02.16 240
(385)
120
(35)
5.4
hours
3.5 in
(9.0 cm)
5 XMO2   10.16.16 – 11.04.16 920
(1,480)
450
(140)
19
hours
14 in
(35 cm)

As with the obscure Dawn code names for other orbits, this fifth orbit’s name requires some explanation. The extended mission is devoted to undertaking activities not envisioned in the prime mission. That began with two extra months in the fourth mapping orbit performing many new observations, but because it was then the extended mission, that orbit was designated extended mission orbit 1, or XMO1. (It should have been EMO1, of course, but the team’s spellchecker was offline on July 1, the day the extended mission started.) Therefore, the next orbit was XMO2. Dawn left XMO2 on Nov. 4, and we leave it to readers’ imaginations to devise a name for the orbit the spacecraft is now maneuvering to.

Surprisingly, Dawn is flying higher to enhance part of the scientific investigation that motivated going to the lowest orbit. We have explained before that Dawn’s objective in powering its way down to the fourth mapping orbit was to make the most accurate measurements possible of gravity and of nuclear radiation emitted by the dwarf planet.

For more than eight months, the explorer orbited closer to the alien world than the International Space Station is to Earth, and the gamma ray spectra and neutron spectra it acquired are outstanding, significantly exceeding all expectations. But ever-creative scientists have recognized that even with that tremendous wealth of data, Dawn can do still better. Let’s look at this more carefully and consider an example to resolve the paradox of how going higher can yield an improvement.

Ceres
Dawn had this view of Ceres’ limb on Oct. 16 at an altitude of 920 miles (1,480 kilometers). The probe took this picture about 12 minutes after the picture above of Occator Crater. By this time, Dawn’s orbital motion had taken the center of Occator out of the view, but most of the shadowy eastern part is still visible at upper left. A Cerean day lasts about nine hours, so in the time between these two pictures, Ceres rotated as much as Earth would rotate in about 32 minutes. As a result, the change in the sun angle is quite noticeable. You can compare some craters in the two pictures to see how the lighting has changed. This is particularly evident not only in Occator but also in the crater near the center of the large crater visible here (on the lower right of the first picture) as well as the craters below and to the left of it. At the bottom right of this picture is part of the 45-mile (72-kilometer) Kaikara Crater. (Kaikara is a harvest goddess in the kingdom of Bunyoro in Uganda.) You can locate this scene on this map, with Kaikara at 43°N, 222°E and Occator at 20°N, 239°E. Full image (rotated differently and with different picture adjustments) and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The gamma ray and neutron detector (GRaND) reveals some of Ceres’ atomic constituents down to about a yard (meter) underground. The principal limitation in analyzing these spectra is "noise." In fact, noise limits the achievable accuracy of many scientific measurements. It isn’t necessarily the kind of noise that you hear from loud machinery (nor from the mouth of your unhelpful parent, inattentive progeny or boring and verbose coworker), but all natural systems have something similar. Physical processes other than the ones of interest make unwanted contributions to the measurements. The part of a measurement scientists want is called the "signal." The part of a measurement scientists don’t want is called the "noise." The quality of a measurement may be characterized by comparing the strength of the signal to the strength of the noise. (This metric is called the "signal to noise ratio" by people who like to use jargon like "signal to noise ratio.")

We have discussed that cosmic rays, radiation that pervades space, strike atomic nuclei on Ceres, creating the signals that GRaND measures. Remaining at low altitude would have allowed Dawn to enhance its measurement of the Cerean nuclear signal. But scientists determined that an even better way to improve the spectra than to increase the signal is to decrease the noise. GRaND’s noise is a result of cosmic rays impinging directly on the instrument itself and on nearby parts of the spacecraft. With a more thorough measurement of the noise from cosmic rays, scientists will be able to mathematically remove that component of the low altitude measurements, leaving a clearer signal.

For an illustration of all this, suppose you want to hear the words of a song. The words are the signal and the instruments are the noise. (This is a scientific discussion, not a musical one.) It could be that the instruments are so loud and distracting that you can’t make the words out easily.

You might try turning up the volume, because that increases the signal, but it increases the noise as well. If the performance is live, you might even try to position yourself closer to the singer, perhaps making the signal stronger without increasing the noise too much. (Other alternatives are simply to Google the song or ask the singer for a copy of the lyrics, but those methods would ruin this example.)

If you’re doing this in the 21st century (or later), there’s another trick you can employ, taking advantage of computer processing. Suppose you had a recording of the singing with the instruments and then obtained separate recordings of the instruments. You could subtract the musical sounds that constitute the noise, removing the contributions from both guitars, the drums, the harp, both ukuleles, the kazoo and all the theremins. And when you eliminate the noise of the instruments, what remains is the signal of the words, making them much more intelligible.

To obtain a better measure of the noise, Dawn needs to go to higher altitude, where GRaND will no longer detect Ceres. It will make detailed measurements of cosmic ray noise, which scientists then will subtract from their measurements at low altitude, where GRaND observed Ceres signal plus cosmic ray noise. The powerful capability to raise its orbit so much affords Dawn the valuable opportunity to gain greater insight into the atomic composition. Of course, it’s not quite that simple, but essentially this method will help Dawn hear Ceres’ nuclear song more clearly.

Ceres
Dawn took this photo on Oct. 17 at an altitude of 920 miles (1,480 kilometers). Above and to the right of center, part of the wall of a crater has collapsed, allowing material to flow into the larger crater. The area covered by the flow is less densely cratered than the surrounding terrain, because it is younger. We have seen how scientists use the number and size of craters to date geological features (no results are available yet in this area). The larger crater is Ghanan, one of the names of a Mayan maize god, although the devastating flow may not have been good for the maize harvest when the collapse occurred. Ghanan Crater, with an average diameter of 42 miles (68 kilometers), is on this map at 77°N, 31°E. Full image (with different picture adjustments) and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

To travel from one orbit to another, the sophisticated explorer has followed complex spiral routes. We have discussed the nature of these trajectories quite a bit, including how the operations team designs and flies them. But now they are using a slightly different method.

Those of you at Ceres who monitor the ship’s progress probably wouldn’t notice a difference in the type of trajectory. And the rest of you on Earth and elsewhere who keep track through our mission status updates also would not detect anything unusual in the ascent profile (to the extent that a spacecraft using ion propulsion to spiral around a dwarf planet is usual). But celestial navigators are now enjoying their use of a method they whimsically call local maximal energy spiral feedback control.

The details of the new technique are not as important for our discussion here as one of the consequences: Dawn’s next orbit will not be nearly as circular as any of its other orbits at Ceres (or at Vesta). Following the conclusion of this spiral ascent on Dec. 5, navigators will refine their computations of the orbit, and we will describe the details near the end of the month. We will see that as the spacecraft follows its elliptical loops around Ceres, each taking about a week, the altitude will vary smoothly, dipping below 4,700 miles (7,600 kilometers) and going above 5,700 miles (9,200 kilometers). Such a profile meets the mission’s needs, because as long as the craft stays higher than about 4,500 miles (7,200 kilometers), it can make the planned recordings of the cacophonous cosmic rays. We will present other plans for this next phase of the mission as well, including photography, in an upcoming Dawn Journal.

As Dawn continues its work at Ceres, the dwarf planet continues its stately 4.6-year-long orbit around the sun, carrying Earth’s robotic ambassador with it. Ceres follows an elliptical path around the sun (see, for example, this discussion, including the table). In fact, all orbits, including Earth’s, are ellipses. Ceres’ orbit is more elliptical than Earth’s but not as much as some of the other planets. The shape of Ceres’ orbit is between that of Saturn (which is more circular) and Mars (which is more elliptical). (Of course, Ceres’ orbit is larger than Mars’ and smaller than Saturn’s, but here we are describing how much each orbit deviates from a perfect circle.)

When Ceres tenderly took Dawn into its gravitational embrace in March 2015, they were 2.87 AU (267 million miles, or 429 million kilometers) from the sun. In January 2016, we mentioned that Ceres had reached its aphelion, or greatest distance from the sun, at 2.98 AU (277 million miles, or 445 million kilometers). Today at 2.85 AU (265 million miles, or 427 million kilometers), Ceres is closer to the sun than at any time since Dawn arrived, and the heliocentric distance will gradually decrease further throughout the extended mission. (If the number of numbers is overwhelming here, you might reread this paragraph while paying attention to only one set of units, whether you choose AU, miles or kilometers. Ignore the other two scales so you can focus on the relative distances.)

Ceres
Dawn’s location in the solar system is shown on Nov. 7, 2016. On that day, the spacecraft and Ceres were at the same distance from the sun as when Dawn arrived last year. Now as Ceres advances counterclockwise in its elliptical orbit, they will move somewhat closer to the sun. We have plotted Dawn’s progress on this figure before, most recently in September. Image credit: NASA/JPL

Another consequence of orbiting the sun is the progression of seasons. Right on schedule, as we boldly predicted in August 2015, Nov. 13 was the equinox on Ceres, marking the beginning of northern hemisphere autumn and southern hemisphere spring. Although it is celebrated on Ceres with less zeal than on Earth, it is fundamentally the same: the sun was directly over the equator that day, and now it is moving farther south. It takes Ceres so long to orbit the sun that this season will last until Dec. 22, 2017.

A celebration that might occur on Ceres (and which you, loyal Dawnophile, are welcome to attend) would honor Dawn itself. Although the spacecraft completed its ninth terrestrial year of spaceflight in September, on Dec. 12, it will have been two Cerean years since Dawn left Earth for its interplanetary journey. Be sure to attend in order to learn how a dawnniversary is commemorated in that part of the solar system.

Although a year on Ceres lasts much longer than on Earth, 2016 is an unusually long year on our home planet. Not only was a leap day included, but a leap second will be added at the very end of the year to keep celestial navigators’ clocks in sync with nature. The Dawn team already has accounted for the extra second in the intricate plans formulated for the spacecraft. And at that second, on Dec. 31 at 23:59:60, we will be able to look back on 366 days and one second, an especially full and gratifying year in this remarkable deep-space expedition. But we needn’t wait. Even now, as mission control is bathed in a lovely glow, the members of the team as well as space enthusiasts everywhere are aglow with the thrill of new knowledge, the excitement of a daring, noble adventure and the anticipation of more to come.

Dawn is 3,150 miles (5,070 kilometers) from Ceres. It is also 2.08 AU (194 million miles, or 312 million kilometers) from Earth, or 770 times as far as the moon and 2.11 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take 35 minutes to make the round trip.

Dr. Marc D. Rayman
4:00 p.m. PST November 28, 2016

TAGS: DAWN, CERES, ION ENGINE, DWARF PLANET

  • Marc Rayman
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Midwestern United States

Sigh. Sometimes life feels heavy.

Even as the holidays approach and we’re all supposed to be in a holiday spirit, supposed to be joyous. Sometimes we’re just not there.

But, as always, NASA gives me the opportunity to look at Earth from the highest perspective. From above, the world appears remote and untouched. There’s nothing but the timeless, immaculate and infinite beauty of our planet.

Sigh.

Together, you and I get to take this opportunity to share thankfulness for our Earth and everything pristine and beautiful about it.

A creek at Rocky Mountain National Park, Colorado.
I took this photo of a creek at Rocky Mountain National Park, Colorado.

Thank you for reading. I really mean it.

Laura

TAGS: EARTH, HOLIDAYS

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View of the International Space Station orbiting Earth

Slow down and relax. Earth is beautiful.

Earth, from the vantage point of space: Serene, breathtaking, magnificent. No matter how crazy busy your day is, no matter the level of stress, or chaos, or distraction, take a moment today—right now, in fact—to step back and feast on the great wonder of our home planet, Earth.

Soufrière Hills volcano on the Caribbean island of Montserrat.
Soufrière Hills volcano on the Caribbean island of Montserrat.
I like to think about being in nature when I get caught up in the overwhelming day-to-day news cycles. For me, getting out in nature always calms my nerves. It gets me centered and grounded; it reminds me that I have the strength to face life’s challenges.  

The Bering Strait
The Bering Strait, which links the Arctic Ocean with the Bering Sea and separates the continents of Asia and North America at their closest point.
Right now I’m getting ready for a hike in nature. To notice things I normally pass by. To see vistas of faraway mountains and fields of small white flowers in the late fall sunshine.

Rocky Mountain National Park, Colorado.
Rocky Mountain National Park, Colorado.
In those outdoor spaces, you get an experience of timelessness, a reminder of something bigger and longer-lasting than the rapidly shifting beats of the daily grind.

Kangerlussuaq, Greenland.
Kangerlussuaq, Greenland.
So stop and give yourself a break, large or small. Even if it’s just to gaze quietly for a moment at a few of my favorite Earth pix that I gathered here to share with you.

Namaste,
Laura

TAGS: EARTH, OUTDOORS, RELAX

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32nd anniversary of the first rocket motor test

On October 31, 1968 JPL celebrated the 32nd anniversary of the first rocket motor tests in the Arroyo Seco.

The five men in this photo were present at the series of tests that happened in 1936 and 1937, and they came back to JPL for the celebration. From left to right are: William C. Rockefeller, William A. Bollay, Edward S. Forman, Frank J. Malina, and Apollo M.O. Smith. The historical marker found in the JPL Mall was commemorated at this event, and they posed next to a replica of the rocket motor test stand. The photo below shows a print of a 1936 test stand drawing by Frank Malina. He was the Chief Engineer of what would later become JPL, and was Acting Director from 1944 to 1946.

The Bering Strait
A print of a 1936 test stand drawing by Frank Malina.

For more information about the history of JPL, contact the JPL Archives for assistance. [Archival and other sources: various History Collection documents, photo albums, Lab-Oratory.)

TAGS: ROCKET MOTOR TEST, 32ND ANNIVERSARY, ARROYO SECO

  • Julie Cooper
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Dawn photographed this scene in Yalode Crater on June 15, 2016

Dawn has just completed another outstandingly successful observation campaign at Ceres.

Far, far from Earth, the spacecraft has been making measurements at the alien world that were not even imagined until a few months ago. Once again, the experienced explorer has performed its complex assignments with distinction.

When Dawn arrived at Ceres in March 2015, becoming the first spacecraft to reach a dwarf planet, it was looking ahead to a very ambitious year of discovery from four different orbital altitudes. The great benefit of being able to enter orbit rather than fly by is that Dawn can scrutinize its subject over an extended period to develop a detailed, intimate portrait. Taking advantage of the ship’s ability to maneuver with its advanced ion propulsion system, mission planners had carefully selected the four orbits to enable a wide range of measurements.

By February of this year, Dawn had exceeded every one of its original mission objectives and was still going strong, accomplishing many new goals. Nevertheless, no one (at least, no one who was well informed) expected that the probe would complete its new assignments and yet still have the capability to maneuver to a fifth orbit and then undertake even more new observations. But that is exactly what occurred.

After more than eight months orbiting only 240 miles (385 kilometers) above the strange terrain of rock, ice and salt, Dawn ignited one of its ion engines on Sept. 2. By Oct. 6, when it had completed its graceful ascent, Dawn had made 93 spiral loops, reaching an orbit 920 miles (1,480 kilometers) high. From there, revolving once every 18.9 hours, the spacecraft has executed its new program of investigations.

With observations of Ceres from about the same altitude as a year ago in Dawn’s third mapping orbit, scientists will scour the expansive terrain, looking for changes. The most likely change is the presence of new, small craters. Everything in the solar system (including your planetary residence) is subject to strikes from rocks that orbit the sun. Ceres lives in the main asteroid belt between Mars and Jupiter, a particularly rough neighborhood, and being the largest resident there (by far) doesn’t give it any special protection or immunity. In fact, being the largest resident also makes Ceres the largest target.

Ceres
Dawn had this view on June 6, 2016, from an altitude of 240 miles (385 kilometers). The bright material at upper left is on the northwest rim of Kerwan Crater. Geologists have cataloged well over 130 locations on Ceres that are covered with reflective material. (The most famous deposits are in Occator Crater.) The brightness is because briny ice that had been on the surface sublimated, leaving behind salts, which reflect more sunlight than other minerals on the dwarf planet. Extending 174 miles (280 kilometers) across, Kerwan is the largest crater on Ceres. It is centered at 11°S, 124°E on the map shown last month. (Kerwan is a spirit of sprouting maize among the Hopi of Arizona in the US.) Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In addition to remapping Ceres with all of the camera’s color filters, the flight team has given Dawn other tasks. Controlling a sophisticated interplanetary spacecraft conducting complex operations so very far from Earth is never easy (but it’s always incredibly cool). There have been many challenges throughout this ambitious mission, quite unlike any ever undertaken. One of the significant ones was observing specific targets of interest from low altitude. We have explained that orbiting so close to the ground, the spacecraft’s motion was quite difficult to predict with sufficient accuracy far enough in advance to guide the craft so that the instruments’ narrow fields of view would hit specific features. Dawn was designed to map uncharted worlds, not to conduct targeted observations.

The difficulty was compounded by the loss in 2010 and 2012 of two of the four reaction wheels, used for controlling the probe’s orientation. An important side effect of the nudges from the small hydrazine-fueled jets of the reaction control system (even in combination with the two operable reaction wheels in hybrid control mode) was tiny distortions in the spacecraft’s orbital trajectory. The cumulative effect of many jet firings over days and weeks was enough to make it quite challenging to ensure the sensors could spot the targets as Dawn sped around the rapidly rotating orb beneath it.

This is not as difficult at higher altitude both because Dawn does not need to use its jets as often and because the instruments take in a wider area. As a result, the explorer has been better able to catch sight of preselected geological features, and it has acquired valuable new data.

Ceres
Dawn observed this area of craters, hills and canyons inside Urvara Crater on June 2, 2016, from an altitude of 240 miles (385 kilometers). The third largest crater on Ceres, it is 106 miles (170 kilometers) wide. We have seen Urvara several times before, and the crater on the right of this picture is visible in the northwestern part of Urvara shown here and here. Urvara is on the new map at 46°S, 249°E. Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn also has studied selected sites at several times of the Cerean day. Mission planners may determine, for example, that if Dawn points not straight down on a particular orbit at a particular time but rather partially to the side, a certain crater could be spotted soon after Ceres’ nine-hour daily rotation has brought it into sunlight. In other words, it would be early in the morning at the crater when Dawn sees it, providing a nice dawn view. On another orbital revolution, Dawn might point in a different direction to see the same location longer after it has come into sunlight (that is, longer after sunrise), so from that same crater’s point of view, it is later in the day (albeit on a different day).

The spacecraft has done more than look at some special locations at different times of the Cerean day, corresponding to different lighting conditions. In taking pictures for a new map of Ceres this month, everywhere Dawn looked, the illumination was different from the photographs for the maps it compiled in its previous orbits. The orbit now is oriented at a different angle from the sun.

When the interplanetary adventurer was at Vesta, we described the orientation of the orbits in words. Thanks to changes in the Dawn Journal site since then, now we can present a picture showing that the scenery beneath Dawn has been illuminated from a different angle at each orbital altitude. And now in the fifth orbit, by seeing the sights from the same height as in the third mapping orbit but with different lighting, we gain a new perspective on the alien terrain.

Ceres
This illustrates (and simplifies) the relative size and alignment of Dawn’s five science orbits at Ceres. We are looking down on Ceres’ north pole. The spacecraft follows polar orbits, and seen edge-on here, each circular orbit looks like a line. (Orbits 1 and 2 extend off the figure to the right, on the night side. Like 3, 4 and 5, they are centered on Ceres.) The orbits are numbered chronologically. With the sun far to the left, the left side of Ceres is in daylight. Each time the spacecraft travels over the illuminated hemisphere in the different orbital planes, the landscape beneath it is lit from a different angle. Ceres rotates counterclockwise from this perspective (just as Earth does when viewed from the north). So higher numbers correspond to orbits that pass over ground closer to sunrise, earlier in the Cerean day. (Compare this diagram with this figure, which shows only the relative sizes of the orbits, with each one viewed face-on rather than edge-on.) Click on this image for a larger view. Image credit: NASA/JPL

In addition to all of its other work this month, the sophisticated robot has continued some specialized measurements it began at lower altitude. Being higher up does not cause as much of a reduction in the sharpness of some pictures as you might think. Held in a looser gravitational grip, Dawn’s orbital velocity is lower at higher altitude. As a result, observations that require a long exposure are not affected as much by the spacecraft’s movement. That’s helpful for some of the spectra and photographs. For example, Dawn has used its camera to peer into craters near the north and south poles that are in shadow continuously, every Cerean day of the Cerean year. These special locations might trap water molecules that escape from elsewhere on Ceres where it is too warm for them. With the benefits of a wider view from a higher altitude and a more predictable orbital path, Dawn’s coverage this month of these intriguing areas, faintly illuminated by sunlight reflected from crater walls, has been more complete than at lower altitude.

This fifth Ceres campaign was intricate and intensive, but it stayed right on the tight schedule. Dawn began collecting data as planned on Oct. 16 and finished transmitting its findings to Earth on Oct. 29. And it was exceedingly productive, yielding almost 3,000 photographs plus a great many infrared spectra and visible spectra containing a wealth of new information about Ceres.

This week controllers are going to check out the backup camera, as they do twice a year to confirm that it is still healthy and ready to take over should the primary camera develop a problem. Nevertheless, the primary camera remains fully functional. The team also is planning to switch to the backup set of reaction control system thrusters. Dawn has flown for so many years without a full complement of reaction wheels that these hydrazine thrusters have been used far more than anticipated when the ship was designed. They are healthy, but ever-cautious engineers do not want to overuse them.

Achita Crater
Dawn took this photo of Achita Crater on June 3, 2016, from an altitude of 240 miles (385 kilometers). Departing from what may seem to be the theme above of displaying interesting landscapes in the northwestern parts of the largest craters on Ceres, this scene includes most of the 25-mile (40-kilometer) Achita. Although many craters have a mountain peak in the center, this one has an extended ridge. (We have seen other craters on Ceres with central ridges, including Haulani and Urvara here and here.) Also note the bright material at the bottom of the southwest wall and a smaller deposit on the northeast rim. Achita Crater is at 26°N, 66°E on this map. (Achita is a god of agriculture in northern Nigeria.) Full image and caption. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn’s work in this fifth orbit is part of a comprehensive plan for exploring Ceres as thoroughly as possible. Surprising though it may be, we will see next month that scientists have determined that there is even more to learn about Ceres by flying to a higher altitude. So now that Dawn has accomplished all of its objectives for this phase of the mission, it is about to begin another month of maneuvering. On Nov. 4, the spaceship will once again power on ion engine #2 and start another spiral to a sixth orbital observing post.

As Earth and Ceres (accompanied by Dawn) follow their independent orbits around the sun, the distance between them is constantly changing. On Oct. 22, they were at their smallest separation in the 3.5 years from June 2014 to Dec. 2017. On that date, Dawn was a mere 1.900 AU (176.6 million miles, or 284.2 million kilometers) from its first solar system residence. Dawn never loses track of the rest of its team, still stationed on that faraway planet. But after many years of interplanetary travels and more than a year at Vesta, the denizen of deep space is now a devoted companion of Ceres, and that is where it focuses its attention. And it has more work to do as it seeks still greater insights into the nature of its mysterious and exotic home.

Dawn is 920 miles (1,480 kilometers) from Ceres. It is also 1.91 AU (178 million miles, or 286 million kilometers) from Earth, or 705 times as far as the moon and 1.93 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take 32 minutes to make the round trip.

Dr. Marc D. Rayman
2:30 p.m. PDT October 31, 2016

P.S. Now that this Dawn Journal is complete, your correspondent can turn his attention to getting into costume for Halloween. This year, he will be disguised as someone who knew all along that Dawn would engage in a productive and innovative extended mission at Ceres. Just imagine what a great time the trick-or-treaters are going to have when they visit his home!

TAGS: DAWN, CERES, OBSERVATIONS

  • Marc Rayman
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Flying low over Greenland's coastline in NASA's modified G-III aircraft

Science unveils the sheer beauty of Planet Earth

You might expect that being a science writer primarily focused on climate change and climate science could put me in a bad mood. You can see this if you read the comments on many of my blogs, on our NASA Climate Change Facebook page and on my TEDx video. Many commenters think I should express more alarm about our changing climate.

Yes, climate change is happening, it’s real and it’s serious. I know it and my climate scientist friends know it. But I’m just not the kind of person who can spend my days in fear, despair and anger. I just can’t. Fundamentally, it’s not who I am.

What works in my life is finding something positive and then taking action in that positive direction, which explains how I found myself traveling to Kangerlussuaq, Greenland, to support NASA’s Oceans Melting Greenland team in the field. See, NASA is the exploration leader — on this planet and beyond. And believe me, Greenland is out there. It’s so remote, so unknown, so unpopulated, that even after thousands of years of human exploration of our planet and hundreds of years of scientific exploration we still know very little about the ocean surrounding Greenland’s coastline and the water inside its long, ice-carved fjords. Greenland is unusual, a unique environment unto itself. The ice sheet is so vast, it makes its own weather patterns.

Greenland probe drop sites
Oceans Melting Greenland has completed its first survey of the oceans surrounding Greenland using air-deployed temperature and salinity probes. Of the 250 planned measurement locations, 213 probes (blue dots) were dropped, collecting data around the entire island. Credit: Josh Willis/JPL.

So, of course, with NASA’s prominent role in Earth remote sensing and climate change and our capacity to explore the unknown, we’d be the first ones to fly right up into those exceptionally remote fjords to measure the ocean water there. As scientists, decoding the natural world is our way of taking meaningful positive action. It’s our way of caring. We care about the warm water that reaches up Greenland’s icy coastline and melts the ice sheet into the water. We care, so we go there and witness. We go there and we observe. We go there and we measure. And all the while, we feel like we’ve made an effort, we’ve done good work.

And so I flew with Team OMG on a modified NASA G-III aircraft into uncontrolled airspace to places where no other aircraft had flown before, up into those narrow and steep ice-covered fjords, winding in and out, up and down, over and through to observe and measure, like scientists do.

As I was working, I also got to see the brilliant white ice carve its way through steep brown valleys into open ocean water. I saw the glorious expanse of white upon deep blue going on and on and on below us as we flew just 5,000 feet above the winding coastline. It was extraordinary. And this might seem odd to you, but I felt joyous. Yes, I did. Joyous.

For there is something undeniable about the sheer beauty of this planet, and any time you get to experience it is a moment to feel exuberant and alive.

Check out this video of Team OMG celebrating its accomplishments. 

Thanks for reading this blog.

Laura

TAGS: EARTH, CLIMATE CHANGE

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NASA’s G-III about to take off

Swoosh! It’s not a sound so much as a feeling.

You feel it in your ears and through your whole body. And everyone on the plane — two NASA G-III pilots, two flight engineers and the rest of the Oceans Melting Greenland (OMG) crew—feels it at exactly the same time. It has become our inside joke.

The swoosh happens every time the flight engineers drop an Aircraft eXpendable Conductivity Temperature Depth (AXCTD) probe through a hole in the bottom of the plane. The AXCTD comes in a 3-foot-long gray metal tube—with a parachute. After it hits the water, the probe measures ocean temperature and salinity from the sea surface down to about 1,000 meters. The tiny difference between cabin and outside pressure pushes the probe out and makes ears pop at the same time.

This is the second week of our three- to four-week mission that will be repeated every September/October for the next five years. We’re finally starting to iron out all the minor details in our protocol. With so many moving parts, the protocol is important, and the intricate timing helps us make sure no one forgets any details and we get the most accurate record of when and where we drop each one.

Lee and Vaughn 2
The two images above show Flight Engineers Phil Vaughn and Terry Lee ready to drop an AXCTD through a hole in the bottom of the plane.
All of us wear headsets so we can communicate with each other. Here’s an abbreviated version of how it all goes down:

    1. 1. Project Manager Steve Dinardo announces “Data recorder ready.”
    2. 2. Pilots Bill Ehrenstrom and Scott Reagan call out the cloud and ice conditions and the number of minutes to the drop site. Then they determine the altitude for the approach.
    3. Josh Willis
      Lead scientist Josh Willis prepares to mark the probe drop on his GARMIN GPS.
      3. Flight Engineers Terry Lee and Phil Vaughn announce “Tube positioned and ready.”
    4. 4. At 50 seconds from the drop site, the plane slows down and cruises at about 5,000 feet.
    5. 5. At 20 seconds, Lee and Vaughn open the cap of the tube—you know, the one with that hole through the bottom of the plane—and everyone’s ears pop (the first time). Protocol states that they announce “Tube open!” but since our ears just popped, we often hear “Well, of course the tube’s open” or “As you already know—tube’s open.”
    6. 6. At 10 seconds, the pilots count down to 1 and say “drop.” The engineers reply “Sonde’s away” and we all feel that swoosh. There it is. Our ears pop for the second time as the AXCTD is “swooshed” down the tube and out through the hole in the bottom of the plane. (And yes, we all still look at each other with our sly smiles because it’s so much fun to say, “hole in the bottom of the plane.”)
    7. 7. It is the swoosh, more than anything said during the lengthy protocol script playing through my headset, that tells me—OMG lead scientist Josh Willis—to mark the drop on my GARMIN, a GPS we use to record the location of each drop.
    8. 8. After each drop, our aircraft banks steeply and we all silently celebrate the fact that we don’t get motion sickness. We continue circling during the six or so minutes it takes for the science probe to parachute down 5,000 feet to the sea surface and make its way through the water column, sending back data to us in real-time on the plane.

A view of Greenland's southwest coastline
A view of Greenland’s southwest coastline out the window of NASA’s modified G-III aircraft.
We circle until Dinardo says we’re done recording data, then it’s off to the next drop site.

During our many, often challenging hours on the plane together, we share these little inside jokes and laugh—not caring if anyone in the outside world thinks it’s funny. Seems like we are bonding. I couldn’t be happier.

TAGS: FLIGHT ENGINEERS, AIRCRAFT, OCEANS MELTING GREENLAND, G-III PILOTS

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The terminus of Russell Glacier, Greenland.

I went off for a day to visit Russell Glacier, which flows from the Greenland Ice Sheet down the Akuliarusiarsuup Kuua River, into the Kangerlussuaq Fjord and out into the Davis Strait. I knew I'd watch it melt right in front of me. And I expected to feel sad standing there so close to such an obvious and intense signal of global warming and climate change.

I stood there as the Arctic sun moved onto the horizon behind me, breathing the cool air, listening to the loud rush of meltwater passing between me and the 200-foot wall of ice in front of me. I thought about the 100,000-year span of time that this ice sheet has lasted on this planet. I looked toward the Akuliarusiarsuup Kuua River valley thinking about the future of that meltwater as it flowed out to sea. As we continue adding heat-trapping gases to our environment, our climate will keep changing and this meltwater will only increase. Someday the whole ice sheet may be gone.

I was supposed to feel sad. But I didn't. Instead I just felt grateful to be alive, right here, right now, in 2016. To be alive in that time between 100,000 years ago and the whatever-will-happen-in-our-climate-changed future.

I hope you understand.

Laura

TAGS: WALL ICE TRANSITION

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Goldstone Deep Space Instrumentation Facility, Transmitting Station, 1960

JPL photographers don’t take only technical photos, although you’ll find plenty of images of parts, testing, construction, and spacecraft assembly in the JPL Archives photo collection.

On occasion, photographers explore the surrounding area, and take more artistic photos suitable for publicity, brochures, or for display in a JPL building. The newest Historical Photo of the Month shows one example – an early deep space communications antenna in California’s Mojave Desert.

This photo shows the “Transmitting Station” at what was then called the Goldstone Deep Space Instrumentation Facility (also known as the Goldstone Tracking Station or GTS). The 10-kw radio transmitter and 85-foot antenna were installed about two years after the first station ( the “Receiving Station”) became operational in December 1958. It added voice communication and radio command capabilities to the expanding Goldstone operation.

TAGS: GOLDSTONE, DEEP SPACE INSTRUMENT FACILITY, ANTENNA, MOJAVE DESERT, TRANSMITTING STATION, GTS

  • Julie Cooper
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