Helicopters on Titan

Jason Barnes hesitates to call the upcoming Dragonfly mission to Saturn’s moon Titan a helicopter.

“Dragonfly is a nuclear quadcopter lander,” said Barnes while admitting that it sounds at least a little bit crazy. Barnes, a professor of physics at the University of Idaho and deputy principal investigator for Dragonfly, made a presentation at an online astrobiology colloquium at the University of Washington this week. Dragonfly will search for signs of life, biosignatures, on the distant moon.

Why Titan?

The online colloquium was attended by more than 100

people. This slide compared places with an atmosphere and 

solid surfaces.

Barnes noted there are several good reasons for a mission to Titan. It’s one of just four places in our solar system with both a solid surface and a significant atmosphere—the others being Earth, Venus, and Mars. Titan has important similarities to Earth, especially the pressure and composition of its atmosphere.

“The combination of a thick atmosphere and low gravity make Titan the easiest place to fly in the entire solar system,” Barnes said. He noted that we’ve focused on finding water in the search for life, and there’s lots of water on several of the icy moons of the outer solar system.

“The real reason that Titan among these is the most compelling target, I think, is not the water, it’s the carbon,” Barnes said.

He explained that Titan’s atmosphere is made up of mostly nitrogen, but that it contains about 5 percent methane. Ultraviolet light from the Sun breaks methane molecules down into smaller ones that then recombine into larger complex carbon chains that eventually rain down to the surface of Titan.

“They provide the carbon from which you can potentially build up prebiotic and possibly biotic molecules to start the process of how we think life may have formed on Earth four billion years ago,” Barnes said.

Where to look

Observations from the Cassini mission and its Huygens probe have given us several places to look. There are large dunes of organic material on Titan separated by open areas of the moon’s water-ice crust. The impact crater Selk may have once contained a huge water sea that remained liquid for tens of thousands of years—a great place for life to form. Hopscotching to these various places is how the concept of the mission came about.

“We came upon this solution because we needed mobility to be able to get to both the water ice and organic sediments,” Barnes said. “We call it a rotorcraft relocatable lander because we spend almost all of our time on the ground.”

Indeed, Dragonfly will fly to a new spot only about once every Earth month, using time on the surface of Titan to conduct a battery of experiments. One of the mission’s main goals is finding chemical biosignatures. Barnes figures it will be the first mission with such a specific goal since the Viking landings on Mars. He added that there won’t be a rush to judgement on the question of life.

“There’s no silver bullet when it comes to looking for biology,” Barnes said, adding that no single indicator will make them declare they found it. “This is going to be a long, scientific process by which we put in multiple lines of evidence to try to see if we can figure out what’s going on.”

A big spacecraft

Dragonfly will be about two or three meters tall, about three and a half meters long, and weigh about half a ton. It will carry four instruments: a camera suite with eight cameras in all, a mass spectrometer, a gamma ray/neutron spectrometer, and environmental monitoring systems including a seismometer.

The launch of Dragonfly is set for 2026, and it will take about eight and a half years for the craft to get to Titan.

“Exploration of the outer solar system is a process for the patient,” Barnes said.

###

Watch Barnes’s entire presentation:

International Dark Sky Week April 19-26

International Dark Sky Week is coming around at just the right time.

The weeklong (April 19-26) celebration of the night is supported by the International Dark-Sky Association (IDA). It is an opportunity for us all to consider the role of the night and its star-filled sky in each of our lives. This year, IDA is encouraging people around the world to come together online to celebrate the night and engage with authors, creators, scientists, and educators whose works have been vital to the movement to protect the night from light pollution.

“Right now, families around the globe find themselves spending many hours at home together,” notes Ruskin Hartley, IDA’s executive director. “It’s a perfect time to reconnect with the night sky — and International Dark-Sky Week provides a portal for that experience.”

The week includes online presentations by a couple of authors that we have featured in the past on Seattle Astronomy. Paul Bogard wrote one of our favorite books, The End of Night: Searching for Natural Darkness in an Age of Artificial Light (Little, Brown and Company, 2013). Bogard will do a reading from the book Tuesday, April 21. Tyler Nordgren, a professor of physics and an artist, will do a talk about the role of art in conversation on Monday, April 20. Nordgren has created a series of great solar system travel posters and is the author of Sun Moon Earth: The History of Solar Eclipses from Omens of Doom to Einstein and Exoplanets (Basic Books, 2016). Jeffrey Bennett, author of What Is Relativity?: An Intuitive Introduction to Einstein’s Ideas, and Why They Matter (Columbia University Press, 2014), will give a presentation called “I, Humanity” on Sunday, April 19. It is geared toward kids in grades five through seven.

There will be numerous other presentations about various astronomical topics. You can access the full schedule online, but beware that it isn’t particularly user friendly, and specific times for most of the presentations have not yet been set as of this writing.



Further reading:

• Our review of Sun, Moon, Earth
• Coverage of Nordgren’s talk at Town Hall Seattle in 2017
• Coverage of Nordgren’s talk at the Seattle Astronomical Society 2014 banquet
• Post about Bogard’s 2013 talk at Town Hall Seattle
• Coverage of Bennett’s 2015 talk at the Seattle Astronomical Society

Pink supermoon

I always note that I’m not really an astrophotographer, and this is readily apparent to anyone who sees my shots, but I do occasionally like to take a snap just to prove I was there. Thus, here’s my photo of the full Moon of April 7, 2020.

There are those who call this the pink Moon, even though it isn’t pink, and a supermoon, which may be an exaggeration even though the Moon is excellent. I’ve read a few sources this morning claiming that we “often” call the April full Moon the “Grass Moon” or the “Egg Moon.” This may well depend on just how you define often.

The super bit comes from the fact that this particular Moon does appear to be slightly larger in the sky–about seven percent bigger than the average full Moon. That’s because the moment of fullness came when the Moon was near perigee, its closest point to Earth during its orbit around us.

For those into photo specs, I made this with a simple Canon PowerShot A530 pointed through the eyepiece of my 8-inch Dobsonian at 50x magnification.

The Moon will be pretty close to full this evening and almost as super, so check it out if you can.

Open houses on hold at Jacobsen Observatory

Photo: Greg Scheiderer

The first of this year’s semimonthly open houses at the Theodor Jacobsen Observatory on the University of Washington’s Seattle campus was scheduled for today. Like many events, the series has been halted by our “Stay Home, Stay Healthy” response to the coronavirus pandemic.

In normal years the events are held on the first and third Tuesdays of each month from April through September, but the observatory’s website notes that the open houses “are suspended until all classes are being held in their regular classrooms and our undergraduate volunteers are back on campus.” Undergrads give talks about astronomy at the events, and volunteers from the Seattle Astronomical Society staff the observatory’s vintage 1892 telescope, which features a 6-inch Brashear objective lens on a Warner & Swasey equatorial mount.

The website notes that organizers hope to welcome students back and to resume the open house series “soon.”

Watch this space for updates.

Summer astronomy from home

Yesterday I did an interview with a writer who is working on an article for a regional travel magazine. Its editors have concluded that most folks aren’t so anxious to go anywhere right now given our situation with coronavirus and stay-at-home orders. They correctly note that astronomy is something that one can enjoy without venturing too far afield.

It’s true! The sky is everywhere. All you have to do is look up! There are lots of interesting things to see that don’t even require a telescope or binoculars. Here’s a quick look at just a few of the things headed our way this spring and summer.

Venus 

Venus is the queen of the evening hours these days and is high in the west at dusk. She’s flirting with the Pleiades, the Seven Sisters, and will be closest to this gorgeous star cluster tomorrow, April 3. The Sun will set around 7:40 p.m. Pacific time. Give it until a little after eight for the Pleiades to appear, then they and Venus will hang out together until they all set a bit after 11 o’clock. If you have binoculars or a telescope take a closer look to spot the phase of Venus. It’s a pretty thin crescent right now. The Pleiades look great through binoculars, too!

Comet ATLAS 

Discovered in December, the comet ATLAS, so-named because it was first spotted by astronomers using the Asteroid Terrestrial-impact Last Alert System in Hawaii, has some folks thinking it may become a highly visible naked-eye object, perhaps the best in 20 years. Comets can be pretty fickle, and such predictions are often the kiss of death. But it doesn’t cost anything to keep an eye out.

This article from EarthSky explains how to find ATLAS. If it’s going to be spectacular, that will happen later this month through most of May. Maybe.

Parade of planets 

Your view of Jupiter from your back yard won’t be
quite as great as the 2016 Hubble Space
Telescope photo. Credits: NASA, ESA, and
J. Nichols (University of Leicester)

Mars, Jupiter, and Saturn are keeping pretty close company in the pre-dawn sky these days. You can spot all three low in the southeast after about 4:15 a.m. when Mars rises, the last of the trio to peek above the horizon. Mars will appear to move east of the others in the coming weeks and months, but Jupiter and Saturn will stay pretty close together all summer. They reach opposition on July 14 and July 20, respectively. Mars reaches opposition on October 13, and this year’s apparition of the Red Planet will be a good one. They aren’t great naked-eye targets, but Neptune will be at opposition on September 11 and Uranus will be opposite the Sun on Halloween.

Meteor showers 

The Perseid is probably the most well-known of the annual meteor showers. Maybe that’s because it’s pretty consistent and happens in the summer when folks don’t mind being outside in the evening. This year’s peak will occur around August 11-12. The last quarter Moon will brighten the sky somewhat at that time, making some of the dimmer meteors difficult or impossible to spot. While you can catch many of the brighter meteors even from light-polluted cities, the darker the sky you have, the better the show. The Lyrid meteor shower peaks around April 22 and the Eta Aquarids May 5. EarthSky has a full rundown of the year’s meteor showers.

Keep looking up!