Many of the moons and planets across the Universe are in resonance with each other and their star. What causes this resonance, and how can it help us understand the history of planetary formation and migration?
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
The Messier 61 galaxy, as imaged by the Hubble Space Telescope. Credits: ESA/Hubble & NASA/G. Chapdelaine, L. Limatola and R. Gendler
Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the barred spiral galaxy known as Messier 61.
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects he initially mistook for comets. In time, he would come to compile a list of approximately 100 of these objects, hoping to prevent other astronomers from making the same mistake. This list – known as the Messier Catalog – would go on to become one of the most influential catalogs of Deep Sky Objects.
One of these objects is the intermediate barred spiral galaxy known as Messier 61. As one of the larger galaxies located in the Virgo Cluster, this galaxy is roughly 52.5 million light years from Earth and contains some spectacular supernovae. It also has an Active Galactic Nucleus (AGN), meaning it has a Supermassive Black Hole (SMBH) at its center, and shows evidence of considerable star formation.
What You Are Looking At:
Spanning about 100,000 light years across and about the same size as our own Milky Way Galaxy, this grand old spiral is one of the largest in the Virgo Cluster… and one of the most active in terms of starbursts and supernovae. According to Luis Colina (et al) indicated in a 1997 study:
“A high-resolution Hubble Space Telescope WFPC2 F218W UV image of the barred spiral NGC 4303 (classified as a LINER-type active galactic nucleus [AGN]) reveals for the first time the existence of a nuclear spiral structure of massive star-forming regions all the way down to the UV-bright unresolved core of an active galaxy. The spiral structure, as traced by the UV-bright star-forming regions, has an outer radius of 225 pc and widens as the distance from the core increases. The UV luminosity of NGC 4303 is dominated by the massive star-forming regions, and the unresolved LINER-type core contributes only 16% of the integrated UV luminosity. The nature of the UV-bright LINER-type core—stellar cluster or pure AGN—is still unknown.”
The Virgo Cluster Galaxies. Credit & Copyright: Rogelio Bernal Andreo
Another fascinating aspect is Colina’s team has also identified a Super Star Cluster (SSC) withing Messier 61 as well. As Colina indicated in a 2002 study:
“These new HST/STIS results unambiguously show the presence of a compact SSC in the nucleus of a low-luminosity AGN, which is also its dominant ionizing source. We hypothesize that at least some LLAGNs in spirals could be understood as the result of the combined ionizing radiation emitted by an evolving SSC (i.e., determined by the mass and age) and a black hole accreting with low radiative efficiency (i.e., radiating at low sub-Eddington luminosities) coexisting in the inner few parsecs region. Complementary multifrequency studies give the first hints of the very complex structure of the central 10 pc of NGC 4303, where a young SSC apparently coexists with a low-efficiency accreting black hole and with an intermediate/old compact star cluster and where, in addition, an evolved starburst could also be present. If structures such as those detected in NGC 4303 are common in the nuclei of spirals, the modeling of the different stellar components and their contribution to the dynamical mass has to be established accurately before deriving any firm conclusion about the mass of central black holes of few to several million solar masses.”
Of course, studies don’t just stop there. As D. Tschoke (et al) indicated in a 2000 study:
“The late-type galaxy NGC 4303 (M61) is one of the most intensively studied barred galaxies in the Virgo Cluster. Its prominent enhanced star formation throughout large areas of the disk can be nicely studied due to its low inclination of about 27 degr. We present observations of NGC 4303 with the ROSAT PSPC and HRI in the soft X-ray (0.1-2.4 keV). The bulk of the X-ray emission is located at the nuclear region. It contributes more than 80% to the total observed soft X-ray flux. The extension of the central X-ray source and the L_X/L_Halpha ratio point to a low luminous AGN (LINER) with a circumnuclear star-forming region. Several separate disk sources can be distinguished with the HRI, coinciding spatially with some of the most luminous HII regions outside the nucleus of NGC 4303. The total star formation rate amounts to 1-2 Msun/yr. The X-ray structure follows the distribution of star formation with enhancement at the bar-typical patterns. The best spectral fit consists of a power-law component (AGN and HMXBs) and a thermal plasma component of hot gas from supernova remnants and superbubbles. The total 0.1-2.4 keV luminosity of NGC 4303 amounts to 5×10^40 erg/s, consistent with comparable galaxies, like e.g. NGC 4569.”
Hubble picture is the sharpest ever image of the core of spiral galaxy Messier 61. Taken using the High Resolution Channel of Hubble’s Advanced Camera for Surveys. Credit: ESA/NASA/HST
When it comes right down to it, it’s all about that star-forming ring. Said Eva Schinnerer (eta al) in a 2002 study:
“The UV continuum traces a complete ring that is heavily extincted north of the nucleus. Such a ring forms in hydrodynamic models of double bars, but the models cannot account for the UV emission observed on the leading side of the inner bar. Comparison with other starburst ring galaxies where the molecular gas emission and the star-forming clusters form a ring or tightly wound spiral structure suggests that the starburst ring in NGC 4303 is in an early stage of formation.”
How will today’s technologies continue to study the magnificent M61? Just take a look at what MOS can do! The very efficient multi-object-slit observing technique with the multi-mode instrument FORS1 has been demonstrated on the Virgo cluster galaxy NGC 4303 . Nineteen moveable slits at the instrument focal plane are positioned so that the faint light from several H II regions in this galaxy can pass into the spectrograph, while the much stronger “background” light (from the nearby areas in the galaxy and, to a large extent, from the Earth”s upper atmosphere) is blocked by the mask.
History of Observation:
M61 was discovered by Barnabus Oriani on May 5, 1779 when following the comet of that year. Said he, “Very pale and looking exactly like the comet.” As for our hero, Messier, he had also seen it on the same night – but thought it was the comet! Because Charles Messier was a good astronomer, he returned nightly to observe movement and it only took him a few days to realize his mistake and to admit it in his own notes:
“May 11, 1779. 61. 12h 10m 44s (182d 41′ 05″) +5d 42′ 05″ – Nebula, very faint & difficult to perceive. M. Messier mistook this nebula for the Comet of 1779, on the 5th, 6th and 11th of May; on the 11th he recognized that this was not the Comet, but a nebula which was located on its path and in the same point of the sky.”
Supernova SN2008in in the spiral galaxy Messier 61. Credit: Hewholooks/ Wikipedia Commons
Sir William and Sir John Herschel would also later return to M61 to assign it their own catalog numbers, both resolving certain portions of this wonderful galaxy – but neither truly beginning to understand what they were seeing. That took Admiral Smyth, who recorded in his notes:
“A large pale-white nebula, between the Virgo’s shoulders. This is a well defined object, but so feeble as to excite surprise that Messier detected it with his 3 1/2 foot telescope in 1779. Under the best action of my instrument it blazes towards the middle; but in H. [John Herschel]’s reflector it is faintly seen to be bicentral [an illusion caused by the bar], the nuclei 90″ apart, and lying sp [south preceding, SW] and nf [north following, NE]. It is preceded by four telescopic stars, and followed by another. Differentiated with the following object [17 Virginis], from which it bears about south by west, and is within a degree’s distance. This object is an outlier of a vast mass of discrete but neighboring nebulae, the spherical forms of which are indicative of compression.”
Locating Messier 61:
Locating Messier 61 is the Virgo Galaxy fields is relatively easily because it is so large and bright compared to any others in the area. Begin your hunt by identifying Beta and Delta Virginis. Between this pair you will see finderscope or binocular visible stars 17 and 16 Virginis. You destination is between this pair of stars. While M61 is binocular possible, it would require astronomical binoculars of approximately 80mm aperture and dark skies – although with excellent sky conditions the nucleus can be glimpsed with apertures as small as 60mm.
This star chart for M61 represents the view from mid-northern latitudes for the given month and time. Credits: NASA/Stellarium
In a small aperture telescope, M61 will appear as a very faint oval with a bright central region. As size increases, so do details and resolution. At 6-8″ in size, the nucleus becomes very clear and beginnings of spiral arms start to resolve. In the 10-12″ range, spiral structure becomes clear and some mottling texture becomes clear.
Enjoy your observations!
And here are the quick facts on Messier 61 to help you get started:
Object Name: Messier 61
Alternative Designations: M61, NGC 4303
Object Type: Type SABbc Spiral Galaxy
Constellation: Virgo
Right Ascension: 12 : 21.9 (h:m)
Declination: +04 : 28 (deg:m)
Distance: 60000 (kly)
Visual Brightness: 9.7 (mag)
Apparent Dimension: 6×5.5 (arc min)
This image shows a visual representation of one of the highest-energy neutrino detections superimposed on a view of the IceCube Lab at the South Pole. Credit: IceCube Collaboration
At the Amundsen–Scott South Pole Station in Antarctica lies the IceCube Neutrino Observatory – a facility dedicated to the study of elementary particles known as neutrino. This array consists of 5,160 spherical optical sensors – Digital Optical Modules (DOMs) – buried within a cubic kilometer of clear ice. At present, this observatory is the largest neutrino detector in the world and has spent the past seven years studying how these particles behave and interact.
The most recent study released by the IceCube collaboration, with the assistance of physicists from Pennsylvania State University, has measured the Earth’s ability to block neutrinos for the first time. Consistent with the Standard Model of Particle Physics, they determined that while trillions of neutrinos pass through Earth (and us) on a regular basis, some are occasionally stopped by it.
The IceCube Neutrino Observatory at the South Pole. Credit: Emanuel Jacobi/NSF
Back in 2013, the first detections of high-energy neutrinos were made by IceCube collaboration. These neutrinos – which were believed to be astrophysical in origin – were in the peta-electron volt range, making them the highest energy neutrinos discovered to date. IceCube searches for signs of these interactions by looking for Cherenkov radiation, which is produced after fast-moving charged particles are slowed down by interacting with normal matter.
By detecting neutrinos that interact with the clear ice, the IceCube instruments were able to estimate the energy and direction of travel of the neutrinos. Despite these detections, however, the mystery remained as to whether or not any kind of matter could stop a neutrino as it journeyed through space. In accordance with the Standard Model of Particle Physics, this is something that should happen on occasion.
After observing interactions at IceCube for a year, the science team found that the neutrinos that had to travel the farthest through Earth were less likely to reach the detector. As Doug Cowen, a professor of physics and astronomy/astrophysics at Penn State, explained in a Penn State press release:
“This achievement is important because it shows, for the first time, that very-high-energy neutrinos can be absorbed by something – in this case, the Earth. We knew that lower-energy neutrinos pass through just about anything, but although we had expected higher-energy neutrinos to be different, no previous experiments had been able to demonstrate convincingly that higher-energy neutrinos could be stopped by anything.”
The Icetop Tank, the neutrino detectors at the heart of the IceCube Neutrino Observatory. Credit: Dan Hubert
The existence of neutrinos was first proposed in 1930 by theoretical physicist Wolfgang Pauli, who postulated their existence as a way of explaining beta decay in terms of the conservation of energy law. They are so-named because they are electrically neutral, and only interact with matter very weakly – i.e. through the weak subatomic force and gravity. Because of this, neutrinos pass through normal matter on a regular basis.
Whereas neutrinos are produced regularly by stars and nuclear reactors here on Earth, the first neutrinos were formed during the Big Bang. The study of their interaction with normal matter can therefore tell us much about how the Universe evolved over the course of billions of years. Many scientists anticipate that the study of neutrinos will indicate the existence of new physics, ones which go beyond the Standard Model.
Because of this, the science team was somewhat surprised (and perhaps disappointed) with their results. As Francis Halzen – the principal investigator for the IceCube Neutrino Observatory and a professor of physics at the University of Wisconsin-Madison – explained:
“Understanding how neutrinos interact is key to the operation of IceCube. We were of course hoping for some new physics to appear, but we unfortunately find that the Standard Model, as usual, withstands the test.
Looking down one of IceCube’s detector bore holes. Credit: IceCube Collaboration/NSF
For the most part, the neutrinos selected for this study were more than one million times more energetic than those that are produced by our Sun or nuclear power plants. The analysis also included some that were astrophysical in nature – i.e. produced beyond Earth’s atmosphere – and may have been accelerated towards Earth by supermassive black holes (SMBHs).
Darren Grant, a professor of physics at the University of Alberta, is also the spokesperson for the IceCube Collaboration. As he indicated, this latest interaction study opens doors for future neutrino research. “Neutrinos have quite a well-earned reputation of surprising us with their behavior,” he said. “It is incredibly exciting to see this first measurement and the potential it holds for future precision tests.”
This study not only provided the first measurement of the Earth’s absorption of neutrinos, it also offers opportunities for geophysical researchers who are hoping to use neutrinos to explore Earth’s interior. Given that Earth is capable of stopping some of the billions of high-energy particles that routinely pass through it, scientists could develop a method for studying the Earth’s inner and outer core, placing more accurate constraints on their sizes and densities.
It also shows that the IceCube Observatory is capable of reaching beyond its original purpose, which was particle physics research and the study of neutrinos. As this latest study clearly shows, it is capable of contributing to planetary science research and nuclear physics as well. Physicists also hope to use the full 86-string IceCube array to conduct a multi-year analysis, examining even higher ranges of neutrino energies.
This event display shows “Bert,” one of two neutrino events discovered at IceCube whose energies exceeded one petaelectronvolt (PeV). Credit: Berkeley Labs.
As James Whitmore – the program director in the National Science Foundation’s (NSF) physics division (which provides support for IceCube) – indicated, this could allow them to truly search for physics that go beyond the Standard Model.
“IceCube was built to both explore the frontiers of physics and, in doing so, possibly challenge existing perceptions of the nature of universe. This new finding and others yet to come are in that spirit of scientific discovery.”
Ever since the discovery of the Higgs boson in 2012, physicists have been secure in the knowledge that the long journey to confirm the Standard Model was now complete. Since then, they have set their sets farther, hoping to find new physics that could resolve some of the deeper mysteries of the Universe – i.e. supersymmetry, a Theory of Everything (ToE), etc.
This, as well as studying how physics work at the highest energy levels (similar to those that existed during the Big Bang) is the current preoccupation of physicists. If they are successful, we might just come to understand how this massive thing known as the Universe works.
The Mars Spring Tire being tested at NASA GRS' Slope lab. Credit: NASA/JPL
The Curiosity Rover has made some incredible discoveries during the five years it has been operating on the surface of Mars. And in the course of conducting its research, the rover has also accrued some serious mileage. However, it certainly came as a surprise when during a routine examinations in 2013, members of the Curiosity science team noted that its wheels had suffered rips in their treads (followed by breaks reported in 2017).
Looking to the future, researchers at NASA’s Glenn Research Center hope to equip next-generation rovers with a new wheel. It is based on the “Spring Tire“, which NASA developed with Goodyear back in the mid-2000s. However, rather than using coiled steel wires woven into a mesh pattern (which was part of the original design) a team of NASA scientists has created a more durable and flexible version which could revolution space exploration.
When it comes right down to it, the Moon, Mars, and other bodies in the Solar System have harsh, punishing terrain. In the case of the Moon, the main issue is the regolith (aka. Moon dust) which covers the majority of its surface. This fine dust is essentially jagged bits of lunar rock which play havoc with engines and machine components. On Mars, the situation is slightly different, with regolith and sharp rocks covering most of the terrain.
Image taken by the Mars Hand Lens Imager (MAHLI) camera showing the condition of Curiosity’s left-middle and left-rear wheels. Credit: NASA/JPL-Caltech/MSSS
In 2013, after just a year on the surface, the Curiosity rover’s wheels began to show signs of wear and tear due it traversing unexpectedly harsh terrain. This led many to worry that the rover might not be able to complete its mission. It also led many at NASA’s Glenn Research Center to reconsider a design they had been working on almost a decade prior, which was intended for renewed missions to the Moon.
For NASA Glenn, tire development has been a focus of research for about a decade now. In this respect, they are returning to a time-honored tradition of NASA engineers and scientists, which began back in the Apollo era. At the time, both the American and Russian space programs were evaluating multiple tires designs for use on the lunar surface. Overall, three major designs were proposed.
First, you had the wheels specially designed for Lunokhod rover, a Russian vehicle whose name literally translates to “Moon Walker”. The wheel design for this rover consisted of eight rigid-rim, wire-mesh tires that were connected to their axles by bicycle-type spokes. Metal cleats were also mounted on the outside of the tire to ensure better traction in the lunar dust.
Then there was NASA’s concept for a Modularized Equipment Transporter (MET), which was developed with the support of Goodyear. This unpowered cart came with two nitrogen-filled, smooth rubber tires to make it easier to pull the cart through lunar soil and over rocks. And then there was the design for the Lunar Roving Vehicle (LRV), which was the last NASA vehicle to visit the Moon.
This crewed vehicle, which Apollo astronauts used to drive around on the challenging lunar surface, relied on four large, flexible wire-mesh wheels with stiff inner frames. During the mid-2000s, when NASA began planning on mounting new missions to the Moon (and future missions to Mars), they began reevaluating the LRV tire and incorporating new materials and technologies into the design.
The fruit of this renewed research was the Spring Tire, which was the work of mechanical research engineer Vivake Asnani, who worked closely with Goodyear to develop it. The design called for an airless, compliant tire made up of hundreds of coiled steel wires, which were then woven into a flexible mesh. This not only ensured light weight, but also gave the tires the ability to support high loads while conforming to the terrain.
To see how the Spring Tire would fare on Mars, engineers at NASA’s Glenn Research Center began testing them in the Slope lab, where they ran them through an obstacle course that simulated the Martian environment. While the tires performed generally well in simulated sand, they experienced problems when the wire mesh deformed after passing over jagged rocks.
To address this, Colin Creager and Santo Padua (a NASA engineer and materials scientist, respectively) discussed possible alternatives. In time, they agreed the steel wires should be replaced with nickel titanium, a shape memory alloy that is capable of retaining its shape under tough conditions. As Padua explained in a NASA Glenn video segment, the inspiration to use this alloy was very serendipitous:
“I just happened to be over in the building here, where the Slope lab is. And I was over here for a different meeting for the work that I do in shape memory alloys, and I happen to run into Colin in the hall. And I was like ‘what are you doing back and why aren’t you over in the impact lab?’ – because I knew him as a student. He said, ‘well, I’ve graduated, and I’ve been working out here full-time for awhile… I work in Slope.”
Despite working at JPL for ten years, Padua had not seen the Slope lab before and accepted an invitation to see what they were working on. After entering the lab and looking at the Spring Tires they were testing, Padua asked if they were experiencing problems with deformation. When Creager admitted that they were, Padua proposed a solution which just happened to be his field of expertise.
“I had never even heard of the term shape memory alloys before, but I knew [Padua] was a materials science engineer,” said Creager. “And so, since then we’ve been collaborating on these tires using his materials expertise, especially in shape memory alloys, to come up with this new tire that we think is really going to revolutionize planetary rover tires and potentially even tires for Earth too.”
The key to shape memory alloys is their atomic structure, which is assembled in such a way that the material “remember” its original shape and is able to return to it after being subjected to deformation and strain. After building the shape memory alloy tire, the Glenn engineers sent it to the Jet Propulsion Laboratory, where it was tested in the Mars Life Test Facility.
Overall, the tires not only performed well in simulated Martian sand, but were able to withstand going over punishing rocky outcroppings without difficulty. Even after the tires were deformed all the way down to their axles, they were able to retain their original shape. They also managed to do this while carrying a significant payload, which is another prerequisite when developing tires for exploration vehicles and rovers.
The priorities for the Mars Spring Tire (MST) are to offer greater durability, better traction in soft sand, and lighter weight. As NASA indicates on the MST website (part of the Glenn Research Center’s website), there are three major benefits to developing high performing compliant tires like the Spring Wheel:
“First, they would allow rovers to explore greater regions of the surface than currently possible. Secondly, because they conform to the terrain and do not sink as much as rigid wheels, they can carry heavier payloads for the same given mass and volume. Lastly, because the compliant tires can absorb energy from impacts at moderate to high speeds, they can be used on crewed exploration vehicles which are expected to move at speeds significantly higher than the current Mars rovers.”
The first available opportunity to test these tires out is just a few years away, when NASA’s Mars 2020 Rover will be sent to the surface of the Red Planet. Once there, the rover will pick up where Curiosity and other rovers have left off, searching for signs of life in Mars’ harsh environment. The rover is also tasked with preparing samples that will eventually be returned to Earth by a crewed mission, which is expected to take place sometime in the 2030s.
Artist’s impression of the first interstellar asteroid/comet, "Oumuamua". This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO/M. Kornmesser
Back in October, the announcement of the first interstellar asteroid triggered a flurry of excitement. Since that time, astronomers have conducted follow-up observations of the object known as 1I/2017 U1 (aka. `Oumuamua) and noted some rather interesting things about it. For example, from rapid changes in its brightness, it has been determined that the asteroid is rocky and metallic, and rather oddly-shaped.
Observations of the asteroid’s orbit have also revealed that it made its closest pass to our Sun back in September of 2017, and it is currently on its way back to interstellar space. Because of the mysteries this body holds, there are those who are advocating that it be intercepted and explored. One such group is Project Lyra, which recently released a study detailing the challenges and benefits such a mission would present. Continue reading “Project Lyra, a Mission to Chase Down that Interstellar Asteroid”
These dark, narrow, 100 meter-long streaks called recurring slope lineae flowing downhill on Mars are inferred to have been formed by contemporary flowing water. However, a new study by planetary scientists indicates that these may actually be the result of dry flows. Credits: NASA/JPL/University of Arizona
When robotic missions first began to land on the surface of Mars in the 1970s, they revealed a harsh, cold and desiccated landscape. This effectively put an end generations of speculation about “Martian canals” and the possibility of life on Mars. But as our efforts to explore the Red Planet have continued, scientists have found ample evidence that the planet once had flowing water on its surface.
In addition, scientists have been encouraged by the appearance of Recurring Slope Lineae (RSL), which were believed to be signs of seasonal water flows. Unfortunately, a new study by researchers from the U.S. Geological Survey indicates that these features may be the result of dry, granular flows. These findings are another indication that the environment could be too dry for microorganisms to survive.
This inner slope of a Martian crater has several of the seasonal dark streaks called “recurrent slope lineae,” or RSL, which were caputred by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter. Credits: NASA/JPL-Caltech/UA/USGS
For the sake of their study, the team consulted data from the High Resolution Image Science Experiment (HiRISE) camera aboard the NASA Mars Reconnaissance Orbiter (MRO). This same instrument was responsible for the 2011 discovery of RSL, which were found in the middle latitudes of Mars’ southern hemisphere. These features were also observed to appear on Martian slopes during late spring through summer and then fade away in winter.
The seasonal nature of these flows was seen as a strong indication that they were the result of flowing salt-water, which was indicated by the detection of hydrated salt at the sites. However, after re-examining the HiRISE data, Dundas and his team concluded that RSLs only occur on slopes that are steep enough for dry grains to descend – in much the same way that they would on the faces of active dunes.
“We’ve thought of RSL as possible liquid water flows, but the slopes are more like what we expect for dry sand. This new understanding of RSL supports other evidence that shows that Mars today is very dry.”
Using pairs of images from HiRISE, Dundas and his colleagues constructed a series of 3-D models of slope steepness. These models incorporated 151 RSL features identified by the MRO at 10 different sites. In almost all cases, they found that the RSL were restricted to slopes that were steeper than 27° and each flow ended on a slope that matched the patterns seen in slumping dry sand dunes on Mars and Earth.
Dark, narrow streaks flowing downhill on Mars at sites like the Horowitz Crater are inferred to be due to seasonal flows of water. Credit: NASA/JPL-Caltech/Univ. of Arizona
Basically, sand flows end where a steep angle gives way to a less-steep “angle of repose”, whereas liquid water flows are known to extend along less steep slopes. As Alfred McEwen, HiRISE’s Principal Investigator at the University of Arizona and a co-author of the study, indicated, “The RSL don’t flow onto shallower slopes, and the lengths of these are so closely correlated with the dynamic angle of repose, it can’t be a coincidence.”
These observations is something of a letdown, since the presence of liquid water in Mars’ equatorial region was seen as a possible indication of microbial life. However, compared to seasonal brine flows, the present of granular flows is a far better fit with what is known of Mars’ modern environment. Given that Mars’ atmosphere is very thin and cold, it was difficult to ascertain how liquid water could survive on its surface.
Nevertheless, these latest findings do not resolve all of the mystery surrounding RSLs. For example, there remains the question of how exactly these numerous flows begin and gradually grow, not to mention their seasonal appearance and the way they rapidly fade when inactive. On top of that, there is the matter of hydrated salts, which have been confirmed to contain traces of water.
To this, the authors of the study offer some possible explanations. For example, they indicate that salts can become hydrated by pulling water vapor from the atmosphere, which might explain why patches along the slopes experience changes in color. They also suggest that seasonal changes in hydration might result in some trigger mechanism for RSL grainflows, where water is absorbed and release, causing the slope to collapse.
NASA’s Mars Reconnaissance Orbiter investigating Martian water cycle. Credit: NASA/JPL/Corby Waste
If atmospheric water vapor is a trigger, then it raises another important question – i.e. why do RSLs appear on some slopes and not others? As Alfred McEwen – HiRISE’s Principal Investigator and a co-author on the study – explained, this could indicate that RSLs on Mars and the mechanisms behind their formation may not be entirely similar to what we see here on Earth.
“RSL probably form by some mechanism that is unique to the environment of Mars,” he said, “so they represent an opportunity to learn about how Mars behaves, which is important for future surface exploration.” Rich Zurek, the MRO Project Scientist of NASA’s Jet Propulsion Laboratory, agrees. As he explained,
“Full understanding of RSL is likely to depend upon on-site investigation of these features. While the new report suggests that RSL are not wet enough to favor microbial life, it is likely that on-site investigation of these sites will still require special procedures to guard against introducing microbes from Earth, at least until they are definitively characterized. In particular, a full explanation of how these enigmatic features darken and fade still eludes us. Remote sensing at different times of day could provide important clues.”
In the coming years, NASA plans to carry out the exploration of several sites on the Martian surface using the Mars 2020 rover, which includes a planned sample-return mission. These samples, after being collected and stored by the rover, are expected to be retrieved by a crewed mission mounted sometime in the 2030s, and then returned to Earth for analysis.
The days when we are finally able to study the Mars’ modern environment up close are fast approaching, and is expected to reveal some pretty Earth-shattering things!
A new study from the University of Edinburgh suggests that life could be distributed throughout the cosmos by interstellar dust. Credit: ESO/R. Fosbury (ST-ECF)
The theory of Panspermia states that life exists through the cosmos, and is distributed between planets, stars and even galaxies by asteroids, comets, meteors and planetoids. In this respect, life began on Earth about 4 billion years ago after microorganisms hitching a ride on space rocks landed on the surface. Over the years, considerable research has been devoted towards demonstrating that the various aspects of this theory work.
The latest comes from the University of Edinburgh, where Professor Arjun Berera offers another possible method for the transport of life-bearing molecules. According to his recent study, space dust that periodically comes into contact with Earth’s atmosphere could be what brought life to our world billions of years ago. If true, this same mechanism could be responsible for the distribution of life throughout the Universe.
For the sake of his study, which was recently published in Astrobiology under the title “Space Dust Collisions as a Planetary Escape Mechanism“, Prof. Berera examined the possibility that space dust could facilitate the escape of particles from Earth’s atmosphere. These include molecules that indicate the presence of life on Earth (aka. biosignatures), but also microbial life and molecules that are essential to life.
The theory of Panspermia states that life is distributed throughout the Universe by microbes traveling on objects between star system. Credit: NASA/Jenny Mottor
Fast-moving flows of interplanetary dust impact our atmosphere on a regular basis, at a rate of about 100,000 kg (110 tons) a day. This dust ranges in mass from 10-18 to 1 gram, and can reach speeds of 10 to 70 km/s (6.21 to 43.49 mps). As a result, this dust is capable of impacting Earth with enough energy to knock molecules out of the atmosphere and into space.
These molecules would consist largely of those that are present in the thermosphere. At this level, those particles would consist largely of chemically disassociated elements, such as molecular nitrogen and oxygen. But even at this high altitude, larger particles – such as those that are capable of harboring bacteria or organic molecules – have also been known to exist. As Dr. Berera states in his study:
“For particles that form the thermosphere or above or reach there from the ground, if they collide with this space dust, they can be displaced, altered in form or carried off by incoming space dust. This may have consequences for weather and wind, but most intriguing and the focus of this paper, is the possibility that such collisions can give particles in the atmosphere the necessary escape velocity and upward trajectory to escape Earth’s gravity.”
Of course, the process of molecules escaping our atmosphere presents certain difficulties. For starters, it requires that there be enough upward force that can accelerate these particles to escape velocity speeds. Second, if these particle are accelerated from too low an altitude (i.e. in the stratosphere or below), the atmospheric density will be high enough to create drag forces that will slow the upward-moving particles.
Photo of an aurora taken by astronaut Doug Wheelock from the International Space Station on July 25th, 2010. Credit: Image Science & Analysis Laboratory, NASA Johnson Space Center
In addition, as a result of their fast upward travel, these particle would undergo immense heating to the point of evaporation. So while wind, lighting, volcanoes, etc. would be capable of imparting huge forces at lower altitudes, they would not be able to accelerate intact particles to the point where they could achieve escape velocity. On the other hand, in the upper part of the mesosphere and thermosphere, particles would not suffer much drag or heating.
As such, Berera concludes that only atoms and molecules that are already found in the higher atmosphere could be propelled into space by space dust collisions. The mechanism for propelling them there would likely consist of a double state approach, whereby they are first hurled into the lower thermosphere or higher by some mechanism and then propelled even harder by fast space dust collision.
After calculating the speed at which space dust impacts our atmosphere, Berera determined that molecules that exist at an altitude of 150 km (93 mi) or higher above Earth’s surface would be knocked beyond the limit of Earth’s gravity. These molecules would then be in near-Earth space, where they could be picked up by passing objects such as comets, asteroid or other Near-Earth Objects (NEO) and carried to other planets.
Naturally, this raises another all-important question, which is whether or not these organisms could survive in space. But as Berera notes, previous studies have borne out the ability of microbes to survive in space:
“Should some microbial particles manage the perilous journey upward and out of the Earth’s gravity, the question remains how well they will survive in the harsh environment of space. Bacterial spores have been left on the exterior of the International Space Station at altitude ~400km, in a near vacuum environment of space, where there is nearly no water, considerable radiation, and with temperatures ranging from 332K on the sun side to 252K on the shadow side, and have survived 1.5 years.”
The tiny Tardigrade (aka. “water bear”), which could be the toughest creature on Earth. Credit: Katexic Publications, unaltered, CC2.0)
Another thing Berera considers is the strange case of tardigrades, the eight-legged micro-animals that are also known as “water bears”. Previous experiments have shown that this species is capable of surviving in space, being both strongly resistant to radiation and desiccation. So it is possible that such organisms, if they were knocked out of Earth’s upper atmosphere, could survive long enough to hitch a ride to another planet
In the end, these finding suggests that large asteroid impacts may not be the only mechanism responsible for life being transferred between planets, which is what proponents of Panspermia previously thought. As Berera stated in a University of Edinburgh press statement:
“The proposition that space dust collisions could propel organisms over enormous distances between planets raises some exciting prospects of how life and the atmospheres of planets originated. The streaming of fast space dust is found throughout planetary systems and could be a common factor in proliferating life.”
In addition to offering a fresh take on Panspermia, Berera’s study is also significant when it comes to the study of how life evolved on Earth. If biological molecules and bacteria have been escaping Earth’s atmosphere continuously over the course of its existence, then this would suggest that it could still be floating out in the Solar System, possibly within comets and asteroids.
These biological samples, if they could be accessed and studied, would serve as a timeline for the evolution of microbial life on Earth. It’s also possible that Earth-borne bacteria survive today on other planets, possibly on Mars or other bodies where they locked away in permafrost or ice. These colonies would basically be time capsules, containing preserved life that could date back billions of years.
Special Guests:
This week, we are SUPER excited to welcome author Andy Weir (The Martian), back to the show to chat with us about his new book, Artemis. Viewers who have seen Andy’s first appearance on our show on January 9, 2015, will remember just how awesome he is as a guest – and why we can’t wait to catch up with him this week.
Andy began his career as a software engineer but wrote science fiction stories in his spare time. His novel, THE MARTIAN, was a blockbuster success which has allowed him to pursue his writing full-time. He is a lifelong space nerd and a devoted hobbyist of subjects such as relativistic physics, orbital mechanics, and the history of manned spaceflight.
Announcements:
The WSH Crew is doing another book giveaway – this time in conjunction with Dean Regas‘ joining us again on November 29th in a pre-recorded interview. Dean’s new book, “100 Things to See in the Night Sky” hits the stores on November 28th, but we are giving our viewers a chance to win one of two copies of Dean’s book! (Note: telescope not included!)
To enter for a chance to win, send an email to [email protected] with the Subject ‘100 Things’. Be sure to include your name and email address in the body of your message so that we can contact our winners afterward.
To be eligible, your entry must be postmarked no later than 11:59:59 PM EST on Monday, November 27, 2017. Two winners will be selected at random from all eligible entries live on the show, by Fraser, on Wednesday, November 29th. No purchase is necessary. You do not need to be watching the show live to win. Contest is open to all viewers worldwide. Limit: One entry per person – duplicate entries will be ignored.
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Wednesday at 5:00 pm Pacific / 8:00 pm Eastern. You can watch us live on Universe Today, or the Weekly Space Hangout YouTube page – Please subscribe!
SpaceX Dragon CRS-9 was the last International Space Station resupply mission to lift off successfully from pad 40 on July 18, 2016, prior to the Cape Canaveral, FL, launch pad explosion with the Amos-6 payload that heavily damaged the pad and infrastructure on Sept. 1, 2016. Cargo launches for NASA will resume with Dragon CRS-13 in December 2017. Credit: Ken Kremer/kenkremer.com
SpaceX Dragon CRS-9 was the last International Space Station resupply mission to lift off successfully from pad 40 on July 18, 2016, prior to the Cape Canaveral, FL, launch pad explosion with the Amos-6 payload that heavily damaged the pad and infrastructure on Sept. 1, 2016. Cargo launches for NASA will resume with Dragon CRS-13 in December 2017. Credit: Ken Kremer/kenkremer.com
NASA and SpaceX have jointly decided to move forward with the Dragon CRS-13 cargo blastoff apparently because the mission does not involve use of the problematical payload fairing that halted last weeks planned Falcon 9 launch with the rocket and the mysterious Zuma payload.
Zuma was ready and waiting at pad 39A for the GO to launch that never came.
Then after a series of daily delays SpaceX ultimately announced a ‘stand down’ for super secret Zuma at pad 39A on Friday, Nov. 17, for the foreseeable future.
SpaceX Falcon 9 rocket blastoff of clandestine Zuma spysat to low earth orbit for a classified US government customer is postponed indefinitely from Launch Complex 39A at the Kennedy Space Center, FL, from last targeted launch date of 17 Nov 2017. Credit: Ken Kremer/Kenkremer.com
Since SpaceX’s gumdrop shaped Dragon cargo freighter launches as a stand alone aerodynamically shielded spacecraft atop the Falcon 9, it does not require additional protection from atmospheric forces and friction housed inside a nose cone during ascent to orbit unlike satellites with many unprotected exposed surfaces, critical hardware and delicate instruments.
Thus Dragon is deemed good to go since there currently appear to be no other unresolved technical issues with the Falcon 9 rocket.
“NASA commercial cargo provider SpaceX is targeting its 13th commercial resupply services mission to the International Space Station for no earlier than 2:53 p.m. EST Monday, Dec. 4,” NASA announced on the agency blog and social media accounts.
But the targeted Dec 4 liftoff from Space Launch Complex 40 on Cape Canaveral Air Force Station, FL, was cast in doubt after SpaceX disclosed the payload fairing issue related launch delay on Friday.
Since last week SpaceX engineers have been busy taking the time to carefully scrutinize all the pertinent fairing data before proceeding with the top secret Zuma launch.
“We have decided to stand down and take a closer look at data from recent fairing testing for another customer,” said SpaceX spokesman John Taylor last Friday.
Covert Zuma spysat is encapsulated inside the nose cose at the top of the SpaceX Falcon 9 rocket in this up-close view from Launch Complex 39A at the Kennedy Space Center, FL, taken on Nov. 17, 2017. An unresolved issue with the nose cone caused indefinite launch postponement. Credit: Ken Kremer/Kenkremer.com
All of SpaceX’s launches this year from Florida’s Spaceport have taken place from NASA’s historic Launch Complex-39A at the Kennedy Space Center.
Pad 39A became SpaceX’s only operational Florida Space Coast launch pad following a catastrophic launch pad accident last year on Sept. 1, 2016 that took place during a routine fueling test that suddenly ended in a devastating explosion and fire that completely consumed the Falcon 9 rocket and Amos-6 payload and heavily damaged the pad and support infrastructure.
Aerial view of pad and strongback damage at SpaceX Launch Complex-40 as seen from the VAB roof on Sept. 8, 2016 after fueling test explosion destroyed the Falcon 9 rocket and AMOS-6 payload at Cape Canaveral Air Force Station, FL on Sept. 1, 2016. Credit: Ken Kremer/kenkremer.com
Since the Amos-6 accident workers raced to finish refurbishments to NASA’s long dormant pad 39A to transform into operational status and successfully launched a dozen missions this year.
Simultaneously additional crews have been hard at work to repair damaged pad 40 so that flights can resume there as soon as possible for the bulk of NASA, commercial and military contracted missions.
The Dragon CRS-13 mission was recently announced as the maiden mission for the reopening of pad 40.
Altogether Dragon CRS-13 will count as the fourth SpaceX Dragon liftoff of 2017.
The 20-foot high, 12-foot-diameter Dragon CRS-13 vessel will carry about 3 tons of science and supplies to the orbiting outpost and stay about 4 weeks.
It will be a reused Dragon that previously flew on the CRS-6 mission.
“The Dragon [CRS-13] spacecraft will spend about a month attached to the space station,” NASA said.
SpaceX Falcon 9 rocket goes erect to launch position atop Launch Complex 39A at the Kennedy Space Center on 1 Jun 2017 as seen the morning before later afternoon launch from inside from the pad perimeter. Liftoff of the CRS-11 resupply mission to the International Space Station (ISS) slated for 1 June 2017. Credit: Ken Kremer/Kenkremer.com
The prior Dragon CRS-12 resupply ship launched from pad 39A on Aug. 14, 2017 from KSC pad 39A and carried more than 6,400 pounds ( 2,900 kg) of science experiments and research instruments, crew supplies, food water, clothing, hardware, gear and spare parts to the million pound orbiting laboratory complex.
Dragon CRS-9 was the last ISS resupply mission to launch from pad 40 on July 18, 2016.
The recently arrived Orbital ATK Cygnus cargo ship is expected to depart the station from the Earth facing Unity node on Dec. 3 to make way for Dragon’s berthing at the Harmony node.
Orbital ATK Antares rocket blasts off from the ‘On-Ramp’ to the International Space Station on Nov. 12, 2017 carrying the S.S. Gene Cernan Cygnus OA-8 cargo spacecraft from Pad 0A at NASA’s Wallops Flight Facility in Virginia. Credit: Ken Kremer/kenkremer.com
Watch for Ken’s continuing onsite coverage of SpaceX CRS-13, Zuma and KoreaSat-5A & Orbital ATK OA-8 Cygnus and NASA and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Up close view of SpaceX Dragon CRS-9 resupply ship and solar panels atop Falcon 9 rocket at pad 40 prior to blastoff to the ISS on July 18, 2016 from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer/kenkremer.comSpaceX Falcon 9 launches and lands over Port Canaveral in this streak shot showing rockets midnight liftoff from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida at 12:45 a.m. EDT on July 18, 2016 carrying Dragon CRS-9 craft to the International Space Station (ISS) with almost 5,000 pounds of cargo and docking port. View from atop Exploration Tower in Port Canaveral. Credit: Ken Kremer/kenkremer.com
An artist's illustration of a light-sail powered by a radio beam (red) generated on the surface of a planet. The leakage from such beams as they sweep across the sky would appear as Fast Radio Bursts (FRBs), similar to the new population of sources that was discovered recently at cosmological distances.
Credit: M. Weiss/CfA
The number of confirmed extra-solar planets has increased by leaps and bounds in recent years. With every new discovery, the question of when we might be able to explore these planets directly naturally arises. There have been several suggestions so far, ranging from laser-sail driven nanocraft that would travel to Alpha Centauri in just 20 years (Breakthrough Starshot) to slower-moving microcraft equipped with a gene laboratories (The Genesis Project).
But when it comes to braking these craft so that they can slow down and study distant stars and orbit planets, things become a bit more complicated. According to a recent study by the very man who conceived of The Genesis Project – Professor Claudius Gros of the Institute for Theoretical Physics Goethe University Frankfurt – special sails that rely on superconductors to generate magnetic fields could be used for just this purpose.
Starshot and Genesis are similar in that both concepts seek to leverage recent advancements in miniaturization. Today, engineers are able to create sensors, thrusters and cameras that are capable of carrying out computations and other functions, but are a fraction of the size of older instruments. And when it comes to propulsion, there are many options, ranging from conventional rockets and ion drives to laser-driven light sails.
Project Starshot, an initiative sponsored by the Breakthrough Foundation, is intended to be humanity’s first interstellar voyage. Credit: breakthroughinitiatives.org
Slowing an interstellar mission down, however, has remained a more significant challenge because such a craft cannot be fitted with braking thrusters and fuel without increasing its weight. To address this, Professor Gros suggests using magnetic sails, which would present numerous advantages over other available methods. As Prof. Gros explained to Universe Today via email:
“Classically, you would equip the spacecraft with rocket engines. Normal rocket engines, as we are using them for launching satellites, can change the velocity only by 5-15 km/s. And even that only when using several stages. That is not enough to slow down a craft flying at 1000 km/s (0.3% c) or 100000 km/s (c/3). Fusion or antimatter drives would help a bit, but not substantially.”
The sail he envisions would consist of a massive superconducting loop that measures about 50 kilometers in diameter, which would create a magnetic field once a lossless current was induced. Once activated, the ionized hydrogen in the interstellar medium would be reflected off the sail’s magnetic field. This would have the effect of transferring the spacecraft’s momentum to the interstellar gas, gradually slowing it down.
According to Gros’ calculations, this would work for slow-travelling sails despite the extremely low particle density of interstellar space, which works out to 0.005 to 0.1 particles per cubic centimeter. “A magnetic sail trades energy consumption with time,” said Gros.”If you turn off the engine of your car and let it roll idle, it will slow down due to friction (air, tires). The magnetic sail does the same, where the friction comes from the interstellar gas.”
Artist concept of lightsail craft approaching the potentially habitable exoplanet Proxima b. Credit: PHL @ UPR Arecibo
One of the advantages of this method is the fact that can be built using existing technology. The key technology behind the magnetic sail is a Biot Savart loop which, when paired with the same kind of superconducting coils used in high-energy physics, would create a powerful magnetic field. Using such a sail, even heavier spacecraft – those that weight up to 1,500 kilograms (1.5 metric tonnes; 3,307 lbs) – could be decelerated from an interstellar voyage.
The one big drawback is the time such a mission would take. Based on Gros’ own calculations, a high speed transit to Proxima Centauri that relied on magnetic momentum braking would require a ship that weighed about 1 million kg (1000 metric tonnes; 1102 tons). However, an interstellar mission involving a 1.5 metric tonne ship would be able to reach TRAPPIST-1 in about 12,000 years. As Gros concludes:
“It takes a long time (because the very low density of the interstellar media). That is bad if you want to see a return (scientific data, exciting pictures) in your lifetime. Magnetic sails work, but only when you are happy to take the (very) long perspective.”
In other words, such a system would not work for a nanocraft like that envisioned by Breakthrough Starshot. As Starshot’s own Dr. Abraham Loeb explained, the main goal of the project is to achieve the dream of interstellar travel within a generation of the ship’s departure. In addition to being the Frank B. Baird Jr. Professor of Science at Harvard University, Dr. Loeb is also the Chair of the Breakthrough Starshot Advisory Committee.
A phased laser array, perhaps in the high desert of Chile, propels sails on their journey. Credit: Breakthrough Initiatives
As he explained to Universe Today via email:
“[Gros] concludes that breaking on the interstellar gas is feasible only at low speeds (less than a fraction of a percent of the speed of light) and even then one needs a sail that is tens of miles wide, weighting tons. The problem is that with such a low speed, the journey to the nearest stars will take over a thousand years.
“The Breakthrough Starshot initiative aims to launch a spacecraft at a fifth of the speed of light so that it will reach the nearest stars within a human lifetime. It is difficult to get people excited about a journey whose completion will not be witnessed by them. But there is a caveat. If the longevity of people could be extended to millennia by genetic engineering, then designs of the type considered by Gros would certainly be more appealing.”
But for missions like The Genesis Project, which Gros originally proposed in 2016, time is not a factor. Such a probe, which would carry single-celled organisms – either encoded in a gene factory or stored as cryogenically-frozen spores – a could take thousands of years to reach a neighboring star system. Once there, it would begin seeding planets that had been identified as “transiently habitable” with single-celled organisms.
For such a mission, travel time is not the all-important factor. What matters is the ability to slow down and establish orbit around a planet. That way, the spacecraft would be able to seed these nearby worlds with terrestrial organisms, which could have the effect of slowly terraforming it in advance of human explorers or settlers.
Given how long it would take for humans to reach even the nearest extra-solar planets, a mission that last a few hundred or a few thousand years is no big deal. In the end, which method we choose to conduct interstellar mission will come down to how much time we’re willing to invest. For the sake of exploration, expedience is the key factor, which means lightweight craft and incredibly high speeds.
But where long-term goals – such as seeding other worlds with life and even terraforming them for human settlement – are concerned, the slow and steady approach is best. One thing is for sure: when these types of missions move from the concept stage to realization, it sure will be exciting to witness!
