Posted on by Nancy Atkinson

Scientists Say Voyager 1 Has Left the Solar System, But Has It Really?

The edge of the solar system. Image Credit: NASA/JPL-Caltech

A new paper out today reports that the Voyager 1 spacecraft appears to have traveled beyond the influence of the Sun and exited the heliosphere. However, the data they cite is the same as what NASA Voyager scientists claimed in December 2012 was just a new region at the edge of the solar system that scientists previously didn’t know was there. They called it a “highway” of magnetic particles, shepherding Voyager 1 out into interstellar space, whereas the new paper put out by the American Geophysical Union says Voyager 1 has crossed a “heliocliff” and into interstellar space.

JPL spokesperson Jia-Rui Cook had just heard of the paper when Universe Today called this morning to verify the findings of the new paper. “Our last statement about this was the critical thing we were looking for was a change in the magnetic field data,” she said via phone. “This paper does not appear to address the magnetic field data.”

UPDATE: NASA has issued a statement regarding this issue:

“The Voyager team is aware of reports today that NASA’s Voyager 1 has left the solar system,” said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif. “It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called ‘the magnetic highway’ where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed.”

Cook told Universe Today that Voyager Project Scientist Ed Stone was out of the country, and she was trying to get in touch with him to verify the paper’s claims that Voyager has left the solar system, and he obviously wasted no time in setting the record straight.

In another update, the AGU reissued the press release with a different title to “to better represent the findings reported in the study.” The initial headline was “Voyager 1 Has Left the Solar System, Sudden Changes in Cosmic Rays Indicate,” and the new headline is “Voyager 1 has entered a new region of space, sudden changes in cosmic rays indicate.” So, basically, the new paper was just iterating the previous findings.

(End of updates)

The authors of the new paper, William Webber and F.B. McDonald, cite the events of last summer when Voyager 1 measured drastic changes in radiation levels, more than 18 billion km (11 billion miles) from the Sun. On July 28, 2012 the level of lower-energy particles originating from inside our Solar System dropped by half. However, in three days, the levels had recovered to near their previous levels. But then the bottom dropped out at the end of August, where anomalous cosmic rays (cosmic rays trapped in the outer heliosphere) all but vanished, dropping to less than 1 percent of previous amounts. At the same time, galactic cosmic rays – cosmic radiation from outside of the solar system – spiked to levels not seen since Voyager’s launch, with intensities as much as twice previous levels.

“Within just a few days, the heliospheric intensity of trapped radiation decreased, and the cosmic ray intensity went up as you would expect if it exited the heliosphere,” said Webber in an AGU press release. Webber is a professor emeritus of astronomy at New Mexico State University in Las Cruces. He called this transition boundary the “heliocliff.”

In the Geophysical Research Letters article, the authors say, “It appears that [Voyager 1] has exited the main solar modulation region, revealing [hydrogen] and [helium] spectra characteristic of those to be expected in the local interstellar medium.”

However, last December in a NASA press conference, the Voyager team said they infered this region is still inside our solar bubble because the direction of the magnetic field lines has not changed. The direction of these magnetic field lines is predicted to change when Voyager breaks through to interstellar space.

“We believe this is the last leg of our journey to interstellar space,” Stone said during the press conference. “Our best guess is it’s likely just a few months to a couple years away. The new region isn’t what we expected, but we’ve come to expect the unexpected from Voyager.”

We’ll provide more information on this discrepancy between the interpretations of the events when we hear more from the Jet Propulsion Laboratory.

Posted on by David Dickinson

U.S. To Restart Plutonium Production for Deep Space Exploration

A marshmellow-sized Pu-238 pellet awaits a space mission. (Credit: The Department of Energy).

The end of NASA’s plutonium shortage may be in sight. On Monday March 18th,  NASA’s planetary science division head Jim Green announced that production of Plutonium-238 (Pu-238) by the United States Department of Energy (DOE) is currently in the test phases leading up to a restart of full scale production.

“By the end of the calendar year, we’ll have a complete plan from the Department of Energy on how they’ll be able to satisfy our requirement of 1.5 to 2 kilograms a year.” Green said at the 44th Lunar and Planetary Science Conference being held in Woodlands, Texas this past Monday.

This news comes none too soon. We’ve written previously on the impending Plutonium shortage and the consequences it has for future deep space exploration. Solar power is adequate in most cases when you explore the inner solar system, but when you venture out beyond the asteroid belt, you need nuclear power to do it.

Production of the isotope Pu-238 was a fortunate consequence of the Cold War.  First produced by Glen Seaborg in 1940, the weapons grade isotope of plutonium (-239) is produced via bombarding neptunium (which itself is a decay product of uranium-238) with neutrons. Use the same target isotope of Neptunium-237 in a fast reactor, and Pu-238 is the result. Pu-238 produces 280x times the decay heat at 560 watts per kilogram versus weapons grade Pu-239  and is ideal as a compact source of energy for deep space exploration.

Since 1961, over 26 U.S. spacecraft have been launched carrying Multi-Mission Radioisotope Thermoelectric Generators (MMRTG, or formerly simply RTGs) as power sources and have explored every planet except Mercury. RTGs were used by the Apollo Lunar Surface Experiments Package (ALSEP) science payloads left on by the astronauts on the Moon, and Cassini, Mars Curiosity and New Horizons enroute to explore Pluto in July 2015 are all nuclear powered.

Plutonium powered RTGs are the only technology that we have currently in use that can carry out deep space exploration. NASA’s Juno spacecraft will be the first to reach Jupiter in 2016 without the use of a nuclear-powered RTG, but it will need to employ 3 enormous 2.7 x 8.9 metre solar panels to do it.

The plutonium power source inside the Mars Science Laboratory's MMRTG during assembly at the Idaho National Laboratory. (Credit: Department of Energy?National Laboratory image under a Creative Commons Generic Attribution 2.0 License).
The plutonium power source inside the Mars Science Laboratory’s MMRTG during assembly at the Idaho National Laboratory. (Credit: Department of Energy/Idaho National Laboratory image under a Creative Commons Generic Attribution 2.0 License).

The problem is, plutonium production in the U.S. ceased in 1988 with the end of the Cold War. How much Plutonium-238 NASA and the DOE has stockpiled is classified, but it has been speculated that it has at most enough for one more large Flag Ship class mission and perhaps a small Scout class mission. Plus, once weapons grade plutonium-239 is manufactured, there’s no re-processing it the desired Pu-238 isotope. The plutonium that currently powers Curiosity across the surface of Mars was bought from the Russians, and that source ended in 2010. New Horizons is equipped with a spare MMRTG that was built for Cassini, which was launched in 1999.

Technicians handle an RTG at the Payload Hazardous Servicing Facility at the Kennedy Space Center for the Cassini spacecraft. (Credit: NASA).
Technicians handle an RTG at the Payload Hazardous Servicing Facility at the Kennedy Space Center for the Cassini spacecraft. (Credit: NASA).

As an added bonus, plutonium powered missions often exceed expectations as well. For example, the Voyager 1 & 2 spacecraft had an original mission duration of five years and are now expected to continue well into their fifth decade of operation. Mars Curiosity doesn’t suffer from the issues of “dusty solar panels” that plagued Spirit and Opportunity and can operate through the long Martian winter. Incidentally, while the Spirit and Opportunity rovers were not nuclear powered, they did employ tiny pellets of plutonium oxide in their joints to stay warm, as well as radioactive curium to provide neutron sources in their spectrometers. It’s even quite possible that any alien intelligence stumbles upon the five spacecraft escaping our solar system (Pioneer 10 & 11, Voyagers 1 & 2, and New Horizons) could conceivably date their departure from Earth by measuring the decay of their plutonium power source. (Pu-238 has a half life of 87.7 years and eventually decays after transitioning through a long series of daughter isotopes into lead-206).

New Horizons in the Payload Hazardous Servicing Facility at the Kennedy Space Center. Note the RTG (black) protruding from the spacecraft. (Credit: NASA/Uwe W.)
New Horizons in the Payload Hazardous Servicing Facility at the Kennedy Space Center. Note the RTG (black) protruding from the spacecraft. (Credit: NASA/Uwe W.)

The current production run of Pu-238 will be carried out at the Oak Ridge National Laboratory (ORNL) using its High Flux Isotope Reactor (HFIR). “Old” Pu-238 can also be revived by adding newly manufactured Pu-238 to it.

“For every 1 kilogram, we really revive two kilograms of the older plutonium by mixing it… it’s a critical part of our process to be able to utilize our existing supply at the energy density we want it,” Green told a recent Mars exploration planning committee.

Still, full target production of 1.5 kilograms per year may be some time off. For context, the Mars rover Curiosity utilizes 4.8 kilograms of Pu-238, and New Horizons contains 11 kilograms. No missions to the outer planets have left Earth since the launch of Curiosity in November 2011, and the next mission likely to sport an RTG is the proposed Mars 2020 rover. Ideas on the drawing board such as a Titan lake lander and a Jupiter Icy Moons mission would all be nuclear powered.

Engineers perform a fit check of the MMRTG on Curiousity at the Kennedy Space Center. The final installation of the MMRTG occured the evening prior to launch. (Credit: NASA/Cory Huston).
Engineers perform a fit check of the MMRTG on Curiosity at the Kennedy Space Center. The final installation of the MMRTG occurred the evening prior to launch. (Credit: NASA/Cory Huston).

Along with new plutonium production, NASA plans to have two new RTGs dubbed Advanced Stirling Radioisotope Generators (ASRGs) available by 2016. While more efficient, the ASRG may not always be the device of choice. For example, Curiosity uses its MMRTG waste heat to keep instruments warm via Freon circulation.  Curiosity also had to vent waste heat produced by the 110-watt generator while cooped up in its aero shell enroute to Mars.

Cutaway diagram of the Advanced Stirling Radioisotope Generator. (Credit: DOE/NASA).
Cutaway diagram of the Advanced Stirling Radioisotope Generator. (Credit: DOE/NASA).

And of course, there are the added precautions that come with launching a nuclear payload. The President of the United States had to sign off on the launch of Curiosity from the Florida Space Coast. The launch of Cassini, New Horizons, and Curiosity all drew a scattering of protesters, as does anything nuclear related. Never mind that coal fired power plants produce radioactive polonium, radon and thorium as an undesired by-product daily.

An RTG (in the foreground on the pallet) left on the Moon by astronauts during Apollo 14. (Credit: NASA/Alan Shepard).
An RTG (in the foreground on the pallet) left on the Moon by astronauts during Apollo 14. (Credit: NASA/Alan Shepard).

Said launches aren’t without hazards, albeit with risks that can be mitigated and managed. One of the most notorious space-related nuclear accidents occurred early in the U.S. space program with the loss of an RTG-equipped Transit-5BN-3 satellite off of the coast of Madagascar shortly after launch in 1964. And when Apollo 13 had to abort and return to Earth, the astronauts were directed to ditch the Aquarius Landing Module along with its nuclear-powered science experiments meant for the surface of the Moon in the Pacific Ocean near the island of Fiji. (They don’t tell you that in the movie) One wonders if it would be cost effective to “resurrect” this RTG from the ocean floor for a future space mission. On previous nuclear-equipped launches such as New Horizons, NASA placed the chance of a “launch accident that could release plutonium” at 350-to-1 against  Even then, the shielded RTG is “over-engineered” to survive an explosion and impact with the water.

But the risks are worth the gain in terms of new solar system discoveries. In a brave new future of space exploration, the restart of plutonium production for peaceful purposes gives us hope. To paraphrase Carl Sagan, space travel is one of the best uses of nuclear fission that we can think of!

Posted on by Tammy Plotner

Grand Spiral Galaxy Graced By Faded Supernova

One of the most lovely deep space objects to observe is the grand-design spiral galaxy and there are few so grand as NGC 1637. Located in the constellation of Eridanus and positioned approximately 35 million light years away, this twisted beauty was home to a radical supernova event just 14 years ago. Now astronomers are taking a close look at the resultant damage caused by the stellar explosion and giving us some pretty incredible views of the galaxy as well.

When viewing NGC 1637, it seems as if the galaxy itself is evenly distributed, but take a closer look. In this image you will notice the spiral arm to the top left is much more openly constructed and stretches out a bit further than the more concentrated and stubby spiral arm to its opposite side. You will also notice the more compact arm has the appearance of being cut through its mid-section. In whole, this particular appearance is what astronomers refer to as a “lopsided spiral galaxy”.

Now, let’s talk about what happened to disturb the peace…

In 1999, high atop Mt. Hamilton and near San Jose, California, the Lick Observatory was busy utilizing a telescope which specialized in searching for supernova events. Low and behold, they discovered one… a very bright one located in NGC 1637. Like all astronomical observations, the call went out immediately to other observatories to confirm their find and to gather support data. As with most dramatic events, SN 1999em was quickly and thoroughly researched by telescopes around the world – its magnitude carefully recorded and the resultant fading meticulously accounted for as the years have passed.

Better to burn out than to fade away? There are very few things in our natural world which can match the violent beauty of a supernova event. When a star ends its life in this way, it goes out with a bang, not a whimper. For their cosmic finale, they briefly outshine the combined light of all the stars contained within the host galaxy. Like snowflakes, each supernova is unique and the cataclysmic star within NGC 1637 was eight times more massive than our Sun.

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This video sequence starts with a view of the bright constellation of Orion (The Hunter). As we zoom in, we focus on an adjacent region of the constellation of Eridanus (The River) and a faint glow appears. This is the spiral galaxy NGC 1637, which appears in all its glory in the final view from ESO’s Very Large Telescope. In 1999 scientists discovered a Type II supernova in this galaxy and followed its slow fading over the following years. Credit: ESO/Nick Risinger

Go ahead. Take another look. During the confirmation observing runs, astronomers also imaged SN 1999em with the VLT and this data was combined with the Lick Observatory information to give us the spectacular view above. Caught in the spiral arm are young stars singing the blues amidst ethereal gas clouds and veiling dust lanes. NGC 1637 isn’t alone, either… You’ll see line of sight stars and even more galaxies in the background.

No rust here…

Original Story Source: ESO News Release.

Posted on by Nancy Atkinson

Closest Exoplanet Deserves a ‘Real’ Name, Says Uwingu

Information about Alpha Centauri Bb. Information about Alpha Centauri Bb. Credit: Planetary Habitability Laboratory/University of Puerto Rico/Arecibo

It’s time to “get real” about naming exoplanets, says Uwingu CEO and scientist Dr. Alan Stern. And so the latest project from the space funding startup company is a contest to name the nearest exoplanet, currently known as Alpha Centauri Bb.

“Let’s face it,” Stern told Universe Today, “the current names astronomers use for exoplanets are boring. The public is really excited about all the planets that are being found around other stars, but the names do nothing to help fuel that excitement. We’re giving the public the chance to name the closest exoplanet.”

Nominations for new names for Alpha Centauri Bb cost $4.99; votes for nominated names are $0.99. Proceeds from naming and voting will help fuel new Uwingu grants to fund space exploration, research, and education.

The names won’t be officially approved by the International Astronomical Union, but Stern said they will be similar to the names given to features on Mars by the mission science teams (such as Mt. Sharp on Mars –the IAU approved name is Aeolis Mons) that everyone ends up using.

“Or it’s like Pike’s Peak,” said Stern of the mountain in the Rocky Mountains in Colorado. “People started calling it that long ago and over time, it became the only name people recognized. This should be the wave of the future for planets and there’s no reason for the public not to get involved.”

So far, the IAU’s stance on naming exoplanets is that there is seemingly going to be so many of them, (we’re nearing the 1,000 mark) that it will be difficult to name them all.

In fact here is their official statement on their website:

In response to frequent questions about plans to assign actual names to extra-solar planets, the IAU sees no need and has no plan to assign names to these objects at the present stage of our knowledge. Indeed, if planets are found to occur very frequently in the Universe, a system of individual names for planets might well rapidly be found equally impracticable as it is for stars, as planet discoveries progress.

“The IAU has had ten years to do something about this and they haven’t done anything,” said Stern. “What we’re doing might be controversial, but that’s OK. It’s time to step up to the plate and do something.”

Previously Uwingu has offered the chance to create a “baby book” of names that can be used for exoplanets. For this contest, they are naming a specific planet, and the name getting the highest number of votes will be declared the public’s name for this mysterious new world. “Never before has the public been asked to choose its favorite name for a planet,” says Uwingu.

Anyone can nominate one or more names; anyone can vote. The namer of the most popular new name for alpha Cen Bb will receive prizes from Uwingu; there will also be prizes for runner-ups, and for all names that reach thresholds of 100, 1,000, and 10,000 votes.
uwingu

There are those who have been critical of Uwingu, but our stance is that Uwingu is so far the only group or organization to step forward with innovative, out-of-the-box ways to try and solve what seems to be a continuous, perennial problem: how to fund creative space and astronomy projects and move beyond the old tried and not always true methods of relying on government grants and subsidies or angel donors.

Former president of the IAU Planetary Systems Science body, Karen Meech told Universe Today last year that since the IAU is the only scientifically recognized arbiter of astronomical names, any contests for names from the public will not be officially recognized by the scientific community.

But, it’s obvious people love to name things and people are eventually going to start referring to endearing exoplanets with “real” names instead of the license-plate like names currently used.

“Who knows,” said Stern. “There could be a real Pandora or Tatooine out there.”

Check out the contest at Uwingu

Posted on by Fraser Cain

Import Fraser’s Super Science Circle to Understand Google+



Many people are still having a tough time wrapping their head around Google+. They go there and none of their friends are around. To solve this problem, I’ve created my Super Science Circle. This is a pre-made circle containing 400 people who actively post on Google+ about science topics. There are some big names there, including astronauts, professors, researchers, students, journalists, and lots of science enthusiasts. I carefully curate this list to make sure each and every person on the list is active and regularly posts about science.

So, if you want to understand Google+, and get over the idea that it’s a ghost town, all you need to do is import this circle and you’ll have a ready-made community overflowing with amazing content.

1. Click here to access the shared circle on Google+

2. Click “View Shared Circle”

3. Name your new circle and then click “Create or add to circles”

Posted on by Tammy Plotner

LOFAR Captures Giant Galaxy

Overlay of the new GRG (blue-white colors) on an optical image from the Digitized Sky survey. The inset shows the central galaxy triplet (image from Sloan Digital Sky Survey). The image is about 2 Mpc across.

Our Universe is full of surprises. Sometimes those surprises come in packages so overwhelmingly huge that it’s almost impossible for us to comprehend the size. Thus is the case of a newly discovered “giant galaxy”. It’s a galaxy which extends millions of light years across intergalactic space, covering an area as much as a half degree of sky. It’s a new class of monster – one called a Giant Radio Galaxy.

Thanks to the work of an international team of astronomers made up of about fifty members from various institutes and led by ASTRON astronomer, Dr. George Heald, there’s a new discovery which can be credited to the powerful International LOFAR Telescope (ILT). During a perpetual all-sky radio survey – the Multi-frequency Snapshot Sky Survey (MSSS) – the team captured some images which revealed a new radio source. This wasn’t just a weak signal that showed a new blotch. It was a source the size of the full Moon projected on the sky! The huge new radio emission appears to have originated up to hundreds of million of years ago from a single member of a interacting triple galaxy system and spread itself across a vast expanse of space.

Cataloged as UGC 09555, the parent galaxy system is located some 750 million light years from our solar system. Its central galaxy had been studied before and was known to have a flat radio spectrum – a signature of giant radio galaxies. Astronomers speculate when the trio interacted, material was released – spreading out over millions of light years and releasing very low radio frequencies. It’s a source that’s either very powerful, or it’s very old.

Enter LOFAR and the MSSS Survey…

As part of a well orchestrated attempt to image the expanse of the northern night sky at frequencies between 30 and 150 MHz, the radio researchers have taken a initial “shallow scan” image set. This new survey will allow astronomers to fashion an all-sky model which will eventually assist with much deeper observations. Thanks to LOFAR’s extreme sensitivity, ability to operate at low frequencies and suitability to observe old sources, the survey was able to reveal this gargantuan galaxy. Picture its size again in your mind. This Giant Radio Galaxy covers as much sky as the Moon, yet it’s 750 million light years away! As the MSSS Survey continues to scan the skies, who knows what may yet be discovered?

With capabilities as sensitive as some of the world’s greatest radio telescopes, such as the Very Large Array (VLA) in the USA, ASTRON’s Westerbork Synthesis Radio Telescope (WSRT), and the Giant Metrewave Radio Telescope (GMRT) in India, LOFAR will take discoveries such as Giant Radio Galaxies to the next level. It will reveal objects missed by previous surveys and the broad bandwidth coverage may show us even more cosmic wonders.

Really big ones…

Original News Source: Netherlands Institute for Radio Astronomy News Release.

Posted on by Jason Major

Enceladus’ Jets Reach All the Way to its Sea

Saturn's moon Enceladus sprays its salty sea out into space. Those plumes are rich in phosphates. (NASA/JPL/SSI/J. Major)

Thanks to the Cassini mission we’ve known about the jets of icy brine spraying from the south pole of Saturn’s moon Enceladus for about 8 years now, but this week it was revealed at the 44th Lunar and Planetary Science Conference outside Houston, Texas that Enceladus’ jets very likely reach all the way down to the sea — a salty subsurface sea of liquid water that’s thought to lie beneath nearly 10 kilometers of ice.

Enceladus’ jets were first observed by the Cassini spacecraft in 2005. The jets constantly spray fine particles of ice into space which enter orbit around Saturn, creating the hazy, diffuse E ring in which Enceladus resides.

Emanating from deep fissures nicknamed “tiger stripes” that gouge the 512-km (318-mile) -wide moon’s south pole the icy jets — and the stripes — have been repeatedly investigated by Cassini, which has discovered that not only do the ice particles contain salts and organic compounds but also that the stripes are surprisingly warm, measuring at 180 Kelvin (minus 135 degrees Fahrenheit) — over twice as warm as most other regions of the moon.

Read more: Enceladus’ Salty Surprise

Where the jets are getting their supply of liquid water has been a question scientists have puzzled over for years. Is friction caused by tidal stresses heating the insides of the stripes, which melts the ice and shoots it upwards? Or do the fissures actually extend all the way down through Enceladus’ crust to a subsurface ocean of liquid water, and through tidal pressure pull vapor and ice up to the surface?

"Baghdad Sulcus," one of many tiger stripe fissures on Enceladus (NASA/JPL/SSI)
“Baghdad Sulcus,” one of many tiger stripe fissures on Enceladus (NASA/JPL/SSI)

Researchers are now confident that the latter is the case.

In a presentation at the Lunar and Planetary Science Conference titled “How the Jets, Heat and Tidal Stresses across the South Polar Terrain of Enceladus Are Related” (see the PDF here) Cassini scientists note that the amount of heating due to tidal stress seen along Enceladus’ tiger stripes isn’t nearly enough to cause the full spectrum of heating observed, and the “hot spots” that have been seen don’t correlate with the type of heating caused by shear friction.

Instead, the researchers believe that heat energy is being carried upwards along with the pressurized water vapor from the subsurface sea, warming the areas around individual vents as well as serving to keep their channels open.

With 98 individual jets observed so far on Enceladus’ south polar terrain and surface heating corresponding to each one, this scenario, for lack of a better term… seems legit.

What this means is that not only does a moon of Saturn have a considerable subsurface ocean of liquid water with a heat source and Earthlike salinity (and also a bit of fizz) but also that it’s spraying that ocean, that potentially habitable environment, out into local space where it can be studied relatively easily — making Enceladus a very intriguing target for future exploration.

“To touch the jets of Enceladus is to touch the most accessible salty, organic-rich, extraterrestrial body of water and, hence, habitable zone, in our solar system.”

– Cassini imaging team leader Carolyn Porco et al.

Enceladus is actively spraying its habitable zone out into space (NASA/JPL/SSI)
Enceladus is actively spraying its habitable zone out into space (NASA/JPL/SSI)

Research notes via C. Porco, D. DiNino, F. Nimmo, CICLOPS, Space Science Institute at Boulder, CO, and Earth and Planetary Sciences at UC Santa Cruz, CA.

Top image: color-composite of Enceladus made from raw Cassini images acquired in 2010. The moon is lit by reflected light from Saturn while the jets are backlit by the Sun. 

Posted on by Bob King

The Curious and Confounding Story Of How Arcturus Electrified Chicago

Find Arcturus easily by using the handle of the Big Dipper. This map shows the sky facing northeast around 9:30-10 p.m. local time in late March. Stellarium

Every star has a story but some are more curious than others. The star Arcturus has an electrifying story with a mysterious twist involving the 1933 World’s Fair.

If you step out on a clear night in mid-March and follow the curve of the Big Dipper’s handle toward the eastern horizon, you’ll come face to face with Arcturus, the 4th brightest star in the sky. Pale orange and fluttering in the low air like a candle in the breeze, Arcturus is a bellwether of spring. By late May it shines high in the south at the onset of night. For the moment, the star hunkers down in the east, sparking through tree branches and over neighborhood rooftops.

The name Arcturus comes from the ancient Greek word “arktos” for bear and means “Bear Watcher”. That’s easy to remember because he follows Ursa Major the Great Bear, the brightest part of which is the Big Dipper, across the spring sky.

Arcturus is 37 light years from Earth and classified as an orange giant star. It spans 25 times the sun's diameter.
Arcturus is 37 light years from Earth and classified as an orange giant star. It spans 25 times the sun’s diameter and shines 113 times more brightly.

It was another spring 80 years ago on May 27,1933, that the city of Chicago opened its Century of Progress Exposition as part of the World’s Fair highlighting progress in science and industry. 40 years prior in 1893 the city had hosted its first big fair, the World’s Columbian Exposition.

In the early 1930s astronomers estimated Arcturus’ distance at 40 light years. Edwin Frost, retired director of the Yerkes Observatory in Williams Bay, Wis., home to the world’s largest refracting telescope, hit upon the idea of using Arcturus to symbolically link both great fairs which were separated by a span of 40 years.

Poster from the Century of Progress Exposition also called the Chicago World's Fair. Its theme was the significance of science and and improvements brought about by science. The event was celebrated on Chicago's 100th anniversary. Credit: Wikipedia
Poster from the Century of Progress Exposition also called the Chicago World’s Fair. Its theme was the significance of science and how it had bettered mankind. The event was celebrated on Chicago’s 100th anniversary. Credit: Wikipedia

At the time, the photocell, a device that produces an electric current when exposed to light, was all the rage. Clever entrepreneurs had figured out how to take advantage of light’s ability to knock electrons loose from atoms to open doors and count shoppers automatically. They’re still in wide use today from burglar alarms to toilets that magically flush when you step away.

Edwin Frost around the time he was director of Yerkes Observatory in Williams Bay, Wis. Credit: National Academy of Sciences
Edwin Frost around the time he was director of Yerkes Observatory in Williams Bay, Wis. Credit: National Academy of Sciences

Technological innovation through scientific progress was the theme of the 1933 fair. What better way, thought Frost, to highlight the benefits of science and link both great events than by focusing the light of Arcturus onto a photocell and using the electric current generated to flip a switch that would turn on the lights at the fair’s opening.

Though we now know Arcturus is 37 light years away, at the time it was thought to be about 40. The light that left the star during the first world’s fair in 1893 would arrive just in time 40 years later to open the next.  Arcturus was not only at the right distance but bright and easy to see during May at the fair’s opening. Could a more perfect marriage of poetry and science ever be arranged?

Edwin B. Frost (left), Christian T. Elvey (center), and Otto Struve (right) examine a General Electric photoelectric relay and a F.P.-54 Pliotron tube that will help activate the lights of the "Century of Progress," thus opening the Chicago world fair of 1933. University of Chicago Photographic Archive, apf6-00477, Special Collections Research Center, University of Chicago Library.
From left: Edwin B. Frost, Christian T. Elvey, staff, and Otto Struve, Yerkes director, examine a General Electric photoelectric relay and the photocell tube that will help activate the lights of the “Century of Progress,” thus opening the Chicago world fair of 1933. Courtesy Yerkes Observatory

Although Yerkes Observatory was picked for the job, backups were needed in the event of cloudy skies. In the end, telescopes at the University of Illinois Observatory in Urbana, Harvard College Observatory and Allegheny Observatory in Pittsburgh all participated in the grand event.

On May 27, 1933 shortly before the appointed time, Century of Progress Fair president Rufus C. Dawes spoke to a crowd of some 30,000 people assembled in the courtyard at the Hall of Science:

“We recall the great Columbian Exposition of 1893. Never will its beauty be surpassed.
Never will there be held an exposition of more lasting value to this city. It was for Chicago a great triumph.”

Visitors throng the Hall of Science at the Chicago World's Fair in 1933. Click to enlarge Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_027)
Visitors throng the Hall of Science at the Chicago World’s Fair in 1933, site of the Arcturus lighting ceremony. Click to enlarge Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_027)

“We remind ourselves of that triumph tonight by taking rays of light that left the star Arcturus during the period of that exposition and which have traveled at the rate of 186,000 miles a second until at last they have reached us. We shall use these rays to put into operation the mysterious forces of electricity which will make light our grounds, decorate our buildings with brilliant colors, and move the machinery of the exposition.”

Above the speaker’s platform hung a large illuminated panel, the bottom half of which displayed a map of the eastern U.S. with the locations of the four observatories. The top half contained the instruments that completed the circuit from Arcturus to a searchlight in the Hall of Science.

When light beams from the star Arcturus were picked up by photoelectric tubes at four observatories, signals flashed on this display board on the rostrum of the Hall of Science to the show the audience how the official lighting. Click to enlarge. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_016)
When light beams from the star Arcturus were picked up by photoelectric tubes at four observatories, signals flashed on this display board on the rostrum of the Hall of Science to the show the audience. Click to enlarge. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_016)

At 9:15 p.m. each of the four observatories borrowed bits of Arcturus’ light, focused them onto their respective photocells and sent the electric current by Western Union telegraph lines to the Chicago fairgrounds.

In the book Fair Management – The Story of a Century of Progress, author Lenox Lohr described what happened next. One of the speakers, probably Philip Fox, director of Chicago’s Adler Planetarium, stepped to the podium to issue the final instructions :

“Harvard, are you ready?”
“Yes.”
A red glow ran across the map from Cambridge to Chicago.
“Is Allegheny ready?”
“Ready.”
“Illinois ready?”
“Yes.”
“Yerkes?”
“Let’s go.”

The switch was thrown, and a searchlight at the top of the Hall of Science shot a great white beam across the sky.”

The crowd went bananas. It was such a huge hit, nearby Elgin Observatory was pressed into operation to light the fair in similar fashion every night for the remainder of the season.

The Hall of Science area at the fair along with the Arcturus sign (far left) and a group of people creating a large star shape on a stage. Click for large version. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_017)
The Hall of Science area at the fair along with the Arcturus sign (far left) and a group of people creating a large star shape on a stage. Click for large version. Credit: Century of Progress Records, 1927-1952, University of Illinois at Chicago Library (COP_17_0002_00023_017)

Harnessing a distant star for mankind’s benefit. We marvel at the 1933 fair promoters and astronomers for conceiving of this most ingenious way of linking past and present.

That would be the end of a wonderful story if it wasn’t for one Ralph Mansfield. Mansfield, a student at the time at the University of Chicago, worked as a guide at Chicago’s Alder Planetarium, which was also involved in the lighting ceremony. Before passing away in 2007, Mansfield shared the story of how he was the one to point the telescope at Arcturus and fire up the fairground lights.

The Adler Planetarium on Chicago's Lake Michigan lakefront. Credit:Fritz Geller-Grimm
The Adler Planetarium on Chicago’s Lake Michigan lakefront. Credit:Fritz Geller-Grimm

I learned this while reading an article by Nathan B. Myron, PhD on the topic in which Mansfield sought to set the record straight. In his version, then-director of the Adler Planetarium, Philip Fox. was apprehensive about cloudy skies, so he arranged for Mansfield to set up a telescope in the balcony of the Hall of Science. As Fox delivered opening remarks, Mansfield used the Dipper’s Handle to find Arcturus in a lucky break in the clouds, and at the key moment, fed its light to the photocell. The spotlight fired up and the day was saved.

So which is the true story?

“It’s a bit of a mystery,” said Richard Dreiser, public information officer for Yerkes Observatory. “No one really knows absolutely.”

His sentiments were echoed by Bruce Stephenson, current curator at the Adler Planetarium: “The truth as far as we can ascertain it today is not really known. These things happened long ago.”

Most historical accounts indicate that four observatories participated, but Mansfield’s story remains. Will the real version please stand up?

Posted on by Nancy Atkinson

Remains of GRAIL Spacecraft Found on Lunar Surface

Before and after the GRAIL twins impacts on the Moon December 17, 2012. The LROC Narrow Angle Camera (NAC) directors were able to resolve the impact sites on February 28, 2013, revealing both to be about 5 meters in diameter. Upper panels show the area before the impact; lower panels after the impact. Arrows point to crater locations. LROC NAC observations M186085512R, M186078336L, M1116736474R and M1116736474L. Credit: NASA/GSFC/Arizona State University.

On December 17, 2012, the GRAIL mission came to an end, and the two washing machine-sized spacecraft performed a flying finale with a planned formation-flying double impact into the southern face of 2.5-kilometer- (1.5-mile-) tall mountain on a crater rim near the Moon’s north pole. The Lunar Reconnaissance Orbiter has now imaged the impact sites, which show evidence of the crashes.

But surprisingly, these impacts were not what was expected, says the LRO and GRAIL teams. The ejecta around both craters is dark. Usually, ejecta from craters is lighter in color – with a higher reflectance – than the regolith on surface.

“I expected the ejecta to be bright,” said LROC PI Mark Robinson at a press conference from the Lunar and Planetary Science Conference today, “because everybody knows impact rays on the Moon are bright. We are speculating it could be from hydrocarbons from the spacecraft.”

GRAIL A site seen before and after the impact event. Crater center is located at 75.609°N, 333.407°E/ Credit: NASA/GSFC/Arizona State University.
GRAIL A site seen before and after the impact event. Crater center is located at 75.609°N, 333.407°E/ Credit: NASA/GSFC/Arizona State University.

Typically ejecta from craters is brighter, since subsurface regolith tends to have a higher reflectance. The lunar regolith on the surface tends to be darker because of its exposure to the vacuum of space, cosmic radiation, solar wind bombardment, and micrometeorite impacts. Slowly over time, these processes tend to darken the surface soil.

Robinson said the hydrocarbons could have come from fuel left in the fuel lines (JPL estimated a quarter to half a kilogram of fuel may have remained in the spacecraft – so, not very much) or from the spacecraft itself, which is made out of carbon material.

GRAIL B site seen before and after impact event. Crater center is located at 75.651°N, 333.168°E. Credit: NASA/GSFC/Arizona State University.
GRAIL B site seen before and after impact event. Crater center is located at 75.651°N, 333.168°E. Credit: NASA/GSFC/Arizona State University.

Additionally, the impact craters’ shapes were not as expected. The impacts formed craters about 5 m (15 ft) in diameter, and there is little ejecta to the south – the direction from which the spacecraft were traveling. “The spacecraft came in at a 1 or 2 degree impact angle,” said Robinson, “so this not a normal impact, as all the ejecta went upstream in the direction of travel.”

“I was expecting to see skid marks, myself,” said GRAIL principal investigator Maria Zuber. She added that she was committed to using every bit of fuel to mapping the gravity field at as low an altitude as possible. “I was determined that we would not end the mission with unused fuel because that would have meant we could mapped it even lower.

The spacecraft did end up being able to map the Moon from 2 km above the surface, the lowest altitude from which any planetary surface has ever been mapped, creating an extremely high resolution map.

LRO Wide Angle Camera (WAC) image of the GRAIL impact area on the south side of the unnamed massif. Credit: NASA/GSFC/ASU.
LRO Wide Angle Camera (WAC) image of the GRAIL impact area on the south side of the unnamed massif. Credit: NASA/GSFC/ASU.

Robinson said he was skeptical that they could find the impact craters, since the team has yet to find the impact sites of the Apollo ascent stages, which should be much bigger than the GRAIL impacts.

“Finding the impact crater was like finding a needle in haystack,” Robinson said, “as the images are looking at an area that is about 8 km wide and 30 to 40 km tall, and we were looking for something that is a couple of pixels wide.”

Robinson said he spent hours looking for it with no luck, only to see it later when he was on a conference call and was just looking at it out of the corner of his eye.

“It was really fun to find the craters,” he said. LRO did take images in early January, but better images were taken on February 28, 2013.

While LRO’s camera was not able to image the actual impact since it occurred on the night-side of the Moon, the LAMP instrument (Lyman Alpha Mapping Project) on LRO was able to detect the plumes of the impacts.

Kurt Retherford, PI of LAMP said the UV spectrograph was pointed towards the limb of the Moon — and actually looking in the direction of the constellation Orion at the time of the GRAIL impact — to observe the gases coming out of the plumes. They did detect the two impact plumes which clearly showed an excess of emissions from hydrogen atoms. “We were excited to see this detection of atomic hydrogen coming from the impact sites,” Retherford said. “This is our first detection of native hydrogen atoms from the lunar environment.”

This video shows LRO as it flies over the north pole of the Moon, where it has a very good view of the GRAIL impact. The second part is the view from LRO through LAMP’s slit, showing the impact and the resulting plume. The orbits, impact locations, terrain, LAMP field of view, and starfield are accurately rendered.

Retherford said further studies from this will help in determining the processes of how the implantation of solar wind protons on the lunar surface could create the water and hydroxyl that has been recently detected on the lunar surface by other spacecraft and in studies of lunar rocks returned by the Apollo missions.

You can see more images from LRO on the LROC website. Additionally, NASA has now issued a press release about this, too.