Hello Space Fans and welcome to another edition of Space Fan News.
This week, recent analysis of data from NASA’s Cassini spacecraft uncover evidence for a
possible habitable zone around Saturn’s moon Enceladus; observations from the ALMA
observatory guided by the Dark Energy Survey have have revealed extraordinary details about
a recently discovered far-flung member of our solar system, affectionately called DeeDee;
and a contest for Space Fans everywhere.
This week was a big one if you care about water on other worlds in our solar system.
In addition to a news conference where NASA discussed it’s upcoming Europa Clipper mission,
which I told you about in SFN 198, they also released evidence found by researchers from
the Southwest Research Institute and other places from data taken from the Cassini Spacecraft
during one of its closest and deepest flybys of the Saturnian Moon.
As it flew past Enceladus, the Cassini spacecraft detected hydrogen in the plume of gas and
icy material spraying from a plume on Oct. 28, 2015.
From these and earlier observations scientists have determined that nearly 98 percent of
the gas in the plume is water, about 1 percent is hydrogen and the rest is a mixture of other
molecules including carbon dioxide, methane and ammonia.
The measurement was made using Cassini's Ion and Neutral Mass Spectrometer (INMS) instrument,
which sniffs gases to determine their composition.
INMS was actually designed to sample the upper atmosphere of Saturn's moon Titan.
But when it was flying over Enceladus in 2005, Cassini made a surprising discovery of a towering
plume of icy spray, coming out of hot cracks near the south pole, scientists turned its
detectors toward the small moon.
Cassini wasn't designed to detect signs of life in the Enceladus plume – indeed, scientists
didn't know the plume existed until after the spacecraft arrived at Saturn.
And ever since, we’ve been enthralled by the possibilities of life on this moon of
Saturn.
So the presence of all this hydrogen gas, which could potentially provide a chemical
energy source for life, is pouring into the subsurface ocean of Enceladus from hydrothermal
activity on the seafloor.
And this means that microbes – if there are any – could use it to obtain energy
by combining the hydrogen with carbon dioxide dissolved in the water.
This chemical reaction, known as "methanogenesis" because it produces methane as a byproduct,
is at the root of the tree of life on Earth, and could even have been critical to the origin
of life on our planet.
So while they haven’t found life yet, they have found that there is at least a food source
for any that might be there.
The situation is analogous to hydrothermal vents deep in the Earth’s oceans which emit
hot, mineral-rich fluid, allowing all kinds of unique ecosystems teeming with unusual
creatures to thrive.
Microbes that convert mineral-rich fluid into metabolic energy make these ecosystems possible.
Researchers are saying that the amount of molecular hydrogen they detected is high enough
to support microbes similar to those that live near hydrothermal vents on Earth.
If similar organisms are present in Enceladus, they could ‘burn’ the hydrogen to obtain
energy for chemosynthesis, which could conceivably serve as a foundation for a larger ecosystem.
So it is looking very promising for these moons, both Enceladus around Saturn and Europa
around Jupiter, for harboring some kind of life.
I have mixed feeling about this, as I’ve told you about before.
Finding two independent instances of life in the solar system could be troubling for
our civilization.
Look up The Great Filter to learn more.
Cassini is the gift that just keeps on giving.
Watch for many more announcement like this as the spacecraft completes it Grand Finale
later this year.
I’ll be sure to keep you posted.
Next, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have
revealed extraordinary details about a recently discovered far-flung member of our solar system,
the planetary body 2014 UZ224, also called DeeDee because astronomers got tired of calling
it Distant Dwarf.
DeeDee is the second most distant known trans-Neptunian object (TNO) with a confirmed orbit, and is
surpassed only by the dwarf planet Eris.
Astronomers estimate that there are tens-of-thousands of these icy bodies in the outer solar system
beyond the orbit of Neptune.
DeeDee is pretty far out there, at three times the distance that Pluto is from the Sun and
92 times as far away as the Earth is from the Sun.
The new ALMA data reveal, for the first time, that DeeDee is roughly 635 kilometers across,
or about two-thirds the diameter of the dwarf planet Ceres, the largest member of our asteroid
belt.
Now this is important because at this size, DeeDee should have enough mass to be spherical,
which we’re all coming to learn is the criterion necessary for astronomers to consider it a
dwarf planet, though it has yet to receive that official designation from the International
Astronomical Union.
DeeDee is so far away it takes more than 1,100 years to complete one orbit.
Light from DeeDee takes nearly 13 hours to reach Earth.
Now what I find most interesting about this story is that the ALMA observations were built
on earlier ones from the Dark Energy Survey which actually discovered it, and this is
a sign of the times folks.
We have telescopes looking at huge swaths of the sky for many nights, building up timelapses
of very large and very deep parts of the sky.
These surveys are invaluable when it comes to discovering new things way out in our solar
system.
The Dark Energy Survey looks at 5000 square degrees of sky in the southern hemisphere
and produces vast troves of astronomical images, which give astronomers the opportunity to
also search for distant solar system objects.
The initial search, which includes nearly 15,000 images, identified more than 1.1 billion
candidate objects.
The vast majority of these turned out to be background stars and even more of them were
distant galaxies.
A small fraction, however, were observed to move slowly across the sky over successive
observations, the telltale sign of a TNO.
So this optical data from the 4m telescope in Chile allowed astronomers to get DeeDee’s
distance and orbital properties, but they were unable to determine its size or other
physical characteristics.
It was possible that DeeDee was a relatively small member of our solar system, yet reflective
enough to be detected from Earth.
Or, it could be uncommonly large and dark, reflecting only a tiny portion of the feeble
sunlight that reaches it; both scenarios would produce identical optical data.
And that’s where ALMA saves the day.
Since it is designed to look at cold and dark things, it is able to detect the heat – in
the form of millimeter-wavelength light – emitted naturally by cold objects in space.
The heat signature from a distant solar system object would be directly proportional to its
size.
While the reflected visible light from DeeDee is only about as bright as a candle seen halfway
the distance to the moon, ALMA was able to quickly home in on the planetary body’s
heat signature and measure its brightness in millimeter-wavelength light.
According to these observations, astronomers calculated that DeeDee is only about 30 degrees
Kelvin, just a little above absolute zero.
Objects like DeeDee are cosmic leftovers from the formation of the solar system.
Their orbits and physical properties reveal important details about the formation of planets,
including Earth.
This discovery is also exciting because it shows that it is possible to detect very distant,
slowly moving objects in our own solar system.
The researchers note that these same techniques could be used to detect the hypothesized “Planet
Nine” that may reside far beyond DeeDee and Eris.
Golden age folks.
Finally, I wanted to do a contest and thanks to the folks at Displate.com, I am doing my
first one.
The contest is really very simple, I want to start building the email list for Deep
Astronomy because this week I finally found an editor for our newsletter.
This newsletter will be a great way to keep in touch with the latest things going on not
only on this YouTube channel but with everything we’ve got going on.
We’re still discussing the frequency of the newsletter but I promise you it will be
no more than one per week, I won’t spam you nor use your email address for anything
else, nor will I give them or sell them to anyone.
I hate that as much as you do.
I’m doing this because as you may have noticed with some of the changes to SFN, I’m trying
to build a Space Fan community and this newsletter is just one more way I can do that.
It’s a great way for me to reach you directly to let you know about things.
I also have a forum coming soon where we can discuss things like which stories we’re
all covering and discuss general topics of interest to us.
Entering is simple, just go to DeepAstronomy.com and sign up for our newsletter.
Each week, for the next three weeks I’ll pick a winner from among the people who signed
up using Random.org.
And don’t worry, if you’ve already signed up, you’re entered!
This wouldn’t be possible without the generosity of the folks at Displate.com.
They reached out to me a while ago about the possibility of a promotion and offered three
astronomy pictures for free to handout to my audience.
What they do is really cool, click on the link in the description box to learn more
about what they have but they print art and images onto metal surfaces and they have a
really neat space section.
Don’t worry that link isn’t an affiliate, just a tracking link so they can see how effective
this was for them.
I won’t get any compensation for it.
I’m promoting them because I like the company and they offered to help.
And I would buy some of those pictures myself!
Here is this week’s picture.
I chose three space images and the first one is this one on Mars.
It’s printed on a metal plate and very durable.
So sign up for the newsletter on DeepAstronomy.com to be entered.
I’ll make the drawing next Friday and send out an email to the winner.
I’ll do the same thing next week!
And the final one a week later.
Well, that’s it for this week Space Fans, remember I’ll be going to the March for
Science in Washington April 22 and will be doing some live streaming while I’m there.
SFN is made possible by all Patreon Patrons whose support keeps this show going - thank
you all so much.
Thanks to all of you for watching and as always, Keep Looking Up!