While Opportunity and Curiosity continue to explore the surface of Mars, the launch date of NASA’s next big rover mission is on the horizon. And here’s a stunning artist’s impression of the mission that NASA released on Tuesday.
Wait. Isn’t that Curiosity?
No. While the Mars 2020 rover will certainly look like Curiosity, as many of the current rover’s design features will be worked into NASA’s next six-wheeled robot, there will be some key differences in the next rover’s science.
Rather than seeking out past and present habitable environments (as Curiosity is currently doing on the slopes of Mount Sharp), one of Mars 2020’s stated science goals is to directly search for biological signatures of past and present microbial life on Mars. This next-generation rover will also feature a drill that can bore deep into rocks, pull samples and store them on the Martian surface for a possible future sample return mission.
After studying computer simulations of planetary collisions, scientists have discovered a possible phase of planetary formation that has, so far, been overlooked by astronomy. And they think this phase is so significant that it deserves its own planetary definition.
After two planetary objects collide, researchers from the University of California Davis and Harvard University in Cambridge, Mass., realized that a bloated, spinning mass of molten rock can form. It looks a bit like a ring doughnut with the hole filled in. What’s more, it is thought that Earth (and other planets in the solar system) probably went through this violent period before becoming the solid spinning globes we know and love today.
They call this partly vaporized rock “synestia” — “syn-” for “together” and “Estia” after the Greek goddess of architecture and structures.
Over a range of masses and collision speeds, planetary scientist Sarah Stewart (Davis) and graduate student Simon Lock (Harvard) simulated planetary collisions and focused on how the angular momentum of colliding bodies might influence the system. Their study has been published in the Journal of Geophysical Research: Planets. Basically, when two bodies — with their own angular momentum — collide and merge, the sum of their momenta must be conserved and this can have a dramatic effect on the size and structure of the merged mass.
“We looked at the statistics of giant impacts, and we found that they can form a completely new structure,” said Stewart.
After colliding, the energetic event causes both planets to melt and partially vaporize, expanding with a connected ring-like structure. And this structure — a synestia — would eventually cool, contract and solidify. It could also form moons; post-collision molten debris in the synestia doughnut ring may emerge in a stable orbit around the planet.
The synestia phase would be a fleeting event in any planet’s life, however. For an Earth-sized mass, the post-collision synestia would likely last only 100 years or so. But the larger the mass, the longer the phase, the researchers theorize.
So, giving this theoretical “planetary object” a classification might be a little generous — a move that would raise recently “demoted” Pluto’s eyebrow — but as telescopes become more advanced, we might one day be lucky enough to spy a synestia in a young star system where dynamic instabilities are causing planets to careen into one another.
In our quest to understand what the heck is going on with Tabby’s Star, astronomers have been given a cosmic gift — a dimming event is happening right now and they’re collecting data in real time.
Early Friday morning, the star — officially designated KIC 8462852 — dipped in brightness inextricably and bulletins started to fly around the internet. Astronomers involved in the original discovery took to Twitter to announce the awesomeness and rally the world’s observatories to point their telescopes at the action 1,300 light-years away:
But why all the excitement? Well, this is the same star that, last year, hogged the headlines with speculation that a super advanced alien civilization was building some kind of “megastructure” around the star. (You can read my article on it here.) But why would the world’s media, let alone professional scientists, be okay with even hinting at the “alien” thing?
Well, as part of the Planet Hunters project, Tabby’s Star is wonderfully weird. After analyzing observations from NASA’s exoplanet-hunting Kepler Space Telescope, the citizen scientists noticed something peculiar.
Usually, Kepler’s ultra-sensitive optics detect the slight dimming of stars when any planets in orbit drift in front — an event known as a “transit.” These transits are typically very slight, but the signals detected at KIC 8462852 were mind-boggling. Between 2011 and 2013, Tabby’s Star exhibited a series of dips, dimming the brightness of the star by over 20 percent. Tabby’s Star was so-named after astronomer Tabetha Boyajian who led this research. Further studies of the star has also revealed a longer period of dimming.
And on Friday morning, it started happening again.
“At about 4 a.m. this morning, I got a phone call from Tabby [Boyajian] saying that Fairborn [Observatory] in Arizona had confirmed that the star was 3 percent dimmer than it normally is and that is enough that we are absolutely confident that this is no statistical fluke,” said Jason Wright, an associate professor of astronomy at Pennsylvania State University, during a live webcast. “We’ve now got it confirmed at multiple observatories I think.”
Now that astronomers are able to observe the star while the dimming is happening live (rather than studying past observations, which as been the case up until now), spectra of the star can be recorded and compared to previous data. This spectral information might reveal what material is causing the weird transit signals, potentially ruling some hypotheses out. But it might also create new questions.
Many hypotheses have been put forward for these unprecedented events before Friday. The most popular natural explanation has been the possibility that a giant “swarm” of comets drifted between the star and us, blocking the starlight. But this explanation falls short and doesn’t really explain why the brightness dips are so dramatic.
The most popular unnatural explanation is — you guessed it — aliens and astronomers are having a really hard job disproving this hypothesis. This idea is based around the possibility that a super advanced alien civilization (that’s well on its way to becoming a type II Kardashev civilization) is building a star-spanning solar array, akin to a Dyson swarm. In this scenario, the dimming in brightness would be caused by vast solar arrays blocking the light from view.
Now that the dimming is happening again, it will be interesting to see how the megastructure idea evolves.
Although imagining super-advanced aliens building stuff around a nearby star is fun, this episode so early in our hunt for extrasolar worlds is giving us a glimpse of just how strange our galaxy can be. In all likelihood, it probably isn’t an alien megastructure and more likely something astronomers have completely overlooked. But it could also be that these Kepler data are being caused by a natural stellar phenomenon that we’ve never seen before — a possibility that could be revealed very soon.
ALMA is no stranger to protoplanetary disks; the array of 66 radio antennae in the Atacama desert is extremely sensitive to the emissions from the gas and dust surrounding stars. But this observation has revealed something more — there are two obvious dusty rings (orange) that are being sculpted by the presence of massive worlds, but between them (in blue) is a spiral gas structure. If there’s one thing I love it’s space spirals!
When comparing these observations with theoretical modeling of the system — called AB Aurigae, located about 470 light-years away — for that gas spiral to exist, there must be some interplanetary interplay between two exoplanets orbiting the star at 30 and 80 AU (astronomical units, where 1 AU is the average distance that Earth orbits the sun). The spiral is following the direction of rotation of the disk.
Besides looking really pretty, studies of these spiral structures help astronomers identify the presence of exoplanets and build a better understanding of the nature of protoplanetary disks.
In 2013, when I heard that Iain M. Banks had passed away at the tragically young age of 59, I was devastated. As I wrote at the time, it’s always hard when a person who inspired you in life dies. But in the years since Banks’ death of terminal cancer, I’ve spent more time reading and re-reading his science fiction works, somehow uncovering new detail and surprises in each chapter. His epic Culture series is as impactful now as it was when he wrote his 1987 novel “Consider Phlebas.”
I’ve also been researching the man himself, learning about his motivations, political opinions and religious beliefs (or lack thereof) to find we share many of the same views about the state of the world. And recently, I came across his final “Raw Spirit” interview with Kirsty Wark of BBC Scotland that he did in the weeks before he died.
The interview is excellent and well worth the watch.
One discussion I found particularly poignant was at around the 35 minute mark when Kirsty asks Iain about his views on life elsewhere in the universe:
There’s so many stars in the galaxy and there are so many galaxies … it seems highly unlikely there’s just us. It’s one of the things that I regret a great deal is that I’m not going to live long enough to see the results come in from the really good telescopes that we’re putting in space, in particular. They’ll actually be able to analyze the composition of exoplanets, their atmospheres, and be able to tell whether they’ve got life in them. You know exactly what the spectrum is of the star, as the star starts to slip behind the planet, the way the spectrum alters … will tell you how much carbon, how much oxygen, carbon dioxide and so on is in the atmosphere of that planet. It’s astounding to think we might know this in 10, 20 years. Yeah. It’s damned annoying! (laughs)
Iain’s views on life elsewhere in the universe are hardly surprising, especially considering all the alien civilizations he’d created through his decades of writing. And his point about detecting chemicals in exoplanetary atmospheres is rooted very firmly in science fact. I can’t begin to imagine his annoyance at knowing we’re only years away from probing alien atmospheres when his life was almost up. (For added poignancy, Iain hints that he has months left to live, but as indicated at the start of the interview, it turned out he was in his final weeks.)
I found Iain’s humor and energy inspiring in life, and despite facing his imminent mortality during this interview, he delivered some thought-provoking ideas and views with grace that will live on well beyond his death.
Supermassive black holes can be millions to billions of times the mass of our sun. To grow this big, you’d think these gravitational behemoths would need a lot of time to grow. But you’d be wrong.
When looking back into the dawn of our universe, astronomers can see these monsters pumping out huge quantities of radiation as they consume stellar material. Known as quasars, these objects are the centers of primordial galaxies with supermassive black holes at their hearts.
Now, using the twin W. M. Keck Observatory telescopes on Hawaii, researchers have found three quasars all with billion solar mass supermassive black holes in their cores. This is a puzzle; all three quasars have apparently been active for short periods and exist in an epoch when the universe was less than a billion years old.
Currently, astrophysical models of black hole accretion (basically models of how fast black holes consume matter — likes gas, dust, stars and anything else that might stray too close) woefully overestimate how long it takes for black holes to grow to supermassive proportions. What’s more, by studying the region surrounding these quasars, researchers at the Max Planck Institute for Astronomy (MPIA) in Germany have found that these quasars have been active for less than 100,000 years.
To put it mildly, this makes no sense.
“We don’t understand how these young quasars could have grown the supermassive black holes that power them in such a short time,” said lead author Christina Eilers, a post-doctorate student at MPIA.
Using Keck, the team could take some surprisingly precise measurements of the quasar light, thereby revealing the conditions of the environment surrounding these bright baby galaxies.
Models predict that after forming, quasars began funneling huge quantities of matter into the central black holes. In the early universe, there was a lot of matter in these baby galaxies, so the matter was rapidly consumed. This created superheated accretion disks that throbbed with powerful radiation. The radiation blew away a comparatively empty region surrounding the quasar called a “proximity zone.” The larger the proximity zone, the longer the quasar had been active and therefore the size of this zone can be used to gauge the age (and therefore mass) of the black hole.
But the proximity zones measured around these quasars revealed activity spanning less than 100,000 years. This is a heartbeat in cosmic time and nowhere near enough time for a black hole pack on the supermassive pounds.
“No current theoretical models can explain the existence of these objects,” said Joseph Hennawi, who led the MPIA team. “The discovery of these young objects challenges the existing theories of black hole formation and will require new models to better understand how black holes and galaxies formed.”
The researchers now hope to track down more of these ancient quasars and measure their proximity zones in case these three objects are a fluke. But this latest twist in the nature of supermassive black holes has only added to the mystery of how they grow to be so big and how they relate to their host galaxies.
As I freelance for other websites, I thought I’d begin posting links and summaries here on a quasi-regular basis so you can keep up with the other space stuff I write about. So, to kick off the Astroengine Roundup, here you go:
Ever since H. G. Wells wrote “The Time Machine” in 1895, we’ve been fascinated with the possibility of magically bouncing around through history. But it wasn’t until Einstein published his historic theory of general relativity that scientists (and science fiction writers) realized that time wasn’t necessarily as ridged as classical theories predicted. After a thought-provoking chat with general relativity expert Ben Tippett, of the University of British Columbia, I was able to get the lowdown on his mathematical model of a time machine called… TARDIS.
When Europe’s Rosetta mission discovered molecular oxygen venting from comet 67P/Churyumov-Gerasimenko in 2015, scientists were weirded out. In space, molecular oxygen (O2, i.e. the stuff we breathe) is highly reactive and will break down very quickly. The working theory was that the O2 had been locked in the comet’s ices for billions of years since the solar system’s earliest moments, but new research suggests that 67P is actually producing its own O2 right this moment from a complex interplay between the venting water molecules and chemicals on the comet’s surface. Yes, comets are therefore molecular oxygen factories.
Not So Fast: Magnetic Mystery of Sun’s ‘Stealth’ Eruptions Uncovered (SPACE.com)
Coronal mass ejections, or CMEs, are the most dramatic eruptions that our sun can produce. If they are Earth-directed, these magnetized bubbles of superheated plasma can cause all kinds of issues for our high-technology civilization. Usually, space weather forecasters do a great job of at least predicting when these eruptions might be triggered in the sun’s lower corona, but there’s a different type of CME — the so-called “stealth” CME — that appears to come out of nowhere, created by the complex interplay of magnetic fields high in the sun’s atmosphere.
There are few sights on Mars more satisfying than its oddly familiar — yet weirdly alien — dunes.
On the one hand, the Martian dunes look much like the dunes we have on Earth — aeolian (“wind-driven”) formations undulating across the landscape have similarities regardless of which planet they were blown on.
But there’s something uncanny about Martian dunes. Maybe it’s the “extra” tiny ripples that NASA’s Curiosity itself discovered — a phenomenon that is exclusive to the Martian atmosphere. Or maybe it’s just that I know these dunes are being seen through synthetic eyes on a world millions of miles across the interplanetary void.
But right now, the six-wheeled robot is sampling grains of wind-blown regolith from a linear dunes on the slopes of Mount Sharp to help planetary scientists on Earth build a picture of how this ancient landscape was shaped.
Curiosity scooped samples of linear dune material into the rover’s Sample Analysis at Mars (SAM) so they could be compared with material from other dunes it had visited in 2015 and 2016. Samples are also planned to be delivered to the mission’s Chemistry and Mineralogy (CheMin) instrument. As NASA points out, this is the first ever study of extraterrestrial dunes. (Dune fields also exist on Saturn’s moon Titan, but as recent research indicates, those are very different beasts and haven’t been directly sampled.)
“At these linear dunes, the wind regime is more complicated than at the crescent dunes we studied earlier,” said Mathieu Lapotre, of the California Institute of Technology (Caltech), in Pasadena, Calif., who led the Curiosity dune campaign. “There seems to be more contribution from the wind coming down the slope of the mountain here compared with the crescent dunes farther north.”
All of the dunes Curiosity has sampled are a part of the Bagnold Dunes, a dune field that stretches up the northwestern flank of Mount Sharp. Within the field, depending on the wind conditions, different types of dunes have been found.
“There was another key difference between the first and second phases of our dune campaign, besides the shape of the dunes,” said Lapotre in a NASA statement. “We were at the crescent dunes during the low-wind season of the Martian year and at the linear dunes during the high-wind season. We got to see a lot more movement of grains and ripples at the linear dunes.”
It’s official, there’s a whole lot of nothing in Saturn’s innermost ring gap.
This blunt — and slightly mysterious — conclusion was reached when scientists studied Cassini data after the spacecraft’s first dive through the gas giant’s ring plane. At first blush, this might not sound so surprising; the 1,200-mile-wide gap between Saturn’s upper atmosphere and the innermost edge of its rings does appear like an empty place. But as the NASA spacecraft barreled through the gap on April 26, mission scientists expected Cassini to hit a few stray particles on its way through.
Instead, it hit nothing. Or, at least, far fewer particles than they predicted.
“The region between the rings and Saturn is ‘the big empty,’ apparently,” said Earl Maize, Cassini’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Cassini will stay the course, while the scientists work on the mystery of why the dust level is much lower than expected.”
Using Cassini’s Radio and Plasma Wave Science (RPWS), the scientists expected to detect multiple “cracks and pops” as the spacecraft shot through the gap. Instead, it picked up mainly signals from energetic charged particles buzzing in the planet’s magnetic field. When converted into an audio file, these signals make a whistling noise and this background whistle was expected to be drowned out by the ruckus of dust particles bouncing off the spacecraft’s body. But, as the following audio recording proves, very few pops and cracks of colliding debris were detected — it sounds more like an off-signal radio tuner:
Compare that with the commotion Cassini heard as it passed through the ring plane outside of Saturn’s rings on Dec. 18, 2016:
Now that is what it sounds like to get smacked by a blizzard of tiny particles at high speed.
“It was a bit disorienting — we weren’t hearing what we expected to hear,” said William Kurth, RPWS team lead at the University of Iowa, Iowa City. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.”
From this first ring gap dive, NASA says Cassini likely only hit a handful of minute, 1 micron particles — particles no larger than those found in smoke. And that’s a bit weird.
As weird as it may be, the fact that the region of Cassini’s first ring dive is emptier than expected now allows mission scientists to carry out optimized science operations with the spacecraft’s instruments. On the first pass, Cassini’s dish-shaped high-gain antenna was used as a shield to protect the spacecraft as it made the dive. On its next ring dive, which is scheduled for Tuesday at 12:38 p.m. PT (3:38 p.m. ET), this precaution is evidently not needed and the spacecraft will be oriented to better view the rings as it flies through.
So there we have it, the first mysterious result of Cassini’s awesome Grand Finale! 21 ring dives to go…