Vintage Voyager: Online Video Resources

by | Sep 22, 2017 | Missions | 20 comments

With Voyager on my mind because of its recent anniversary, I had been exploring the Internet landscape for archival footage. But Ioannis Kokkinidis made my search unnecessary with the following essay, which links to abundant resources. The author of several Centauri Dreams posts including Agriculture on Other Worlds, Ioannis holds a Master of Science in Agricultural Engineering from the Department of Natural Resources Management and Agricultural Engineering of the Agricultural University of Athens. He went on to obtain a Mastère Spécialisé Systèmes d’informations localisées pour l’aménagement des territoires (SILAT) from AgroParisTech and AgroMontpellier and a PhD in Geospatial and Environmental Analysis from Virginia Tech. Now a resident of Fresno CA, Ioannis tells us in addition how a lifelong interest in space exploration was fed by the Voyager mission and its continuing data return. 

by Ioannis Kokkinidis

Introduction

Back in the end of August 1989, when I was 9 ½ years old and the whole family was on vacation, the Greek press set aside momentarily its coverage of the continuing shenanigans of Greek politics and the rapidly changing situation to the north of our borders due to the collapse of communism and instead put Voyager 2’s encounter with Neptune in its front pages. My late grandfather was an avid reader of newspapers, which I would also read afterwards. I devoured what I could get my hands on, which alas was not much, it was after all August.

The next year my family moved to California for two years, my father was a visiting professor at UCSF, and I read all the books and magazines about space I could find in the public libraries. I even discovered NASA’s Spacelink, a NASA public education computer service hosted by the Marshall Space Flight Center in Alabama, containing mostly NASA press releases, and I would dial in with our PC XT’s 2400 bps modem. However feeding my space interest was a privilege and my parents made me do a thing I truly dreaded in exchange for dialing the long distance number and indulging myself: play the piano.

After we returned to Greece keeping myself appraised of the latest space developments proved difficult since there is very little popular scientific press in Greece and the mainstream press is not that interested in space. When I got our first internet connection NASA’s Spacelink, now a website, was still up, it still had similar content, though more importantly the releases now included in the bottom instructions on how to get on NASA’s press listserv. I promptly signed up, and I still am on that listerv, becoming informed of the latest space developments, especially in an era before the current proliferation of internet space media made it possible to get the latest space news whenever you wish.

Space in general and NASA in particular have been trailblazers in the formation of the current internet media landscape. Early internet users were for the most part technically savvy people with a strong interest in space. When Mars Pathfinder landed in 1997 it became the first major mass internet event with some 200 million hits on its website, at a time when the internet is believed to have had fewer than 500 million internet users worldwide. Space enthusiasts have always had interest that the mainstream media would not quite satisfy and NASA has indulged those interested, posting pictures, press releases and blogs online, up to the point that today the press conferences are open to all and NASA takes questions from the public in social media.

The ability to consume the latest information about space today runs the whole specter, from basic articles intended for children to conference and peer review papers for professionals, which amateurs can also try to parse for meaning. This was not the case though during the planetary phase of the Voyager program. Per the Voyager books and documentaries I have seen over the years the Jet Propulsion Laboratory held a series of daily press conferences during encounter times that apparently were taped, footage of them is shown in said documentaries. Being on the 40th anniversary of the launch of the most successful planetary missions, I wondered if any of that content was available online. I have discovered that quite a bit was, especially of the 1989 Neptune encounter. When I asked online I was also told, and I did discover, that JPL also produced on a daily basis, and at times more often, 10-15 minute Voyager update videos intended for a general public that were apparently broadcast on PBS, in addition to being shown at Planetariums and science centers. I was able to also find several of these videos are available online too. To my surprise very little of this content is uploaded from official NASA accounts, rather it has been uploaded and collected by enthusiasts.

Image: Some documentaries mixed actual footage with artist’s renderings of the landscapes Voyager saw. This image is from a 1982 NASA presentation.

Understanding the origin of the content

NASA does have quite a bit of Voyager data and information up on its website. It still has the original press kits up, which I actually read them back when I dialed up at Spacelink. The scientific information collected is available for all at the Planetary Data System. Voyager has a website up, with a lot of retrospective information. There are several Von Karman lectures up on YouTube, as are press conferences organized both by NASA but also scientific societies such as the AGU. However these mostly date from the last 15 or so years, especially after YouTube was created. The older stuff has been put up by other people. Having watched the stuff and lived a few years both as a child and as an adult I have a few hunches on who is responsible for doing this public service. One needs first to understand how the education system works in the US.

In Greece primary and secondary education is highly centralized. The Ministry of Education in Athens decides what is to be taught in each grade, each class syllabus and even sends the school books and teachers to the public schools. In private schools the owners select their teachers, but the curriculum and books is the same as in public schools. For that matter the graduating exams at the end of the year there are given by public schools teachers to ensure that private schools are not places where bad students go to buy an education certificate. Students and parents have no control over what gets taught up to high school where some choice is introduced, except of course by their vote in the parliamentary elections, or even who teaches it, except by pressuring their local Members of Parliament. Physics teachers – who in Greece are all physicists graduates of four year universities – have no reason to entice students to take their class, the students are obligated to do so. Greeks schools are also seriously lacking in means, before an EU program about a decade ago only about 150 schools out of the 20,000+ that then existed in Greece had a school library, and though with EU funding and school mergers due to the financial crisis some 10-20% of schools now have a library, that is still a small fraction.

The American educational system is far more decentralized but also has more means. The federal Department of Education can set some guidelines and offer grants, but the educational standards are set at the state level. Major decisions such as hiring and school book choices are made at the school district level, with the school district being made up of representatives directly elected locally, rather than ministry of education centrally appointed functionaries. Now down at the school level students have quite a bit of class choice. As a result science teachers need to make their classes appealing to students in order to have them select it. One way to do so is to teach about cool things in class, and space is generally considered very cool. As a result teachers and schools have maintained such cool content like NASA produced educational material. Also American schools have many means not available to Greek schools, such as school libraries that can include a media section with such material. On top of that some 10% or so of American students are home schooled by their parents, and they often use such material to teach science class. Materials on the internet get copied around incessantly so it hard to track who is the original uploader, but after watching quite a bit of the material shown below I am under the impression that most of the videos have been originally taped by some science teacher or librarian, who eventually uploaded them online.

Jupiter encounters

Voyagers 1 and 2 encountered Jupiter back in 1979. Sony’s Betamax was released in 1974, VHS was released in 1977, there are testimonials on the internet of people watching the Voyager Jupiter updates as children every night on TV but if people recorded the updates at the time, they have not put them up, and neither has NASA. What I have been able to find is the following 24 minute video dating from 1982 that talks about the Voyager 1 and 2 encounters at both Jupiter and Saturn. The first 14 minutes are about Jupiter, the rest is about Saturn.

Image: Io’s volcanoes discussed in this 1982 broadcast.

https://www.youtube.com/watch?v=XAFXQ_EeyGs

Saturn encounters

Voyager 1 encountered Saturn in November 1980 and Voyager 2 in August 1981. We do not have online any of the daily press conferences or full Voyager updates; we do have though two educational documentaries from the time that include extended footage from them. In both cases they are of Voyager 2’s encounter with Saturn. Why Voyager 1’s encounter is not shown is unknown to me, but my guess is that these videos where shown in the run up to the 1986 Voyager 2 encounter with Uranus, and thus the idea was to show what Voyager 2 did in its last encounter. Both videos come from collectors of archival documentary footage on YouTube.

NASA Voyager 2 Spacecraft: Encounter with Saturn – 1981 Educational Documentary

https://www.youtube.com/watch?v=OGZk1SOIQaI

Voyager 2 Saturn Encounter as it Happened 1981 NASA Jet Propulsion Laboratory

https://www.youtube.com/watch?v=CJC4s5kijyU

Uranus Encounter

By 1986 video tapes had become more popular. While we do not have footage of any of the press conferences, we have footage of Voyager updates. This video begins in mid update, and then gives several other updates. It seems to have been recorded by somebody in Arizona, since interspaced among the Voyager Updates a small documentary about the USGS Astrogeology center in Flagstaff which is referred to as a local facility. Notice also the scroll for an upcoming Doctor Who episode.

The Voyager Updates do not only deal with the Voyager program, they also give some more general NASA news. One of the updates give a retrospective on how 1977 when the Voyagers were launched Jimmy Carter was just sworn President and the Shah was still ruling Iran. Another updates talks about the upcoming 1986 launches of the Shuttle that will see Galileo, Ulysses and the Hubble Space Telescope get launched. Tragically, Challenger happened two days after Uranus closest approach.

https://www.youtube.com/watch?v=lnijUsIdxSc

Another interesting contemporary program from the time to watch is the Uranus episode of the long running BBC astronomy program The Sky At Night. The BBC has digitized its archive, though the link that YouTube gave me is not from a BBC account:

https://www.youtube.com/watch?v=hUriyE4sGd4

Neptune encounter

The Neptune encounter is far better documented than any of the previous five flybys. Its August timing, which meant that there was very little competing for attention, the experience over the excitement of the previous encounters and the ubiquity of video tapes means that there is quite a bit of material available. The first video is a preview press conference made three months before closest approach, with Ed Stone mostly recapping the previous flybys and explaining to the press new findings since published. In the end he also shows early Neptune pictures taken at the time:

https://www.youtube.com/watch?v=I4io958_BBo

Image: Imagery shown by Ed Stone at the 1989 press conference on Voyager’s encounter with Neptune. Stone used these to explain what would happen in the upcoming encounter.

The following two videos, which appeared as YouTube suggestions after I had seen the rest of the material, purport to contain all the Voyager Updates of the Neptune encounter. They are over twelve hours, so I have only given them a cursory look:

https://www.youtube.com/watch?v=xkUmzPbqJVU

https://www.youtube.com/watch?v=CttozUMkEBA

CSPAN is the American equivalent of Parliament TV. Like Parliament TV it carries educational programs when Congress in not in session. Their oldest video tagged “Space” was a hearing on the Challenger disaster. They do not have Voyage briefings at Jupiter, Saturn or Uranus but they did show most of the Neptune press briefings. They also had an audience Q&A with the director of NASA’s planetary division, William Quaide on August 24, a few hours before Neptune closest approach. Interestingly most of the press conferences are not all the way to the end, CSPAN apparently cut coverage when they went over their allotted time.

August 21 1989 Voyager 2 Update

https://www.c-span.org/video/?8803-1/voyager-2-update

August 22 1989 Voyager 2 Update

https://www.c-span.org/video/?8812-1/voyager-2

August 23 1989 Voyager 2 Update

https://www.c-span.org/video/?8817-1/voyager-2-update

August 24 1989 Voyager 2 Update

https://www.c-span.org/video/?8855-1/voyager-2-update

CSPAN August 24 viewer call in with NASA chief scientist William Quaide on Voyager 2 at Neptune

https://www.c-span.org/video/?8857-1/voyager-ii-neptune

August 25 1989 Voyager 2 Update

https://www.c-span.org/video/?8864-1/voyager-2-flyby-neptune

On the evening of August 24 to August 25 PBS showed a program called “Neptune all Night” where they showed the hourly Voyager updates live and filled the time in between by having a panel in Philadelphia made of the host, a sci fi writer and a NASA scientist. They also had several guests, such as legendary Hollywood sci fi movie producer and several space scientists such as Jill Tarter. On top of that they did take several questions that were dialed in from all over the US. We do not see any of the panelists or guests, between the updates we have the panelists talking while television is showing Voyager animations such as flyovers of satellites or even Space Shuttle astronauts doing things in space. Two people did tape the program beginning at different points. The first video is from a Florida station and it is of middling quality. It is over five hours:

https://www.youtube.com/watch?v=VBR5OUtndg8

The second video is from New York’s PBS 13 and contains far more ads to become a subscriber to PBS than the previous video, or the Arizona PBS Uranus video. The tape is of higher quality, but in begins at the equivalent of the 4h 34 minutes mark from the previous video.

https://www.youtube.com/watch?v=G84w-z6LkDo

The two hour tape ended before the program did, a little after the 3 am Voyager Update. However NASA solar system exploration has put up the last three Voyager Updates of the morning of August 25, for 5 am, 6 am and 7 am in a YouTube video entitled “Voyager 2 at Neptune with Suzy Dodd”. Suzanne Dodd is the current Voyager project manager and she does host the 5 am and 6 am update, though not the 7 am update. At 8 am there was no update, instead Vice President Dan Quayle gave a speech that CSPAN has at its archives in two parts. The Suzy Dodd video is in much better image quality that the rest of the Voyager videos, either at YouTube or CSPAN. Very likely NASA still has the original videos in its archives and at much higher quality than what I found online.

https://www.youtube.com/watch?v=AR_R5mFk9Tc

The Neptune encounter was big enough news that several mainstream media organizations made special reports about it. These YouTube videos do not come from the official station accounts. The first is a CNN special report on the Neptune encounter.

https://www.youtube.com/watch?v=Y11CVuxfvPE

The second special was made by TBS and contains reporting from Japan, which did participate in the Neptune and Triton Voyager occultation. It is hosted by Sidney Poitier and is available in 8 parts. The 8th part contains Chuck Berry playing live three songs at the Planetary Society’s farewell party.

Part 1 of 8

https://www.youtube.com/watch?v=y038-R3kwfw

Part 2 of 8

https://www.youtube.com/watch?v=gKVnzfiw1ac

Part 3 of 8

https://www.youtube.com/watch?v=c8eqYVFgzIU&t=5s

Part 4 of 8

https://www.youtube.com/watch?v=KPVwM7ikI4E

Part 5 of 8

https://www.youtube.com/watch?v=k7e1NDj-v0o

Part 6 of 8

https://www.youtube.com/watch?v=oKfVo_r4q7M

Part 7 of 8

https://www.youtube.com/watch?v=w8Uw1_Rad6Y

Part 8 of 8

https://www.youtube.com/watch?v=2adIOstO51g

Finally Sir Patrick Moore, who most likely was not knighted yet at the time, hosted a Neptune encounter episode for The Sky At Night. This program is far more complete and interesting, in my opinion, than the two other specials.

https://www.youtube.com/watch?v=H9UdqHL6b9Y

The Pale Blue Dot Press Conference

On June 6 1990 Ed Stone and Carl Sagan gave a press conference that for the most part summarized what the Voyagers had found during their planetary mission and revealed to the world the family portrait of the Solar System that Voyager 1 took. It was in this press conference that the famed Pale Blue Dot single pixel image of Earth was revealed. For the first 40 or so minutes Ed Stone gives a retrospective of Voyager, repeating for the most part what he had said a year earlier in the three months before Neptune press conference. He also though gives a few scientific updates on Neptune. After 40 minutes he shows the family portrait of the 6 planets, followed by Carl Sagan talking for 10 minutes on the portrait, followed by 30 minutes of Q&A.

https://www.youtube.com/watch?v=ZQCTgCF8Khk

The videos in retrospective

Over a quarter of a century since the Pale Blue Dot press conference the more interesting part about these videos is what they reveal about the time they were produced. In the Neptune press conferences the Voyager team fielded questions from West German reporters, the Wall after all fell in October 1989 and Germany was reunified in 1990. Carl Sagan proposes that we have a Joint US Soviet program to send people to Mars, the collapse of the Soviet Union was completely unexpected for everyone. Viewers tend to ask the same questions: Why is Voyager 2 not going to Pluto? Why did Voyager 1 not also visit Uranus and Neptune? Why did you choose Triton over Pluto? Did you find any evidence of alien life, preferably intelligent? When are we sending people to Mars? Did you find evidence of a wormhole, like in Star Trek The Motion Picture? Can you talk about the Golden Record?

The Voyager team does promote the next steps: We will use Hubble Space Telescope images, after its upcoming launch, to follow up on Uranus and Neptune. Galileo to Jupiter is about to launch, and we have proposed Cassini and CRAF as follow up, if Congress approves the missions. Magellan was launched 6 months ago, the long launch gap is over, and it was due to the Challenger disaster. With the power of hindsight we can follow up. Magellan has been called Voyager 3 because it followed its engineering. It was very successful but it is alas the most recent American mission to Venus. Galileo was also a successful mission but suffered from being unable to unfurl its High Gain Antenna. Cassini was approved, and its mission just ended. CRAF though, which intended to flyby an asteroid and orbit a comet on which it would throw a projectile was cancelled. Its science goals though were investigated by Stardust, Deep Impact and Rosetta.

Voyager afterwards

The Voyager program did not end with the Solar System family portrait, for that matter it was not even the last images taken by the imaging subsystem. At the time both Voyagers were used as astronomical observatories, targeting stellar sources in the Ultraviolet. A few months later though they rewrote the spacecraft’s operating system and turned off all the instruments except those measuring fields and particles. During the Shoemaker Levy 9 collision NASA considered reactivating the imaging system to take pictures of the event which was not visible from earth. By that time though the imaging team had dispersed and it was hard to reassemble it. In any case Galileo, en route to Jupiter, took better images. From the Jupiter video already it was repeatedly stated that their last target was the edge of the heliosphere. In the Jupiter video Ed Stones expects that to happen by the end of the century, in the Pale Blue Dot conference he expected that in the first decade of the 21st century.

Throughout the 1990s I would read on any updates on the Voyagers sent by the NASA listserv. Most often they were associated with launch anniversaries or lectures at the fall AGU meeting in San Francisco. Both spacecraft did keep on moving outwards into unexplored part of the heliosphere. Voyager 1 crossed the termination shock at 94 AU in December 2004 and Voyager 2 crossed it at 84 AU in August 2007, entering the heliosheath, where the solar wind is subsonic. Where it ended and the Galactic magnetic field started was a point of contention, especially since the plasma spectrometer on Voyager 1, though not Voyager 2, has failed. In 2012 Voyager 1 did see a dramatic increase in external galactic cosmic rays as opposed solar particles, but we were not certain if the spacecraft had crossed into interstellar space because the magnetic field had not changed direction. Eventually though tape playback of the plasma wave instrument data showed that indeed, in 2012, Voyager 1 had crossed the heliopause and was now in the Galactic magnetic field. Voyager 2 has yet to cross the heliopause though that is expected to happen relatively soon.

Image: Voyager moving beyond the Solar System. Credit: NASA.

The Golden Record

It seems that no Voyager article or documentary is complete with talking about the Golden Record and so will I. In all honesty I always found the pictures taken by the Voyagers more interesting than the record. The artifact is intended to be read by aliens who might run into the probes and contains instructions on how to use it. The instructions assume that the aliens are capable of interpreting the visual signs that we have put up sufficiently to decode the contents of the record. This is a very large assumption considering we have no idea what aliens can do and how. For one thing over a century after their discovery, Linear A tablets have never been deciphered. We believe that like Linear B tablets, which are written in Greek, they are accounting ledgers from the Minoan palaces where they were found, but until we read them we cannot be sure. On top of that the Voyager symbols are written in unique characters. The Phaistos Disc is written in a unique script, closest relative of which is the Arkalohori Axe. Wikipedia lists 26 decipherment claims for the Phaistos Disc which remain fanciful since we cannot apply them to another text to see if they make sense there. Michael Ventris’ decipherment of Linear B became accepted after it was used to read tablets that were published after he and John Chadwick published his discovery. Perhaps it would have been better if we had also printed instructions in English.

But say that alien do read the record, which contains both images and sounds coded differently. On top of that the human speech is in 55 languages. Much as Sagan and Druyan did try to give a snapshot of all human civilization, it is very hard to claim that it is an objective view of mankind. None of the contents, either images or songs, deal with war or any other ugly part of humanity. Trying to understand human civilization from the Golden record is like trying to understand Athens of the Classical Era from Pericles’ Funeral Oration: Both are wonderful documents but they portray their world as they wish it to be, rather than what it is. Still though they tell us quite a bit about ourselves and it was a great idea to include the Golden Record on the spacecraft. I sincerely hope that the project to write a repository of Earth Information on New Horizons does happen.

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New Horizons After 2014 MU69

by | Sep 21, 2017 | Outer Solar System | 13 comments

If New Horizons can make its flyby of Kuiper Belt Object MU69 at a scant 3500 kilometers, our imagery and other data should be much enhanced over the alternative 10,000 kilometer distance, one being kept in reserve in case pre-encounter observations indicate a substantial debris field or other problems close to the object. But both trajectories, according to principal investigator Alan Stern, have been moved closer following a ten-week study period, and both are closer than the 12,500 kilometers the spacecraft maintained in its flyby of Pluto.

Image: Artist’s concept of Kuiper Belt object 2014 MU69, which is the next flyby target for NASA’s New Horizons mission. Scientists speculate that the Kuiper Belt object could be a single body (above) with a large chunk taken out of it, or two bodies that are close together or even touching. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker.

Stern made the statement in early September at a meeting of the Outer Planets Assessment Group (OPAG), in which he also pointed out that flyby observations of the distant KBO will commence in August of next year in preparation for the early January arrival in 2019. The process of returning acquired data to Earth is estimated to take up to 20 months.

We also get this heartening news: Stern considers the Kuiper Extended Mission of New Horizons to be ‘multi-pronged,’ with the January 1 flyby of MU69 perhaps the prelude to further operations. New Horizons has sufficient fuel and power to operate until roughly 2035, and the downlink of MU69 data will end in September of 2020. The current extended mission was approved for the period 2016-2021. Will there be another?

According to Stern’s presentation at OPAG, the current extension involves not just the flyby of MU69, along with heliospheric plasma, dust, and neutral gas observations in the Kuiper Belt, but also distant observations of up to 30 other KBOs and numerous Centaurs. These studies involve searches for satellites, rings and dust along with examination of KBO light curves and shapes, with numerous papers on these results said to be in early stages of preparation.

With enough power and fuel to make it well into the 2030s, New Horizons, which is after all the only spacecraft with the opportunity to make these observations, could continue its active work for many years. An extended mission from 2021 to 2024 would allow additional KBO flyby search time for future targets as well as continuing Kuiper Belt observations.

And on the question of what happens after New Horizons, Stern’s presentation at OPAG included the possibility of a Pluto orbiter, which is already being studied at SwRI, Ball Aerospace, Lockheed-Martin and NASA GSFC. A tantalizing thought, that.

Jeff Foust quotes Stern in The Space Review as saying this:

“I think New Horizons has a bright future, continuing to do planetary science and other applications. There’s fuel and power onboard the spacecraft to operate it for another 20 years. That’s not going to be a concern even for a third or fourth extended mission.”

Image: Flight controllers (from left) Katie Bechtold, Ed Colwell and Jon Van Eck, working in the mission operations center at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, confirm data indicating that the New Horizons spacecraft had safely exited hibernation on Sept. 11, 2017. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Meanwhile, New Horizons ‘awakened’ from a five-month hibernation period on September 11, being brought over the next three days into active mode, in which science instrument checkouts and data collection activities can resume, to be continued until mid-December. From the latest JHU/APL news update outlining the course of the coming months:

The spacecraft will train its instruments on numerous distant KBOs, making long-distance observations with the telescopic Long Range Reconnaissance Imager (LORRI), while also continuously measuring the Kuiper Belt’s radiation, dust, and gas environment. The team also will test the spacecraft’s instruments in preparation for next year’s approach to MU69, and transmit a new suite of fault-protection software – also known as autonomy software – to New Horizons’ computer in early October.

On December 22, New Horizons again goes into hibernation, to be awakened on June 4, 2018, at which point preparations for the MU69 approach will go into high gear. The spacecraft is currently 3.89 astronomical units (AU) from MU69 as Kuiper Belt exploration continues.

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A Fleet of Sail-driven Asteroid Probes

by | Sep 20, 2017 | Outer Solar System | 15 comments

One of the great values of the Kepler mission has been its ability to produce a statistical sample that we can use to analyze the distribution of planets. The population of asteroids in our own Solar System doubtless deserves the same treatment, given its importance in future asteroid mining as well as planetary protection. But when it comes to main belt asteroids, we’re able to look up close, even though the number of actual missions thus far has been small.

Thus it’s heartening to see Pekka Janhunen (Finnish Meteorological Institute), long a champion of intriguing ‘electric sail’ concepts, looking into how we might produce just such an asteroid sampling through a fleet of small spacecraft.

“Asteroids are very diverse and, to date, we’ve only seen a small number at close range. To understand them better, we need to study a large number in situ. The only way to do this affordably is by using small spacecraft,” says Janhunen.

The concept weds electric sails riding the solar wind with a fleet of 50 small spacecraft, the intent being that each should visit six or seven asteroids, collecting spectroscopic data on their composition and taking images. Dr. Janhunen presented the idea at the European Planetary Science Congress (EPSC) 2017 in Riga on Tuesday September 19.

Image: The single-tether E-sail spacecraft. Credit: Janhunen et al.

Electric sails ride the solar wind, that stream of charged particles that flows constantly out of the Sun. While solar sails take advantage of the momentum imparted by photons on the sail, and beamed energy sails are driven by microwave or laser emissions, electric sails use the solar wind’s charged particles to generate all the propulsion they need without propellant. What Janhunen envisions is a tether attached to one end of a spacecraft, to which is attached an electron emitter and a high-voltage source, all connected to a remote unit at the other end.

The tether makes a complete rotation every 50 minutes, creating a shallow cone around a center of mass close to the primary spacecraft. Each small craft can change its orientation to the solar wind, and thereby alter its thrust and direction. Janhunen’s presentation at the EPSC made the case that a 5 kg spacecraft with a 20 kilometer tether could accelerate at 1 millimeter per second squared at the Earth’s distance from the Sun. Coupled with the boost provided by the launch itself, this is enough to complete a tour through the asteroid belt and return within 3.2 years.

Image: Artist’s concept of the spacecraft. Credit: FMI.

These spacecraft are small enough (Janhunen refers to them as ‘nanosats’) that they cannot carry a large antenna. Instead, the mission concept calls for each spacecraft to make a final flyby of the Earth to download mission data. The financial numbers are compelling. Billions of Euros would be involved in attempting a flyby of 300 asteroids with conventional methods, while Janhunen’s fleet of nanosats could, he believes, fly this mission for 60 million Euros.

The payoff could be substantial:

“The nanosats could gather a great deal of information about the asteroids they encounter during their tour, including the overall size and shape, whether there are craters on the surface or dust, whether there are any moons, and whether the asteroids are primitive bodies or a rubble pile. They would also gather data on the chemical composition of surface features, such as whether the spectral signature of water is present.”

Working with ever smaller payloads is a recurring theme in deep space exploration, the ultimate example being Breakthrough Starshot’s study of a laser-beamed sail mission to Proxima Centauri’s planet, one that would deploy a fleet of sails just meters to the side, each carrying a payload as small as a microchip. In Janhunen’s concept, the spacecraft are capable of carrying a 4-centimeter telescope capable of resolving asteroid surface features, along with an infrared spectrometer that can analyze reflected light to determine the object’s mineralogy.

With flybys at a range of about 1000 kilometers, the spacecraft would be able to image features to a resolution of 100 meters or better, and with multiple targets for each, the catalog of main belt asteroids that we have seen up close would suddenly mushroom. The mission, being referred to as the Asteroid Touring Nanosat Fleet, would help us catalog the various types of asteroids and provide valuable analysis of their composition and structure, all of which would add to our expertise if and when we ever have to nudge an asteroid into a new trajectory.

200,000 Euros per asteroid is a strikingly efficient use of resources, and the engineering involved in deploying Janhunen’s fleet of electric sails would give us priceless experience as we work with other mission concepts that involve the solar wind. But can we ride a wind as mutable and unpredictable as this one while ensuring the kind of pinpoint navigation we need? Questions like these will need answering in space through the necessary precursors.

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‘Red Edge’ Biomarkers on M-dwarf Planets

by | Sep 19, 2017 | Exoplanetary Science | 16 comments

When we think about the markers of possible life on other worlds, vegetation comes to mind in an interesting way. We’d like to use transit spectroscopy to see biosignatures, gases that have built up in the atmosphere because of ongoing biological activity. But plants using photosynthesis offer us an additional option. They absorb sunlight from the visible part of the spectrum, but not longer-wavelength infrared light. The latter they simply reflect.

What we wind up with is a possible observable for a directly imaged planet, for if you plot the intensity of light against wavelength, you will find a marked drop known as the ‘red edge.’ It shows up when going from longer infrared wavelengths into the visible light region. The red-edge position for Earth’s vegetation is fixed at around 700–760?nm. What we’d like to do is find a way to turn this knowledge into a practical result while looking at exoplanets. Where would we find the red edge on planets circling stars of a different class than our own?

Led by Kenji Takizawa, researchers at the Astrobiology Center (ABC) of National Institutes of Natural Science (NINS) in Japan have taken up the question with regard to M-dwarfs. These stars have lower surface temperatures than the Sun and emit more strongly at near-infrared wavelengths than at visible wavelengths. Assuming vegetation in such an environment evolves to use the most abundant photons for photosynthesis, shouldn’t we expect the red edge to shift accordingly? Perhaps not, argue the authors, as only blue-green light penetrates beyond a few meters of water. Visible light, in other words, may play a larger role than we imagine.

This is a useful study, because we will begin our observations of possible biosignatures on exoplanets around stars like these, using not only upcoming space missions but ground observatories like the European Extremely Large Telescope, the Thirty Meter Telescope, and the Giant Magellan Telescope. The question is, what effect does the radiation of the star itself have on the red edge?

Image: Artist’s impressions of a habitable planet around M-dwarfs (left) and primordial Earth (right). Credit: ABC/NINS.

The authors believe that the first oxygenic phototrophs would have evolved underwater, using light at visible wavelengths. The star AD Leonis (AD Leo), an M-dwarf located 16 light years away, served as their model, with Takizawa and team plugging in a hypothetical planet of Earth’s size and insolation in orbit in the habitable zone there, allowing light conditions on the planet to be estimated and compared with solar irradiation on the Earth. The paper predicts ‘photosynthetic machineries’ that could emerge underwater and on land, and goes on to examine the question of land phototrophs evolving in the direction of infrared use from marine phototrophs that evolved in visible light.

From the paper:

After comparative investigations of light environments on the hypothetical habitable exoplanet around AD Leo and on the Earth, we conclude that two-photon reactions using visible radiation may first evolve in an M-dwarf planet’s ocean as oxygenic phototrophs. Reactions using NIR radiation may then evolve on the land surface. The first oxygenic phototroph is most likely to be established underwater about 10?m or deeper, and may expand its habitat to shallow water after the formation of an ozone layer and/or the cessation of UV emission from the active M-dwarf.

At depths of one meter and less, the authors believe, the abundance of near-infrared radiation may stimulate its evolutionary use, though notice what happened on Earth:

…phototrophs using NIR radiation are exposed to drastically changing light conditions in shallow water, which may be an obstacle to using NIR radiation before land colonization. The formation of the ozone layer on the Earth prior to the emergence of land plants enabled them to quickly colonize the land, safe from the effects of UV. A rapid transition from aquatic algae to land plants was accomplished without a change in the photosynthetic machinery.

Image: Figure 1 from the Takizawa paper. Credit: Takizawa et al.

The authors’ calculations show that green algae can adapt to M-dwarf radiation, though less productively than phototrophs using near-infrared radiation. Indeed:

…oxygenic photosynthesis could be driven by low-energy NIR radiation by improving the redox energy conversion efficiency and/or employing multi-photon reactions.

Thus it is possible that a ‘first wave’ of land plants could exhibit a red-edge position at 700–760?nm, as on the Earth. Using near-infrared radiation underwater would expose phototrophs to strong changes in light intensity and quality when they approach the water’s surface. That makes it more likely that adaptation to near-infrared would occur once on land, where the radiation spectral change is smaller.

To take these possible changes into account, astronomers need to look in a broad range when considering biomarkers on red dwarf planets:

…future missions should prepare to record surface spectra of habitable exoplanets at wavelengths from shorter than 700?nm to longer than 1,100?nm so that they have the capability to address the possibility that the red-edge position may change as the host M-dwarf ages.

The paper is Takizawa et al., “Red-edge position of habitable exoplanets around M-dwarfs,” Scientific Reports 7, No. 7561 (full text).

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WASP-12b: A Low Albedo Planetary Torch

by | Sep 18, 2017 | Exoplanetary Science | 2 comments

Sara Seager often describes the distribution of exoplanets as ‘stochastic,’ meaning subject to statistical analysis but hard to predict. A good thing, then, that Kepler has given us so much statistical data to work with, allowing us to see the range of possible outcomes when stars coalesce and planetary systems emerge around them. We’re not seeing copies of our own Solar System when we explore other stellar systems, but a variegated mix of outcomes.

Thus finding a planet with an albedo as dark as fresh asphalt goes down as yet another curiosity from a universe that yields them in great abundance. The planet is WASP-12b, a ‘hot Jupiter’ of the most extreme kind. Previous work on this heavily studied world has already shown that due to its proximity to its host star, the planet has been stretched into an egg shape, while its day-side temperatures reach 2540 degrees Celsius, or 2810 Kelvin.

94 percent of incoming visible light here is trapped in an atmosphere so hot that clouds cannot form to reflect it. Hydrogen molecules are broken into atomic hydrogen, while alkali metals are ionized. The atmosphere resembles that of a low mass star instead of a planet, composed of atomic hydrogen and helium. Using Hubble’s Space Telescope Imaging Spectrograph, the international team that produced this result, led by Taylor Bell (McGill University), has now measured an albedo of 0.064 at most, two times less reflective than our Moon.

Image: Twice the size of Jupiter, WASP-12b has the unique capability to trap at least 94 percent of the visible starlight falling into its atmosphere. Credit: NASA, ESA, and G. Bacon (STScI).

The planet’s radius is about twice Jupiter’s. The average hot Jupiter will reflect about 40 percent of incoming starlight, making WASP-12b a statistical outlier. But bear in mind that this planet’s proximity to its host star keeps it tidally locked, with one side always facing the star, the other always turned to space. That drops nightside temperatures well over 1000 degrees Celsius cooler, so that molecules can survive, producing possible clouds and hazes in the atmosphere.

Bell notes that the planet, orbiting about 3.2 million kilometers from its star, demonstrates that even among hot Jupiters the range of possibilities is surprisingly large:

“This new Hubble research further demonstrates the vast diversity among the strange population of hot Jupiters,” Bell said. “You can have planets like WASP-12b that are 4,600 degrees Fahrenheit and some that are 2,200 degrees Fahrenheit, and they’re both called hot Jupiters. Past observations of hot Jupiters indicate that the temperature difference between the day and night sides of the planet increases with hotter day sides. This previous research suggests that more heat is being pumped into the day side of the planet, but the processes, such as winds, that carry the heat to the night side of the planet don’t keep up the pace.”

1400 light years away in the constellation Auriga, WASP-12b circles a G-class star not dissimilar to the Sun, in an orbit lasting little more than a day. In addition to Hubble, the Spitzer Space Telescope and the Chandra X-ray Observatory have examined the system. Bell’s work with Hubble’s STIS examined the world by analyzing the combined light of star and transiting planet as WASP-12b passed behind the star. The scientists measured the albedo of WASP-12b at several different wavelengths. The lack of reflected light in the latter observations indicated that the day-side of the planet is absorbing almost all the starlight that falls onto it.

Back to that word ‘stochastic,’ which is reminding us that even when we look at a seemingly well-defined category of planet, our observations can yield wide differences. As the paper notes:

Our results are in stark contrast with those for the much cooler HD 189733b, the only other hot Jupiter with spectrally resolved reflected light observations (Evans et al. 2013); those data showed an increase in albedo with decreasing wavelength. The fact that the first two exoplanets with optical albedo spectra exhibit significant differences demonstrates the importance of spectrally resolved reflected light observations and highlights the great diversity among hot Jupiters.

Notice that reference to another well studied planet, HD 189733b. Results for the latter suggest that the planet has a deep blue color, while Bell’s team has shown that WASP-12b reflects no light at any wavelength. It does, however, emit light because of its high temperature. Think of a red hue, as this HST news release suggests, similar to hot glowing metal.

I might also note how, once again, we have a planetary system far different from our own. In addition to that hot Jupiter, WASP-12b’s host star is orbited by two M-dwarf companions that are bound in a binary system.

The paper is Bell et al., “The Very Low Albedo of WASP-12b from Spectral Eclipse Observations with Hubble,” Astrophysical Journal Letters Vol. 847, No. 1 (20 September 2017). Abstract / preprint.

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