Thursday, January 29, 2015

iPhone Astrophotography: How to Take Amazing Images of the Sky with Your Smartphone Tonight!

iPhone Astrophotography: How to Take Amazing Images of the Sky with Your Smartphone Tonight!:

All photos credit and copyright: Andrew Symes.


An Iphone portrait of the classical solar system. All photos credit and copyright: Andrew Symes.
Got a smartphone and a telescope?

It’s a sight now common at many star parties. Frequently, you see folks roaming through the darkness, illuminated smartphone aimed skyward. Certainly, the wealth of free planetarium apps has done lots to kindle a renewed interest in the night sky.

Inevitably, after peering through the eyepiece of a telescope, the question then arises:

“Can I get a picture of that with my phone?”

The short answer is yes, with a little skill and patience.

Now simply aiming a camera at the eyepiece of a telescope — known as afocal astrophotography — and shooting without removing the camera lens and physically coupling it to the telescope is a tricky balancing act. Back in the olden days, the Moon and perhaps the brighter planets were the only bright target within bounds of afocal film photographers, and only then after a lengthy set of estimations to hit the correct focal length. The advent of digital cameras and ‘live preview’ means that you can now simply aim, shoot, and throw away or delete anything off center or out of focus. Digital ‘film’ is cheap, and most folks simply use trial and error to get the ‘keepers’. The Moon is an especially bright and easy target for beginners to practice on.

Moon


A gibbous Moon, an easy first pic!
Of course, your typical smartphone, like a webcam, has an imaging chip much smaller than a DSLR. This is why astrophotographers are often tempted to take out a second mortgage (“we don’t really need that second car, do we?” is a common spousal refrain) in pursuit of excellence. Another drawback is that through a smartphone, a planet may look like an overexposed blob. A simple but effective way to get around this is to affix a light reducing filter to the eyepiece. In fact, I’ve used a variable polarizer during live broadcasts of the Virtual Star Party to great effect.  And as with webcam imaging, smartphone astrophotographers now often use automated stacking programs to clean up images and tease out detail. Being an old timer, my faves are still K3CCD Tools and Registax, though many young guns out there now use DeepSkyStacker as well.

Telescope


Andrew Symes’ imaging setup.
Now, I’ll admit, I’m an ‘Android guy,’ and I have put most of my efforts over the years into planetary imaging with a homemade webcam. We therefore sought out in-the-field expertise from someone on the forefront of iPhone astrophotography. Andrew Symes has been taking images of the solar system and beyond with his iPhone coupled to his Celestron NexStar 8” SE telescope for years. He also has one of the few handles on Twitter that we’re envious of, @FailedProtostar. He also ventures out into the chilly nights frequent to his native of Ottawa, Canada to practice his craft, as he observes in temperatures that would drop a Tauntaun.

We caught up with Andrew recently to ask him about some tips of the trade.

Sun


An ‘iPhone Sun’ shot in hydrogen alpha through a Coronado PST.
Universe Today: I know from doing webcam photography that acquiring, centering and focusing are often more than half the battle. Any tips for accomplishing these?

Andrew: Acquiring, centering, and focusing the objects I’m photographing is definitely the big challenge! To speed and simplify the process, I have a dedicated eyepiece that I use in association with my phone and adapter. Before even heading outside, I attach the adapter to this eyepiece, insert my phone, and hold the unit up to a light source to see if the camera lens is properly aligned with the eyepiece. It usually takes a bit of fiddling to get things set properly because if the adapter and eyepiece are not perfectly aligned, nothing will show up on the camera screen. It’s better to get that process out of the way in a lit environment than outside in the dark. I then set that unit aside, and use a separate “adapter-less” zoom eyepiece to locate and center the object in the telescope. Once I’ve acquired the object and am successfully tracking it, I remove my zoom eyepiece and drop in the eyepiece/adapter/phone combo. At that point, the object is usually visible on screen but out of focus since the focus required for the iPhone is different from what works for my eyes! To ensure proper focus, I display the object on my phone’s screen using a live video app called FiLMiC Pro and adjust the focus until it is sharp. I use that app because it has a digital zoom function that lets me get a closer look at the object than the standard iPhone video camera view. Only once I’m confident that I’ve achieved good focus and am tracking the object properly, will I start to record video or shoot individual frames.

A comparison


A comparison of the first image of the Orion Nebula (M42) shot in 1880 (left) with a modern iPhone image.
Universe Today: A question I always like to ask everyone… what was your biggest mistake? Are there any pitfalls to avoid?

Andrew: There are a few pitfalls to avoid when doing iPhone astrophotography. In the past, I would attach the adapter outside while the eyepiece was in the telescope but this caused a number of problems. Often, I would accidentally bump the object out of view while attaching and adjusting the adapter and have to align everything all over again. The weather is also often cold here, and it’s VERY difficult to attach the adapter properly with gloves on, so I would either get really cold hands or spend a lot of unnecessary time fumbling with the adapter with gloved hands. For those reasons, I now prepare the eyepiece/adapter/phone unit indoors in advance as described above. I also now make sure that my iPhone is fully charged before heading outdoors as I’ve found that the iPhone battery drains very quickly when the camera is running constantly — especially in cold weather. Even with an almost-full battery, there are times here in winter when the phone will simply shut down due to the low temperature so I make sure to only start capturing photos/videos once I’m completely confident in my setup.

Lovejoy


Yes, that’s Comet C/2014 Q2 Lovejoy shot with an iPhone!
Universe Today: You’re really pushing the envelope by doing deep sky astro-pics with an iPhone … anything else that you’re experimenting with or working on?

Andrew: My main focus is definitely still on iPhone astrophotography because I like the quick and “light” setup. I don’t need to bring a laptop outside and don’t need equipment that I wouldn’t normally have on me anyway (other than the adapter itself.) So, I want to keep pushing the envelope with what I can capture using the phone and my goal is now is to see how far I can go with deep-sky objects. I’d really like to add the Ring and Dumbbell Nebulae to my portfolio, for example, and see if it’s possible to grab even fainter ones. There are also some non-deep sky targets I’d like to try. I haven’t been successful at capturing a telescopic photo of the ISS, and would love to see if I can catch it transiting the Sun or Moon with my phone. I also still need to capture Uranus and Neptune to round out a solar system collage I put together in 2014!

Lastly, I’m continually experimenting with photo apps to see which are best at capturing and/or processing telescopic images, and have just started using both an iPhone 4S and iPhone 6 to take photos and video. Surprisingly, I still prefer the 4S for planetary imaging as I haven’t been able to properly capture the true colors of planets with the iPhone 6 yet. The 6 has better camera resolution but seems to be adjusting the exposure of small, faint objects like planets differently than the 4S, so I need to change my routine and techniques to compensate. The methods I’ve become accustomed to using with the 4S don’t seem to translate directly to the 6 so I have some learning yet to do!

M13


An iPhone capture of Messier 13.
Amazing stuff, for sure. And to think, we were all gas-hypering film and using absurdly long focal lengths to get blurry planetary images just a few decades ago!

-Check out more of Andrew’s images, as well as read more about how he does it.

-Got a pic, shot with a smartphone or otherwise? Send ‘em in to Universe Today!



About 

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

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How Are Planets Formed?

How Are Planets Formed?:

This artist's conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave


This artist’s conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave
How did the Solar System’s planets come to be? The leading theory is something known as the “protoplanet hypothesis”, which essentially says that very small objects stuck to each other and grew bigger and bigger — big enough to even form the gas giants, such as Jupiter.

But how the heck did that happen? More details below.

Birthing the Sun

About 4.6 billion years ago, as the theory goes, the location of today’s Solar System was nothing more than a loose collection of gas and dust — what we call a nebula. (Orion’s Nebula is one of the most famous examples you can see in the night sky.)

Astrophoto: The Orion Nebula by Vasco Soeiro


The Orion Nebula. Image Credit: Vasco Soeiro
Then something happened that triggered a pressure change in the center of the cloud, scientists say. Perhaps it was a supernova exploding nearby, or a passing star changing the gravity. Whatever the change, however, the cloud collapsed and created a disc of material, according to NASA.

The center of this disc saw a great increase in pressure that eventually was so powerful that hydrogen atoms loosely floating in the cloud began to come into contact. Eventually, they fused and produced helium, kickstarting the formation of the Sun.

The Sun was a hungry youngster — it ate up 99% of what was swirling around, NASA says — but this still left 1% of the disc available for other things. And this is where planet formation began.

These images are some of the first to be taken during Spitzer's warm mission -- a new phase that began after the telescope, which operated for more than five-and-a-half years, ran out of liquid coolant. They show a star formation region (DR22 in Cygnus),DR22, in the constellation Cygnus the Swan. Credit: NASA / JPL-Caltech


These images are some of the first to be taken during Spitzer’s warm mission — a new phase that began after the telescope, which operated for more than five-and-a-half years, ran out of liquid coolant. They show a star formation region (DR22 in Cygnus),DR22, in the constellation Cygnus the Swan. Credit: NASA / JPL-Caltech
Time of chaos

The Solar System was a really messy place at this time, with gas and dust and debris floating around. But planet formation appears to have happened relatively rapidly. Small bits of dust and gas began to clump together. The young Sun pushed much of the gas out to the outer Solar System and its heat evaporated any ice that was nearby.

Over time, this left rockier planets closer to the Sun and gas giants that were further away. But about four billion or so years ago, an event called the “late heavy bombardment” resulted in small bodies pelting the bigger members of the Solar System. We almost lost the Earth when a Mars-sized object crashed into it, as the theory goes.

What caused this is still under investigation, but some scientists believe it was because the gas giants were moving around and perturbing smaller bodies at the fringe of the Solar System. At any rate, in simple terms, the clumping together of protoplanets (planets in formation) eventually formed the planets.

Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone


Artist’s impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone
We can still see leftovers of this process everywhere in the Solar System. There is an asteroid belt between Mars and Jupiter that perhaps would have coalesced into a planet had Jupiter’s gravity not been so strong. And we also have comets and asteroids that are sometimes considered referred to as “building blocks” of our Solar System.

We’ve described in detail what happened in our own Solar System, but the important takeaway is that many of these processes are at work in other places. So when we speak about exoplanet systems — planets beyond our Solar System — it is believed that a similar sequence of events took place. But how similar is still being learned.

Making the case

One major challenge to this theory, of course, is no one (that we know of!) was recording the early history of the Solar System. That’s because the Earth wasn’t even formed yet, so it was impossible for any life — let alone intelligent life — to keep track of what was happening to the planets around us.

Artist's impression of the Solar Nebula. Image credit: NASA


Artist’s impression of the Solar Nebula. Image credit: NASA
There are two major ways astronomers get around this problem. The first is simple observation. Using powerful telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers can actually observe dusty discs around young planets. So we have numerous examples of stars with planets being born around them.

The second is using modelling. To test their observational hypotheses, astronomers run computer modelling to see if (mathematically speaking) the ideas work out. Often they will try to use different conditions during the simulation, such as perhaps a passing star triggering changes in the dust cloud. If the model holds after many runs and under several conditions, it’s more likely to be true.

That said, there still are some complications. We can’t use modelling yet to exactly predict how the planets of the Solar System ended up where they were. Also, in fine detail our Solar System is kind of a messy place, with phenomena such as asteroids with moons.

This animation, created from individual radar images, clearly show the rough outline of 2004 BL86 and its newly-discovered moon. Credit: NASA/JPL-Caltech


This animation, created from individual radar images, clearly show the rough outline of 2004 BL86 and its newly-discovered moon. Credit: NASA/JPL-Caltech
And we need to have a better understanding of external factors that could affect planet formation, such as supernovae (explosions of old, massive stars.) But the protoplanet hypothesis is the best we’ve got — at least for now.

We have written many articles about the protoplanet hypothesis for Universe Today. Here’s an article about how the Solar System was formed, and here’s an article about protoplanets. We’ve also recorded a series of episodes of Astronomy Cast about every planet in the Solar System. Start here, Episode 49: Mercury.



About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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What it Would Look Like if the Sun was Replaced with Other Stars?

What it Would Look Like if the Sun was Replaced with Other Stars?:



How would our horizon look if Earth orbited around another star, such as Alfa-Centauri, Sirius, or Polaris? Roscosmos TV has released two new videos that replace our familiar Sun and Moon with other stars and planets. While these are completely fantastical — as Earth would have evolved very differently or not evolved at all in orbit around a giant or binary star — the videos are very well done and they give a new appreciation for the accustomed and comforting views we have. The Sun video is above; the Moon below:


How our horizon might look if Earth orbited the star Artcurus. Credit: TV Roskosmos.


How our horizon might look if Earth orbited the star Artcurus. Credit: TV Roskosmos.


Check out Roscosmos TV You Tube page — they have a great collection of videos, from launches to science to fantastical videos like the ones we featured here.

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Found: Mars Orbiter Locates Beagle 2 Lander

Found: Mars Orbiter Locates Beagle 2 Lander:





The Beagle 2 Lander, built by the United Kingdom, has been thought lost on Mars since Dec. 25, 2003, but has now been found in images from NASA's Mars Reconnaissance Orbiter.





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Asteroid 2004 BL86 Has a Small Moon

Asteroid 2004 BL86 Has a Small Moon:





This movie of asteroid 2004 BL86 was generated from data collected by NASA's Deep Space Network antenna at Goldstone, California, on Jan. 26, 2015. Twenty individual images were used.





Original enclosures:
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Technical Origami

Technical Origami:





How do you develop the largest spinning antenna ever used on a NASA satellite? Testing, testing. . . .





Asteroid That Flew Past Earth Has Moon

Asteroid That Flew Past Earth Has Moon:


This GIF shows asteroid 2004 BL86, which safely flew past Earth on Jan. 26, 2015.



Radar Images from Goldstone indicate that asteroid 2004 BL86, which safely flew past Earth, has a moon.






NASA's Dawn Spacecraft Captures Best-Ever View of Dwarf Planet

NASA's Dawn Spacecraft Captures Best-Ever View of Dwarf Planet:


Ceres Sharper Than Ever (Animation)



NASA's Dawn spacecraft has returned the sharpest images ever seen of the dwarf planet Ceres.






Citizen Scientists Lead Astronomers to Mystery Objects in Space

Citizen Scientists Lead Astronomers to Mystery Objects in Space:


Finding 'Yellowballs' in our Milky Way



"Hmm, what's that?" Simply by asking the question, volunteers have led researchers to illuminate a little-known stage of massive star formation.






Cassini Catches Titan Naked in the Solar Wind

Cassini Catches Titan Naked in the Solar Wind:


Titan Observed Naked in the Solar Wind




Researchers studying data from NASA's Cassini mission have observed that Saturn's largest moon, Titan, behaves much like Venus, Mars or a comet when exposed to the raw power of the solar wind.






Sunday, January 25, 2015

Star Wars: Modern Lightsaber Battle

Star Wars: Modern Lightsaber Battle:


Original enclosures:
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CATS Out of The Bag, Crawling Around ISS for Science Down Below

CATS Out of The Bag, Crawling Around ISS for Science Down Below:

This video frame shows a robotic arm on the space station, called the Japanese Experiment Module Remote Manipulator System, successfully installing NASA's Cloud-Aerosol Transport System (CATS) to the Space Station’s Japanese Experiment Module on Jan. 22, 2015. Credit: NASA


The Japanese robotic arm installs the CATS experiment on an external platform on Japan’s Kibo lab module. The SpaceX Dragon commercial cargo craft is seen at the right center of the image. Credit: NASA TV
See way cool installation video below
“Robotic controllers let the CATS out of the bag!” So says NASA spokesman Dan Huot in a cool new NASA timelapse video showing in detail how CATS crawled around the space stations gangly exterior and clawed its way into its new home – topped off with a breathtaking view of our home planet that will deliver science benefits to us down below.

The CATS experiment was installed on the exterior of the International Space Station (ISS) via a first ever type of robotic handoff, whereby one of the stations robotic arms handed the rectangular shaped instrument off to a second robotic arm. Sort of like relays runners passing the baton while racing around the track for the gold medal.

In this case it was all in the name of science. CATS is short for Cloud Aerosol Transport System.

Ground controllers at NASA’s Johnson Space Center in Houston plucked CATS out of the truck of the recently arrived SpaceX Dragon cargo delivery vehicle with the Special Purpose Dexterous Manipulator (Dextre). Then they passed it off to a Japanese team of controllers at JAXA, manipulating the second arm known as the Japanese Experiment Module Remote Manipulator System. The JAXA team then installed CATS onto an external platform on Japans Kibo laboratory.

CATS is a new Earth Science instrument dedicated to collecting continuous data about clouds, volcanic ash plumes and tiny airborne particles that can help improve our understanding of aerosol and cloud interactions and improve the accuracy of climate change models.

The remote-sensing laser instrument measures clouds and the location and distribution of pollution, dust, smoke, and other particulates and aerosols in the atmosphere that directly impacts the global climate.

Data from CATS will be used to derive properties of cloud/aerosol layers at three wavelengths: 355, 532, 1064 nm.

Check out this cool NASA ‘Space to Ground’ video showing CATS installation



Video caption: NASA’s Space to Ground on 1/23/15 covers CATS Out of The Bag. This is your weekly update on what’s happening aboard the International Space Station. Got a question or comment? Use #spacetoground to talk to us.

All the movements were conducted overnight by robotic flight controllers on the ground. They installed CATS to an external platform on Japan’s Kibo lab module.

CATS is helping to open a new era on the space station research dedicated to expanding its use as a science platform for making extremely valuable remote sensing observations for Earth Science.

The CATS instrument is the fourth successful NASA Earth science launch out of five scheduled during a 12-month period. And it is the second to be installed on the exterior of the ISS, following ISS-RapidScat that was brought by the SpaceX CRS-4 Dragon.

The fifth launch — the Soil Moisture Active Passive satellite — is scheduled for Jan. 29 from Vandenberg Air Force Base in California.

CATS was launched to the station as part of the payload aboard the SpaceX Dragon CRS-5 cargo vessel bolted atop the SpaceX Falcon 9 for the spectacular nighttime blastoff on Jan. 10 at 4:47 a.m. EST from Cape Canaveral Air Force Station in Florida.

CATS was loaded in the unpressurized rear trunk section of Dragon.

Kibo Laboratory The new CATS experiment delivered by the SpaceX commercial cargo craft will be installed on a platform outside Japan’s Kibo Laboratory module. Credit: NASA


Kibo Laboratory
The new CATS experiment delivered by the SpaceX commercial cargo craft will be installed on a platform outside Japan’s Kibo Laboratory module. Credit: NASA
The Dragon CRS-5 spacecraft was loaded with over 5108 pounds (2317 kg) of scientific experiments, technology demonstrations, the CATS science payload, student research investigations, crew supplies, spare parts, food, water, clothing and assorted research gear for the six person crew serving aboard the ISS.

It successfully rendezvoused at the station on Jan. 12 after a two day orbital chase, delivering the critical cargo required to keep the station stocked and humming with science.

Artist concept of CATS on ISS. Credit: NASA


Artist concept of CATS on ISS. Credit: NASA
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer



About 

Dr. Ken Kremer is a speaker, research scientist, freelance science journalist (Princeton, NJ) and photographer whose articles, space exploration images and Mars mosaics have appeared in magazines, books, websites and calendars including Astronomy Picture of the Day, NBC, BBC, SPACE.com, Spaceflight Now and the covers of Aviation Week & Space Technology, Spaceflight and the Explorers Club magazines. Ken has presented at numerous educational institutions, civic & religious organizations, museums and astronomy clubs. Ken has reported first hand from the Kennedy Space Center, Cape Canaveral, NASA Wallops, NASA Michoud/Stennis/Langley and on over 40 launches including 8 shuttle launches. He lectures on both Human and Robotic spaceflight - www.kenkremer.com. Follow Ken on Facebook and Twitter

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Across The Universe Journal| October 31

Across The Universe Journal | October 31:



ion engine

Dear Dawnomalies,

Farther from Earth and from the sun than it has ever been, Dawn is on course and on schedule for its March 2015 arrival at Ceres, an enigmatic world of rock and ice. To slip gracefully into orbit around the dwarf planet, the spacecraft has been using its uniquely capable ion propulsion system to reshape its heliocentric orbit so that it matches Ceres’ orbit. Since departing the giant protoplanet Vesta in Sep. 2012, the stalwart ship has accomplished 99.46 percent of the planned ion thrusting.

What matters most for this daring mission is its ambitious exploration of two uncharted worlds (previews  of the Ceres plan were presented from December 2013 to August 2014), but this month and next, we will consider that 0.54 percent of the thrusting Dawn did not accomplish. We begin by seeing what happened on the spacecraft and in mission control. In November we will describe the implications for the approach phase of the mission. (To skip now to some highlights of the new approach schedule, click on the word “click.”)


The story begins with radiation, which fills space. Earth’s magnetic field deflects much of it, and the atmosphere absorbs much of the rest, but there is no such protection for interplanetary spacecraft. Some particles were energized as recently as a few days earlier on the sun or uncounted millennia ago at a supernova far away in the Milky Way galaxy. Regardless of when and where it started, one particle’s cosmic journey ended on Sep. 11 at 2:27 a.m. PDT inside Earth’s robotic ambassador to the main asteroid belt. The particle penetrated one of the spacecraft panels and struck an electrical component in a unit that controls the ion propulsion system.



ion engine


Photo of ion engine thrusting in a vacuum chamber at JPL. This thrust test was on Deep Space 1, which paved the way for Dawn. Credit: NASA/JPL
At the time the burst of radiation arrived, Dawn was thrusting as usual, emitting a blue-green beam of high velocity xenon ions from engine #1. Ten times as efficient as conventional chemical propulsion, ion propulsion truly enables this unique mission to orbit two extraterrestrial destinations. With its remarkably gentle thrust, it uses xenon propellant so frugally that it takes more than three and a half days to expend just one pound (0.45 kilograms), providing acceleration with patience.

Dawn’s electronics were designed to be resistant to radiation. On this occasion, however, the particle managed to deposit its energy in such a way that it disrupted the behavior of a circuit. The control unit used that circuit to move valves in the elaborate system that transports xenon from the main tank at a pressure of 500 psi (34 times atmospheric pressure) to the ion engine, where it is regulated to around two millionths of a psi (ten million times lower than atmospheric pressure), yielding the parsimonious expenditure of propellant. The controller continued monitoring the xenon flow (along with myriad other parameters needed for the operation of the ion engine), but the valves were unable to move in response to its instructions. Thrusting continued normally for more than an hour as the xenon pressure in the engine decreased very gradually. (Everything with ion propulsion is gradual!) When it reached the minimum acceptable value, the controller executed an orderly termination of thrust and reported its status to the main spacecraft computer.

When the computer was informed that thrust had stopped, it invoked one of Dawn’s safe modes. It halted other activities, reconfigured some of the subsystems and rotated to point the main antenna to Earth.

The events to that point were virtually identical to a radiation strike that occurred more than three years earlier. Subsequent events, however, unfolded differently.

In normal circumstances, the mission control team would be able to guide the spacecraft back to normal operations in a matter of hours, as they did in 2011. Indeed, the longest part of the entire process then was simply the time between when Dawn turned to Earth and when the next scheduled tracking session with NASA’s worldwide Deep Space Network (DSN) began. Most of the time, Dawn operates on its own using instructions stored in its computer by mission controllers. The DSN is scheduled to communicate with it only at certain times.

Dawn performs a carefully choreographed 2.5-year pas de trois from Vesta to Ceres. Celestial navigators had long known that the trajectory was particularly sensitive to glitches that interfere with ion thrusting during part of 2014. To ensure a prompt response to any interruptions in thrust, therefore, the Dawn project collaborated with the DSN to devise a new method of checking in on the spacecraft more frequently (but for short periods) to verify its health. This strategy helped them detect the condition soon after it occurred.



Dawn from Vesta to Ceres


Artist’s concept of Dawn traveling from the giant protoplanet Vesta (in a Dawn photo at lower right) to dwarf planet Ceres (upper left). Credit: NASA/JPL
When an antenna at the DSN complex near Madrid, Spain, received the explorer’s radio signal that morning, it was apparent that Dawn was neither in exactly the configuration to be expected if it were thrusting nor if it had entered one of its safe modes. Although they did not establish until later in the day what was happening, it turns out that not one but two anomalies occurred on the distant spacecraft, likely both triggered by particles in the radiation burst. Dawn encountered difficulty controlling its attitude with its usual exquisite precision. (Engineers use “attitude” to refer to the orientation of the craft in the zero-gravity conditions of spaceflight. In this case, the spacecraft’s orientation was not controlled with its usual precision, but the spacecraft’s outlook was as positive and its demeanor as pleasant as ever.) Instead of maintaining a tight lock of its main antenna on faraway Earth, it was drifting very slightly. The rate was 10 times slower than the hour hand on a clock, but that was enough to affect the interplanetary communication. Ultimately one of the onboard systems designed to monitor the overall health and performance of all subsystems detected the attitude discrepancy and called for another, deeper safe mode.

In this safe mode, Dawn further reconfigured some of the subsystems and used a different part of the attitude control system to aim at the solar system’s most salient landmark: the sun. It switched to one of its auxiliary antennas and transmitted a wide radio beam.

Meanwhile, the operations team began working with the DSN and other missions to arrange for more time to communicate with Dawn than had previously been scheduled. Projects often collaborate this way, making adjustments for each other in the spirit of shared interest in exploring the solar system with the limited number of DSN stations. Later in the day on Thursday, when an antenna near Goldstone, Calif., was made available to point at Dawn, it was stable in safe mode.

The team decided to aim for resuming thrusting on Monday, Sep. 15. They had already formulated a detailed four-week sequence of commands to transmit to the spacecraft then, so this would avoid the significant complexity of changing the timing, a process that in itself can be time-consuming. This plan would limit the duration of the missed thrust during this sensitive portion of the long flight from Vesta to Ceres. Time was precious.

While it was in safe mode, there were several major challenges in investigating why the spacecraft had not been able to point accurately. The weak radio signal from the auxiliary antenna allowed it to send only a trickle of data. Readers who have heard tales of life late in the 20th century can only imagine what it must have been like for our ancestors with their primitive connections to the Internet. Now imagine the Dawn team trying to diagnose a very subtle drift in attitude that had occurred on a spacecraft 3.2 AU (almost 300 million miles, or 480 million kilometers) from Earth with a connection about one thousand times slower than a dial-up modem from 20 years ago. In addition, radio signals (which all regular readers know travel at the universal limit of the speed of light) took 53 minutes to make the round trip. Therefore, every instruction transmitted from JPL required a long wait for a response. Combined with the intermittent DSN schedule, these conditions greatly limited the pace at which operations could proceed.

To improve the efficiency of the recovery, the DSN agreed to use its newest antenna, known as Deep Space Station 35 (DSS-35), near Canberra, Australia. DSS-35 was not quite ready yet for full-time operational use, and the DSN postponed some of the planned work on it to give Dawn some very valuable extra communications opportunities. It’s impressive how all elements of NASA work together to make each project successful.



DSN with cranes


Deep Space Station 35 near Canberra, Australia. This antenna, still undergoing final preparations before beginning regular operational support of interplanetary missions, is 112 feet (34 meters) in diameter. Credit: CDSCC/NASA
Engineers hypothesized that the reconfigurations upon entering safe mode might have rectified the anomaly that prevented the spacecraft from maintaining its characteristic stability. While some people continued the previously planned work of finalizing preparations for Ceres, most of the rest of the operations team split into two shifts. That way, they could progress more quickly through the many steps necessary to command the spacecraft out of safe mode to point the main antenna to Earth again so they could download the large volume of detailed data it had stored on what had occurred. By the time they were ready late on Friday night, however, there was a clear indication that the spacecraft was not ready. Telemetry revealed that the part of the attitude control software that was not used when pointing at the sun in safe mode — but that would be engaged when pointing elsewhere — was still not operating correctly.

Experts at JPL, along with a colleague at Orbital Sciences Corporation in Dulles, VA, scrutinized what telemetry they could receive, performed tests with the spacecraft simulator, and conducted other investigations. The team devised possible explanations, and one by one they tested and eliminated them. Their intensive efforts were powered not only by their skill and their collective experience on Dawn and other missions but also by plenty of pizza and fancy cupcakes. (The cupcakes were delivered in a box lovingly decorated with a big heart, ostensibly by the young daughter of the team member who provided them, but this writer suspects it might have been the team member himself. Regardless, embedded in the action, your correspondent established that the cupcakes were not only a yummy dessert after a pizza lunch but also that they made a terrific dinner. What a versatile and delectable comestible!)

Despite having all the expertise and creativity that could be brought to bear, by Saturday afternoon nothing they had tried had proven effective, including restarting the part of the software that seemed to be implicated in the pointing misbehavior. Confronting such an unyielding situation was not typical for such an experienced flight team. Whenever Dawn had entered one of its safe modes in the preceding seven years of flight, they had usually established the cause within a very few hours and knew precisely how to return to normal operations quickly. This time was different.

The team had still more ideas for systematically trying to fix the uncooperative pointing, but with the clock ticking, the mission director/chief engineer, with a conviction that can only come from cupcakes, decided to pursue a more dramatic course. It would put the spacecraft into an even deeper safe mode, and hence would guarantee a longer time to restore it to its normal operational configuration, but it also seemed a more likely solution. It thus appeared to offer the best possibility of being ready to start thrusting on schedule on Monday, avoiding the difficulty of modifying the four-week sequence of commands and minimizing the period of lost thrust. The idea sounds simple: reboot the main computer.

Rebooting the computer on a ship in deep space is a little bigger deal than rebooting your laptop. Indeed, the last time controllers commanded Dawn to restart its computer was in April 2011, when they installed a new version of software. Such a procedure is very delicate and is not undertaken lightly, given that the computer controls all of the robot’s functions in the unforgiving depths of space. Nevertheless, the team made all the preparations that afternoon and evening, and the computer rebooted as commanded two minutes after midnight.



Thrusting with Engine 1


Dawn thrusting with ion engine #1, which was in use when the radiation strike occurred. Credit: NASA/JPL


Thrusting with Engine #2


Dawn thrusting with ion engine #2, which controllers switched to at the end of the recovery operations. The spacecraft rotates to aim the active ion engine in the required direction while keeping the solar arrays pointed at the sun. Credit: NASA/JPL


Thrusting with engine 3


Dawn thrusting with ion engine #3. This illustrates how the spacecraft would be oriented if it were using that engine instead of #1 or #2. Credit: NASA/JPL
Engineers immediately set about the intricate tasks of verifying that the probe correctly reloaded all of its complex software and was still healthy. It took another 12 hours of reconfiguring the spacecraft and watching the driblet of data before they could confirm around noon on Sunday that the attitude control software was back to its usual excellent performance. Whatever had afflicted it since the radiation burst was now cured. After a brief pause for the tired team members on shift in Dawn mission control to shout things like “Yes!” “Hurray!” and “Time for more cupcakes!” they continued with the complex commanding to point the main antenna to Earth, read out the diagnostic logs, and return each subsystem to its intended state. By Monday afternoon, they had confirmed that hundreds upon hundreds of measurements from the spacecraft were exactly what they needed to be. Dawn was ready to resume ion thrusting, heading for an exciting, extended exploration of the first dwarf planet discovered.

Throughout the contingency operations, even as some people on the team delved into diagnosing and recovering the spacecraft and others continued preparing for Ceres, still others investigated how the few days of unplanned coasting would affect the trajectory. For a mission using ion propulsion, thrusting at any time is affected by thrusting at all other times, in both the past and the future. The new thrust profiles (specifically, both the throttle level and the direction to point the ion engine every second) for the remainder of the cruise phase and the approach phase (concluding with entering the first observation orbit, known as RC3) would have to compensate for the coasting that occurred when thrusting had been scheduled. The flight plans are very complicated, and developing them requires experts who apply very sophisticated software and a touch of artistry. As soon as the interruption in thrust was detected on Thursday, the team began formulating new designs. Initially most of the work assumed thrusting would start on Monday. After the first few attempts to correct the attitude anomaly were unsuccessful, however, they began looking more carefully into later dates. Thanks to the tremendous flexibility of ion propulsion, there was never doubt about ultimately getting into orbit around Ceres, but the thrust profiles and the nature and timeline of the approach phase could change quite a bit.

Once controllers observed that the reboot had resolved the problem, they put the finishing touches on the Monday plan. The team combined the new thrust profile with the pre-existing four-week set of commands already scheduled to be radioed to the spacecraft during a DSN session on Monday. They had already made another change as well. When the radiation burst struck the probe, it had been using ion engine #1, ion engine controller #1, and power unit #1. Although they were confident that simply turning the controller off and then on again would clear the glitch, just as it had in 2011 (and as detailed analysis of the electrical circuitry had indicated), they had decided a few days earlier that there likely would not be time to verify it, so prudence dictated that near-term thrusting not rely on it. Therefore, following the same strategy used three years earlier, the new thrust profile was based on controller #2, which meant it needed to use ion engine #2 and power unit #2. (For those of you keeping score, engine #3 can work with either controller and either power unit, but the standard combination so far has been to use the #1 devices with engine #3.) Each engine, controller, and power unit has been used extensively in the mission, and the expedition now could be completed with only one of each component if need be.

By the time Dawn was once again perched atop its blue-green pillar of xenon ions on Monday, it had missed about 95 hours of thrusting. That has surprising and interesting consequences for the approach to Ceres early next year, and it provides a fascinating illustration of the creativity of trajectory designers and the powerful capability of ion propulsion. Given how long this log is already, however, we will present the details of the new approach phase next month and explain then how it differs from what we described last December. For those readers whose 2015 social calendars are already filling up, however, we summarize here some of the highlights.

Throughout this year, the flight team has made incremental improvements in the thrust plan, and gradually the Ceres arrival date has shifted earlier by several weeks from what had been anticipated a year ago. Today Dawn is on course for easing into Ceres’ gravitational embrace on March 6. The principal effect of the missed thrust is to make the initial orbit larger, so the spaceship will need more time to gently adjust its orbit to RC3 at 8,400 miles (13,500 kilometers). It will reach that altitude on about April 22 which, as it turns out, differs by less than a week from the schedule last year.



Hubble images of Ceres


Four views of Ceres as it rotates, as seen with Hubble Space Telescope, are the best we have. The brightest feature has been exaggerated here. Dawn’s pictures by the end of January will be better than these, and the view will continue to improve after that. Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park)
During the approach phase, the spacecraft will interrupt thrusting occasionally to take pictures of Ceres against the background stars, principally to aid in navigating the ship to the uncharted shore ahead. Because arrival has advanced from what we presented 10 months ago, the schedule for imaging has advanced as well. The first “optical navigation” photos will be taken on about Jan. 13. (As we will see next month, Dawn will glimpse Ceres once even sooner than that, but not for navigation purposes.) The onboard camera, designed for mapping Vesta and Ceres from orbit, will show a fuzzy orb about 25 pixels across. Although the pictures will not yet display details quite as fine as those already discerned by Hubble Space Telescope, the different perspective will be intriguing and may contain surprises. The pictures from the second approach imaging session on Jan. 26 will be slightly better than Hubble’s, and when the third set is acquired on Feb. 4, they should be about twice as good as what we have today. By the time of the second “rotation characterization” on about Feb. 20 (nearly a month earlier than was planned last year), the pictures will be seven times better than Hubble’s.

While the primary purpose of the approach photos is to help guide Dawn to its orbital destination, the images (and visible and infrared spectra collected simultaneously) will serve other purposes. They will provide some early characterizations of the alien world so engineers and scientists can finalize sensor parameters to be used for the many RC3 observations. They will also be used to search for moons. And the pictures surely will thrill everyone along for the ride (including you, loyal reader), as a mysterious fuzzy patch of light, observed from afar for more than two centuries and once called a planet, then an asteroid and now a dwarf planet, finally comes into sharper focus. Wonderfully exciting though they will be, the views will tantalize us, whetting our appetites for more. They will draw us onward with their promises of still more discoveries ahead, as this bold adventure into the unknown begins to reveal the treasures we have so long sought.

Dawn is 1.2 million miles (1.9 million kilometers) from Ceres. It is also 3.65 AU (339 million miles, or 546 million kilometers) from Earth, or 1,475 times as far as the moon and 3.67 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take one hour and one minute to make the round trip.

Dr. Marc D. Rayman

5:00 p.m. PDT October 31, 2014
P.S. While Dawn thrusts tirelessly, your correspondent is taking the evening off for Halloween. No longer able to fit in his costume from last year (and that has nothing to do with how many cupcakes he has consumed), this year he is expanding his disguise. Expressing the playful spirit of the holiday, he will be made up as a combination of one part baryonic matter and four parts nonbaryonic cold dark matter. It’s time for fun!

Across The Universe Newsl | December 29

Across The Universe News | December 29:

Artist's concept of formation of asteroids



Pardawn Me, Dear Readers,

Far away from Earthlings who look forward to a new year, Dawn looks forward to a new world. On the far side of the sun, the interplanetary explorer is closing in on Ceres, using its advanced ion propulsion system to match solar orbits with the dwarf planet.

Since breaking out of orbit around the giant protoplanet Vesta in September 2012, the spaceship has patiently flown in interplanetary cruise. That long mission phase is over, and now Dawn is starting the Ceres chapter of its extraordinary extraterrestrial expedition. Configured for its approach phase, the craft is following a new and carefully designed course described in detail last month. In March it will slip ever so gracefully into orbit for an ambitious and exciting exploration of the alien world ahead.

Over the past year, we have provided previews of the major activities during all the phases of Dawn’s mission at Ceres. This month, let’s take a look at Ceres itself, an intriguing and mysterious orb that has beckoned for more than two centuries. Now, finally, after so long, Earth is answering the cosmic invitation, and an ambassador from our planet is about to take up permanent residence there. Over the course of Dawn’s grand adventure, our knowledge will rocket far, far beyond all that has been learned before.



There can be two accounts of Ceres: its own history, which dates back to near the dawn of the solar system almost 4.6 billion years ago, and its history in the scope of human knowledge, which is somewhat shorter. Both are rich topics, with much more than we can cover here (or in the first log for this entire mission), but let’s touch on a few tidbits. We begin with the latter history.

In 1800, the known solar system contained seven planets: Mercury, Venus, Earth (home to some of our readers), Mars, Jupiter, Saturn and Uranus. This reflected a new and sophisticated scientific understanding, because Uranus had first been noticed in telescopes not long before, in 1781. (The other planets had been known to ancient sky watchers.) Even before William Herschel’s fortuitous sighting of a planet beyond Saturn, astronomers had wondered about the gap between Mars and Jupiter and speculated about the possibility of a planet there. Although some astronomers had searched, their efforts had not yielded a new planet.

Giuseppe Piazzi

Giuseppe Piazzi points the way to his discovery, the planet Ceres. (Dawn’s route there is more complex than Piazzi might have guessed.) Credit: Osservatorio Astronomico di Palermo
Astronomer Giuseppe Piazzi was not looking for a planet on Jan. 1, 1801, but he spotted an unfamiliar dot of light that wandered slowly among the stars. He named it for Ceres, the Roman goddess of agriculture, and if you had cereal this morning, you have already had an etymological connection with the goddess.

The Dawn project worked with the International Astronomical Union (IAU) to formalize a plan for names on Ceres that builds upon and broadens Piazzi’s theme. Craters will be named for gods and goddesses of agriculture and vegetation from world mythology. Other features will be named for agricultural festivals.

Because Ceres was fainter than the other known planets, it was evident that it was smaller. Nevertheless, many astronomers considered it to be a planet too.

It is worth noting the significance of this. Modern astronomy had chanced upon only one other planet, so Piazzi’s discovery was A Big Deal. When a new chemical element was found a couple of years later, it was named cerium in tribute to the new planet Ceres. (Uranus had been similarly honored with the 1789 naming of uranium. That element’s peculiar property of emitting radiation would not be known for another century.)

In the six years following the discovery of Ceres, three more bodies were detected orbiting between Mars and Jupiter. (One of them is Vesta, now known in spectacular detail thanks to Dawn’s extensive exploration in 2011-2012.) There then ensued a gap of more than 38 years before another was found, so for well over a generation, the sun’s family of planets was unchanged.

So if you had been reading about all this 200 years ago, there would have been at least two important differences from now. One is that your Internet connection would have been considerably slower. The other is that you might have learned in school or elsewhere that Ceres was a planet.

In 1846, a planet was discovered beyond Uranus, and we call it Neptune. Nothing else of comparable size has subsequently been seen in our solar system.

With scientific knowledge and technology progressing in the middle of the nineteenth century, new objects were glimpsed between Mars and Jupiter. As more and more were seen over the years, what we now know as the main asteroid belt was gradually recognized. Terminology changed too. One of the great strengths of science is that it advances, and sometimes we have to modify our vocabulary to reflect the improved, refined view of the universe.

By the time Pluto was sighted in 1930, Ceres had long been known as a “minor planet” and an “asteroid.” For a while thereafter, Pluto enjoyed planetary status similar to what Ceres had had. In fact, in 1940, scientists named two more additions to the periodic table of the elements neptunium and plutonium. While the histories are not identical, there is a certain parallel, with more and more objects in Pluto’s part of the solar system later being found. Terminology changed again: Pluto was subsumed into the new category of “dwarf planets” defined by the IAU in 2006. Ceres was the first body to be discovered that met the criteria established by the IAU, and Pluto was the second. (Spacecraft are now on their way to both dwarf planets: Dawn to orbit Ceres 214 years after its discovery and the wonderful New Horizons mission to fly past Pluto 85 years after it was found.)

Four views of Ceres taken by the Hubble telescope

Four views of Ceres as it rotates, as seen with Hubble Space Telescope, are the best we have so far. (The brightest feature has been exaggerated here.) As summarized in October, Dawn’s pictures will surpass this quality within a month, revealing details never seen before. Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), and L. McFadden (University of Maryland, College Park)
We discussed this new nomenclature in some detail shortly after it was adopted. We understand that the designation then, as now, is controversial among some scientists and the public, and there are strong emotions on this topic. We will not delve into it here (nor in the blog comments below), preferring instead to focus on the extraordinary successes of science, the great power of the scientific method and the thrill of bold adventures far from home. The Dawn team remains both unperturbed and confident in what to call this intriguing and alluring world: we call it “Ceres.” And our goal is to develop that faint smudge of light amidst the stars into a richly detailed portrait.

One of the advances of science was the recognition that Ceres really is entirely different from typical residents of the main asteroid belt. It is a colossus! There are millions upon millions of asteroids, and yet Ceres itself contains roughly 30 percent of the mass in that entire vast region of space. By the way, Vesta, the second most massive body there, constitutes about eight percent of the asteroid belt’s mass. It is remarkable that Dawn will single-handedly explore around 40 percent of the asteroid belt’s mass.

With an equatorial diameter of about 605 miles (975 kilometers), a value that Dawn will refine very soon, Ceres is the largest body between the sun and Pluto that a spacecraft has not yet visited. It is occasionally described as being comparable in size to Texas, which is like comparing a basketball to a flat sheet of paper. Ceres has a surface area 38 percent of that of the continental United States, or four times the area of Texas. (Nevertheless, until Dawn shows evidence to the contrary, we will assume Texas has more rodeos.) It is nearly a third of the area of Europe and larger than the combined lands of France, Germany, Italy, Norway, Spain, Sweden and the United Kingdom. Such an expansive place offers the promise of tremendous diversity and many marvelous and exciting sights to behold. Earth is about to be introduced to a fascinating new world.

How did Ceres come to be? And why is that being phrased as a question instead of a more declarative introduction to the history and nature of this dwarf planet? For that matter, why is this paragraph composed exclusively of questions? At least this sentence isn’t a question, right? OK, really, shouldn’t we stay more on topic?

At the dawn of the solar system almost 4.6 billion years ago, the young sun was surrounded by a swirling cloud of dust and gas. Sometimes some particles would happen to hit and stick together. Then more and more and more particles would stick to them, and eventually these agglomerations would grow so large that their gravity would pull in even more material. It was through mechanisms like this that the planets formed.

But when massive Jupiter developed, its powerful gravity terminated the growth of objects nearby, leaving bits and pieces as asteroids. Ceres and Vesta, already sizable by then, might have grown to become even larger, each incorporating still more of the nearby material, had Jupiter not deprived them of such an opportunity. Not having made it to full planetary proportions, Ceres and Vesta are known as protoplanets, and studying them provides scientists with insight into the largest building blocks of planets and into worlds that are intriguing in their own rights.



Artist's concept of formation of asteroids


Dust and gas surrounding the sun coalesced into planets and asteroids, as depicted in this artist’s view. Credit: William Hartmann, Courtesy of UCLA
Ceres apparently formed far enough from the sun under conditions cool enough for it to hang on to water molecules. Indeed, scientists have good reason to believe that water (mostly in the form of ice) may make up an astonishing 30 percent of its mass. Ceres may contain more water than Mars or any other body in the inner solar system except Earth. (Comets, of course, have high proportions of water too, but they are so minuscule compared to this behemoth that each one harbors a quite negligible amount of water when measured against Ceres’ huge inventory.)

Although some of the moons of the outer planets also are ice and rock, and they display very interesting characteristics to the impressive and capable spacecraft that have flown past (in some cases repeatedly, as the craft orbited the host planet), no probe has had the capability to linger in orbit around any of them. Dawn’s in-depth exploration of Ceres will yield more detailed and complete views than we have obtained of any icy moon.

Radioactive elements incorporated into Ceres when it was forming would supply it with some heat, and its great bulk would provide thermal insulation, so it would take a very long time for the heat to escape into space. The sun, faraway though it is, adds still more heat. As a result, there may be some water warm enough to be liquid. (The concentration of any chemical impurities in the water that affect its freezing point, as salt does, may make an important difference in how much is liquid.) This distant, alien world may have lakes or even oceans of liquid water deep underground. What a fantastic possibility!

There will be no liquid on the frigid surface. Even ice on the surface, exposed to the cold vacuum of space, would sublimate before long. But ice could be just beneath the surface, perhaps well less than a yard (a meter) deep.

Ceres then may have a thin, dusty crust over a mantle rich in ice that might be more than 60 miles (100 kilometers) thick. Its warmer core is likely composed mostly of rock.

As heat dissipated from Ceres’ interior over the eons, it may have undergone convection, with the warmer material rising and cooler material sinking very slowly. This is reminiscent of what occurs in pot of heated water and in Earth’s interior. Even if it did occur at some time in Ceres’ history, it probably is not happening any longer, as too much heat would have been lost by now, so there would not be enough left to power the upward movement of warm material. But the convective process might have written its signature in structures or minerals left behind when ice sublimated after being pushed to the surface. Dawn’s photos of geological features and measurements of the composition may provide a window to forces in the interior of the protoplanet sometime in its past.

Even if convection is no longer occurring, Ceres is not entirely static. We have very tantalizing information from a marvelously productive far-infrared space telescope named for the only known astronomer who found a planet before Piazzi made his discovery. The Herschel Space Observatory recently detected a tiny amount of water vapor emanating from the distant dwarf planet. Scientists do not know how the water vapor makes it into space. It might be from ice sublimating (possibly following a powerful impact that exposed subsurface ice) or perhaps from geysers or even erupting cryovolcanoes (“cold volcanoes”) powered by heat that Ceres has retained since its formation. In any case, Herschel saw water, albeit in very, very small quantity.

It is not certain whether water vapor is there all the time. It is unknown whether, for example, it depends on solar heating and hence where Ceres is in its somewhat elliptical orbit around the sun (not as circular as Earth’s orbit but more circular than Mars’), which requires 4.6 years to complete.

Even if the water vapor is present during Dawn’s 1.3-year primary mission in orbit, it would be extremely difficult to detect. Herschel made its findings when our ship was already far, far from Earth, well along its interplanetary itinerary. The probe’s sensors were designed for studying the solid surfaces of airless bodies, not an exceedingly tenuous veil of water molecules. For context, the water vapor Herschel measured is significantly less dense than Earth’s atmosphere is even far above the International Space Station, which orbits in what most people consider to be the vacuum of space. Dawn will not need windshield wipers! Nevertheless, as we saw in February, the Dawn team, ever creative and dedicated to squeezing as much out of the mission as possible, investigated techniques this year that might be effective in searching for an exceptionally thin vapor. They have augmented the plan with many hours of observations of the space above Ceres when the spacecraft is over the night side during its first science orbit in April and May at an altitude of 8,400 miles (13,500 kilometers). It is possible that if there is some water vapor, the instruments may pick up a faint signature in the sunlight that passes through it.

Regardless of the possibility of detecting traces of water from Ceres, Dawn will focus its measurements on the uncharted surface and the interior, as it did at Vesta. Vesta displayed landscapes battered by craters from impacts during more than 4.5 billion years in the rough and tumble asteroid belt. Ceres has spent most or all of its history also in the asteroid belt, but it is possible it will not show its age so clearly. Ice, although very hard at such low temperatures, is not as hard as rock. So it may be that the surface gradually “relaxes” after an impact, just as your skin restores its shape after pressure has been removed. Craters older than a few tens of millions of years may have slowly disappeared. (That may sound old, but it is a small fraction of Ceres’ lifetime.) Near the poles, where it is colder so ice is harder, the scars of impact craters may be preserved for longer.

Ceres has more than water-ice and rock. It probably contains organic materials, some produced by chemical processes with the minerals already there and some delivered by asteroids that fell to its surface. This is noteworthy, because water and organic chemicals are ingredients for life. The combination of Ceres’ internal heat and the weak but persistent heating from the sun provides energy, which also is essential for life. Even if the possibility of life itself there is extremely remote (and it is beyond Dawn’s capability to detect), the conditions for “prebiotic” chemistry would be tremendously interesting. That is why, as we explained in August, we want to protect the special environment on the ground from contamination by the terrestrial chemicals in our orbiting spacecraft.



Image of Ceres taken by the Dawn spacecraft.


Dawn acquired this picture of Ceres on Dec. 1, as described last month. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
While there is more known about Ceres, there is much, much more that is unknown. Dawn seeks to discover many of the secrets of this unfamiliar, fascinating member of the solar system family. One of the measures of its success would be if, upon answering many of our questions about Ceres, we are left with even more questions. Now on the threshold of an old world which will be new to us, we do not have long to wait for the great rewards of new knowledge, new insight, new thrills and new mysteries to solve.

Dawn is 382,000 miles (614,000 kilometers) from Ceres, or 1.6 times the average distance between Earth and the moon. It is also 3.77 AU (351 million miles, or 564 million kilometers) from Earth, or 1,500 times as far as the moon and 3.84 times as far as the sun today. Radio signals, traveling at the universal limit of the speed of light, take one hour and three minutes to make the round trip.

Dr. Marc D. Rayman

8:00 a.m. PST December 29, 2014