As of today all new content on Seattle Astronomy will be posted there. We’ve migrated most of our material from the last 9+ years over to that URL as well. We’ve decided to discontinue our “Astro Biz” feature and so have not moved those posts, nor have we brought over numerous “upcoming events” posts that are no longer relevant and don’t seem to have any evergreen value.
As of now we plan to maintain our astronomy events calendar–though few events are occurring these days–as well as our maps to stargazing sites.
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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.
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.
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.”
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.
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.
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.”
Astronomy events are few and far between these days as clubs cope with stay-at-home restrictions and institutional closures in response to the coronavirus pandemic. Most meetings and public star parties have been canceled for March and April while a few wait to see how events unfold.
McLaren gave a quick history of Mars exploration, from Mariner 4 which sent 21 photos back from Mars after a fly by in 1965 to the present work of Curiosity. He noted that Viking 1 in 1976 sent back the first photo from the surface of Mars. It was no accident that it shot its own foot.
“If we can only get one picture back, this is the most important picture, because they want to see how well the landing gear performed,” McLaren explained. “If they can see how the landing gear did, it gives them an idea of how they can improve the next lander.”
Unfortunately, experiments conducted by Viking were thought to rule out the possibility of life on Mars, though McLaren noted that there’s still some discussion about whether those experiments were conducted and interpreted properly. In any event, the zeal for Mars exploration cooled somewhat until the mid-1990s, when a Mars meteor discovered on Earth was found to contain what could be fossilized bacteria. This sparked new scientific interest in the Red Planet.
We returned to the surface of Mars in 1997 with Sojourner and Pathfinder, which proved we could land and drive around a rover on Mars.
“It truly was the Pathfinder that led us to design more sophisticated vehicles,” McLaren said. Spirit and Opportunity followed in 2004 and Curiosity landed in 2012.
Same car, new features
Perseverance, known as Mars 2020 until a recently concluded naming contest, will be something of a souped-up version of Curiosity. It’s based on the same design, but they’ve re-engineered the wheels, as those on Curiosity showed heavy wear unexpectedly early in its mission. Perseverance will also carry different instruments more specialized for astrobiology and geology. It will drill core samples and leave them cached on Mars awaiting a possible future return mission. And its cameras in general are more powerful and versatile than those of Curiosity. It’s mission is different, too. While Spirit and Opportunity were sent to follow the water and Curiosity is trying to figure out if Mars could have supported microbial life, Perseverance will actually be looking for evidence of that life.
A big challenge for the engineers will be delivering Perseverance to its landing site, which is in a crater called Jezero on the edge of what appears to have once been a lowland sea. There’s what looks like a former river delta on the edge of Jezero crater.
“The hope is that water was here for a long time, water flowed down here building this silt, that this is the most likely location where they hope to find any signs of life,” McLaren said.
A small target
The challenge is that the landing ellipse, the target they need to hit, is ten times smaller by area than that of Curiosity and some 300 times smaller than Pathfinder’s. They’ll used a technologically enhanced version of the sky crane technique that worked for Curiosity to try to hit that target.
The window for a possible launch opens on July 17 this year and McLaren said NASA expects to land Perseverance on Mars on February 18, 2021.
Many businesses, products, and places have names rooted in space and astronomy. We’re featuring one periodically on Seattle Astronomy.
Today’s Astro Biz is Mercury Fitness, a Kenmore, Wash.-based firm that does repair and maintenance of exercise equipment. I love their slogan, “We keep you running,” even though it reminds me of Michael McDonald, who ruined the Doobie Brothers. I spotted the Mercury Fitness van at the West Seattle Health Club when I arrived for a recent workout. The Mercury guys were working on one of the club’s elliptical machines.
It still raises eyebrows among people who know me when I mention being “at the gym.” My wife and I both started working out last year as part of our routine to be more fit. I don’t use the ellipticals, but I’m glad Mercury is there to fix them!