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A Thrilling Trio of Variable Stars

These three variable stars will hold your attention for nights on end.

iStockphotos.com/ZU_09

Tracking variable stars requires meticulous observation habits, with careful attention paid to a single characteristic of a star, its brightness. Many amateur astronomers lean toward observing larger, richer, more detailed, or more colorful deep-sky objects, presuming that monitoring variable stars requires more work or more prolonged effort than they want to put out.

So people may be surprised to learn that three of the greatest amateur astronomers of the 20th century, all widely famed for their interest in more visually rich classes of astronomical objects, all widely treasured for their skilled and beautiful astronomical writing, were devoted, masterful, and passionate observers of variable stars.

Three men and three stars. These three great amateur astronomers are, in chronological order: William Tyler Olcott; Leslie Peltier; and Walter Scott Houston. This is a great time of year to ponder the topic of variable stars and what may have inspired the interest of these men in them. Our current sky offers the best evening visibility for the three most important, prototypical variable stars — all within a few hours of right ascension and within a few constellations of one another. The three variable stars are, west to east: Delta (δ) Cephei, the prototype of the Cepheid variable class; Omicron (ο) Ceti (Mira), the prototype of long-period or Mira variables; and Beta (β) Persei (Algol), the prototype of eclipsing binaries.

Let’s take a closer look at these these three variable stars.

Delta Cephei, Mira, and Algol. I wrote about Delta Cephei in last October’s installment of this column. This pulsating star drops in brightness from magnitude 3.5 to 4.4 and back to maximum in 5 days, 8 hours, and 48 minutes. It forms a small triangle with excellent comparison stars for its maximum and minimum, and it’s also a gorgeous and easy orange and blue double star.

Delta heads a class of variable star known as “the Cepheids,” which offered us a key to establishing distances in the universe. The variability of Delta Cephei was discovered in 1784 by astronomer John Goodricke. Goodricke lost his hearing after falling ill at age 5, but he received a solid education in mathematics and natural philosopy nonethless. He died of pneumonia at the age of 21, but not before proposing the correct explanation for the variability of Algol.

Mira is a long-period variable in the neck of Cetus, the Whale, that goes from one maximum to the next in about 332 days. Mira typically ranges from about 9th or 10th magnitude to 4th or 3rd magnitude, but it occasionally peaks at 2nd magnitude — and once even rivaled 1st-magnitude Aldebaran.

Mira is approximately 500 times the diameter of the Sun and so cool (for a star) that it has water vapor in its outer atmosphere. The star’s variability was first noticed by German pastor David Fabricius back on August 13, 1596, but he seems to have believed it was a nova.

Algol marks the severed head of the monster Medusa in the grasp of Perseus. Algol dims from magnitude 2.1 to 3.4 over a period of 2 days, 20 hours, 48 minutes, and 56 seconds, with both the dimming and brightening taking about 5 hours each. Though Goodricke was the first to figure out Algol dims due to eclipses by its cooler companion star, the variability of Algol seems first to have been recorded by Italian astronomer Geminiano Montanari in 1667.

Next time: the 20th-century three. I’ve only just gestured at the accomplishments of Goodricke, Fabricius, and Montanari this month, but in next month’s column, where we take further looks at awe, total solar eclipses, and more, we’ll also discuss the “20th-century three” mentioned above and their love of variable stars.

This article originally appeared in Sky & Telescope's November 2017 issue.

The post A Thrilling Trio of Variable Stars appeared first on Sky & Telescope.

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napkitores.hu - 2017. november 22. 22:00
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NASA FULL RALLY TODAY.22/11/2017

napkitores.hu - 2017. november 22. 22:00
NASA FULL RALLY TODAY.22/11/2017.

These Streaks on Mars Could be Flowing Sand, not Water

universetoday - 2017. november 22. 20:26

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.

The study, titled “Granular Flows at Recurring Slope Lineae on Mars Indicate a Limited Role for Liquid Water“, recently appeared in the scientific journal Nature Geoscience. Led by Dr. Colin Dundas, of the US Geological Survey’s Astrogeology Science Center, the team also included members from the Lunar and Planetary Laboratory (LPL) at the University of Arizona and Durham University.

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.

As Dundas explained in a recent NASA press release:

“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!

Further Reading: NASA

The post These Streaks on Mars Could be Flowing Sand, not Water appeared first on Universe Today.

The Lost LED Revolution: Light Pollution Is Increasing

skyandtelescope.com-MostRecent - 2017. november 22. 20:00

The transition from sodium lights to LEDs, the so-called “lighting revolution”, was supposed to reduce energy consumption and bring back starry skies, but new satellite data indicate it’s not working out that way.

When scientists are disappointed with their results, it's usually because they were following a different hypothesis than where their data leads. In the case of the switch from sodium lights to LEDs, though, it's more than that.

“Honestly, I had thought, assumed, and hoped that with LEDs we were turning the corner,” says Christopher Kyba (German Research Center for Geosciences). Kyba researches the spread of artificial lights and how it affects our nights, and as a former member of the board of directors of the International Dark Sky Association, he also advocates the use of improved lighting practices.

But in the November 22nd Science Advances, Kyba and colleagues show that we are farther from the goal of dark, starry skies than ever.

World maps showing the rates of change of the lit area of the world (left) and the measured brightness of each country (right) during 2012–2016. Warmer colors in each map correspond to higher rates of change. Note that Australia is an odd case: wildfires increased the country's lit area, but this effect was not included in the radiance analysis.
Kyba et al. / Science Advances

More Lights, Brighter Nights

Outdoor lighting in Doha, Qatar, between 2012 (cyan) and 2016 (red) as seen from the Suomi satellite. Areas newly lit since 2012 appear in bright red.
Kyba et al. / Science Advances

The team used the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on the Suomi National Polar-orbiting Partnership weather satellite to measure the change in global light emissions between October 2012 and October 2016. The VIIRS instrument is the first-ever calibrated satellite radiometer designed to measure nighttime lights – earlier investigations were often based on uncalibrated sensors on military satellites.

VIIRS observes the Day/Night band (DNB), which picks up visible through near-infrared wavelengths. Each pixel covers ½ square kilometer, a higher spatial resolution than previous instruments, which enables scientists to investigate neighborhood-scale changes, rather than city or national, for the first time.

The researchers’ findings will not please astronomers: Earth’s nights are becoming brighter.

Between 2012 and 2016, the artificially lit outdoor area on our planet grew by 9.1%, an annual increase of roughly 2.2%. Additionally, already lit areas also got brighter by 2.2% per year. Only very few places show a decrease in lighting (mostly war-torn countries like Syria and Yemen), while some of the already brightest-lit countries remained stable, among them Spain, Italy and the United States. With few exceptions, all countries in Asia, Africa, and South America emit significantly more light now than they used to five years ago.

That in itself isn’t unexpected — artificial lighting has long been an indicator for growing wealth and population. What’s surprising is that the ongoing transition to LEDs isn’t having a contrary effect.

“While we know that LEDs save energy in specific projects, for example when a city transitions all of its street lighting from sodium lamps to LED,” Kyba explains, “when we look at our data at the national and the global level, it indicates that these savings are being offset by either new or brighter lights in other places.”

Changes in the color of Milan, Italy, at night between 2012 (left) and 2015 (right), between which the outdoor lighting in its urban core was transitioned from high-pressure sodium vapor to white LED.
International Dark-Sky Association / NASA

It's a rebound effect: Cheaper lights lead not to savings in energy consumption, but to more light. And that’s not just bad news for astronomers.

“Since the first emergence of life, the biological world was organized to a large extent by natural cycles of variation in light,” explains Franz Hölker (Leibniz Institute of Freshwater Ecology and Inland Fisheries, Germany). “From an evolutionary perspective, artificial light at night is a very new stressor.”

Because electricity brings light to places, times, and intensities at which it doesn’t naturally occur, many organisms have no chance to adapt. Their natural light cycles are fundamentally disrupted. About 30% of vertebrates and more than 60% of invertebrates on our planet are nocturnal, but outdoor artificial light also affects plants and microorganisms, and scientist are only beginning to learn about its possible negative effects on human health.

Blue vs. Amber LEDs

To make matters worse, the DNB is insensitive to wavelengths below 0.5 microns — blue light, which the atmosphere scatters more than other visible wavelengths. Unfortunately, many popular LED lights peak at these wavelengths.

It doesn’t have to be this way. “One of the really huge advantages of LEDs is that it’s possible to make very many different colors,” Kyba insists. “Cities can buy lamps that are not white, that have this blue component completely removed.” However these “PC Amber” or “True Amber” lights are so far used almost exclusively in designated dark-sky places.

Nevertheless, Kyba and his colleagues remain open to working with cities, local governments, and industry partners to reverse this trend: “The real dream is that we have great vision on the streets, never really experience an uncomfortably dark place inside of a city, but because the light is used much more efficiently, would have more stars to see in the sky.”

Find more information and resources for local change in Sky & Telescope's Saving Dark Skies section.

The post The Lost LED Revolution: Light Pollution Is Increasing appeared first on Sky & Telescope.

How the Earth stops high-energy neutrinos in their tracks

sciencedaily.com - 2017. november 22. 19:13
For the first time, a science experiment has measured Earth's ability to absorb neutrinos -- the smaller-than-an-atom particles that zoom throughout space and through us by the trillions every second at nearly the speed of light. The experiment was achieved with the IceCube detector, an array of 5,160 basketball-sized sensors frozen deep within a cubic kilometer of very clear ice near the South Pole.

Lightning, with a chance of antimatter

sciencedaily.com - 2017. november 22. 19:13
Researchers find that lightning strikes causes photonuclear reactions in the atmosphere, creating antimatter.

Frictional heat powers hydrothermal activity on Enceladus

sciencedaily.com - 2017. november 22. 18:59
A computer simulation shows how icy moon heats water in a porous rock core. This study also offers among others an answer to the long-standing question of where the energy that can support water in liquid form on a small, cryovulcanic moon far from the sun comes from.

Galactic Panspermia: Interstellar Dust Could Transport Life from Star to Star

universetoday - 2017. november 22. 18:56

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.

Further Reading: University of Edinburgh, Astrobiology

The post Galactic Panspermia: Interstellar Dust Could Transport Life from Star to Star appeared first on Universe Today.

Weekly Space Hangout – Nov. 22, 2017: Andy Weir and ARTEMIS

universetoday - 2017. november 22. 18:50

Hosts:
Fraser Cain (universetoday.com / @fcain)
Dr. Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Dr. Kimberly Cartier (KimberlyCartier.org / @AstroKimCartier )
Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg ChartYourWorld.org)

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.

You can learn more about Andy and his books on his website (http://andyweirauthor.com)!

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 giveaways@wshcrew.space 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.

On a side note, THIS awesomeness based on Dean’s FIRST book is now also available:
» 365 Facts from Space! 2018 Daily Calendar

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!

The post Weekly Space Hangout – Nov. 22, 2017: Andy Weir and ARTEMIS appeared first on Universe Today.

Dark matter and dark energy: Do they really exist?

sciencedaily.com - 2017. november 22. 17:30
Researchers have hypothesized that the universe contains a 'dark matter.' They have also posited the existence of a 'dark energy.' These two hypotheses account for the movement of stars in galaxies and for the accelerating expansion of the universe. But, according to a researcher, these concepts may be no longer valid: the phenomena can be demonstrated without them. This research exploits a new theoretical model based on the scale invariance of the empty space.

New method to measure neutron star size uses modeling based on thermonuclear explosions

sciencedaily.com - 2017. november 22. 17:30
Neutron stars are made out of cold ultra-dense matter. How this matter behaves is one of the biggest mysteries in modern nuclear physics. Researchers developed a new method for measuring the radius of neutron stars which helps them to understand what happens to the matter inside the star under extreme pressure.

Invite Ross 128 Over This Thanksgiving

skyandtelescope.com-MostRecent - 2017. november 22. 16:30

With exoplanet Ross 128b in the news, we pay a visit to the star that sustains this potentially habitable exoplanet. 

The red dwarf, Ross 128, hosts the temperate, Earth-sized planet Ross 128 b. The star is about 20% of the Sun's diameter and 17% as massive.
Sloan Digital Sky Survey

No matter where you look the fecundity of the universe is manifest. Consider exoplanets. Since the first was discovered in 1992, astronomers have been piling them on like mashed potatoes at Thanksgiving. Today we know of more than 3,700. Of those, 53 may be potentially habitable.

The most recently discovered potentially life-friendly planet — and in some ways the most exciting — is Ross 128b, which circles the red dwarf star Ross 128 in the constellation Virgo. Located just 11 light-years away, it's the second closest Earth-sized planet within the habitable zone of its star.

Astronomers estimate that temperatures on Ross 128b range from  –76° to 68° F (–60° to 20° C). You could argue that's even more temperate than than that of Earth and likely warm enough for liquid water to pool on its surface. What's more, its star experiences far fewer massive flares compared to other red dwarfs, making conditions more hospitable to potential life.

If you have a 4.5-inch or larger telescope, you can track down Ross 128 in Virgo in the morning sky. Place Beta (β) Virginis in the field of a low-power eyepiece and you're halfway there! Mars's location is shown for November 21st.
Stellarium

While you and I aren't going to see Ross 128b anytime soon, we can have the pleasure of seeing its host sun, Ross 128. Currently visible in a dark sky before the start of dawn, this newsy red dwarf is just 1.1° southwest of 3rd-magnitude Beta (β) Virginis. To find the dwarf and its mind's-eye planet, center Beta in the field of view and use the AAVSO map to star-hop right to it.

Once Beta (β) Vir is in the field of view, use this chart from the American Association. of Variable Star Observers to star-hop to Ross 128, also known as the variable star FI Virginis. Numbers are stellar magnitudes with the decimals omitted, so 107 = 10.7. North is up.
AAVSO with annotations by the author

Eager to see it for myself, I got up the first clear morning after the news of the discovery broke last week. Oh gosh, how easy could it be. Pale red and magnitude 11.2, Ross 128 is bright enough to spot in telescopes as small as 4 inches (10 cm). Mingled in the star's light were photons from its closely orbiting and perhaps habitable planet, a satisfying thought.

Some 80% of the Milky Way's stars are red dwarfs, yet not a single one is visible to the naked eye. Being something of an introvert, I cotton to these shy suns. The brightest, Lacaille 8760 in Microscopium, shines at magnitude 6.7. Despite their retiring nature, they make for fertile exoplanet hunting grounds. A tiny dwarf feels a much stronger — and more easily measurable — tug by an orbiting planet compared to a bigger star like our Sun.

This graph shows how the distances of several nearby stars change over a period from 20,000 years in the past to 80,000 years in the future. “0” is the current time; distances are given in light years. Ross 128 is closing in, as is Alpha Centauri. Around the year 25,000 AD, the Alpha Centauri system will be just 3 light-years from Earth.
FrancescoA / CC SA-3.0

If we're patient and smart enough not to destroy ourselves, we'll have an even better view of Ross 128 in due time. The star is moving towards us at 31 km/sec and will become our nearest stellar neighbor around 81,000 AD, when only 6.2 light-years will separate the two Earths.

We celebrate Thanksgiving this week, a time to be grateful for all we have. As we reflect on the ups and downs that sustain our lives, feel free to take another helping at the table, including this stellar cranberry.

The post Invite Ross 128 Over This Thanksgiving appeared first on Sky & Telescope.

Gifts for the Astronomer: Top Editors’ Picks

skyandtelescope.com-MostRecent - 2017. november 22. 15:00

Searching for that perfect astronomy-themed gift for a friend or loved one? Look no further, we've got you covered, with globes, atlases, calendars, and much more!

Top 5 Editors' Picks 1. Celestial Globe ($99.95)

This 12-inch freestanding globe allows you to explore the stars with an “inside-out” perspective that closely matches what you see in the night sky.

This globe isn't just beautiful; it's incredibly detailed, plotting 2,934 stars down to magnitude 5.5, with more than 300 common star names, 550 Bayer star designations, and double and variable stars indicated. You'll find deep-sky objects, too, from the Messier and Caldwell catalogs.

Created by Sky & Telescope and manufactured by Replogle, you won't find anything quite like this globe anywhere else.

2. Sky Atlas 2000.0 Deluxe Edition ($95.96)

Associate Editor JR writes: "Every amateur astronomer has a “go-to” atlas, and the laminated version of Sky Atlas 2000.0 is mine – it goes everywhere my scope goes. I prefer to use these high-contrast, black-and-white charts out in the field so I can keep my red light use to a minimum, and the large scale makes it easy to see where I am at a glance. The charts go to magnitude 8.5, which gives me enough signposts to find my way to pretty much any target I seek.

"The atlas’s laminated pages are designed to be durable and dew resistant, but that plastic coating offers another benefit: I can write directly on the smooth pages with white wax china marker, which makes it even easier to keep track during complicated star hops. A napkin cleans my scribbled notes right off.

"The atlas comes with a transparent sheet for assistance in gauging RA and Dec. More importantly, the sheet has a circle mimicking the field of view of a Telrad finder, making it even easier to match the eyepiece view to what’s on the page."

3. Moon & Mars Globes ($99.99 each)

Have you wanted to step foot on Mars since you were little? Do you gaze at the Moon through your telescope and marvel at its craters and maria?

Now you can hold these worlds in your hands, examining their details as photographed from orbit at high resolution. Find the rover landing sites, trace the path taken by Mark Watney in The Martian (yes, we've done that), or help make sense of the view you're seeing through your telescope.

These 12-inch globes make perfect additions to any study or observatory.

4. 2018 Calendar Bundle ($24.99)

Whether you keep one, keep both, or give them away as the perfect gifts for the observing and science enthusiasts in your life, this bundle provides a great value. The Observing Calendar serves as a handy reference for the observatory wall, while the Incredible Cosmos calendar gives a daily dose of cosmic perspective from your desk.

The Observing Calendar helps plan out your week — it reminds you of every major observing event of the year, gives almanac-like information on the visibility of the planets, and every month is accompanied by a beautiful image. The best part: a monthly sky scene tucked in the corner shows a clear at-a-glance guide to the naked-eye sky.

The Incredible Cosmos calendar provides a daily reminder of how literally awesome our universe is. Every day teaches you something, whether it's about the worlds of the Moon, Mars, and Titan; the nature of dark matter and dark energy; or how black holes work. And there's a treat every Friday: a full-color image from our strange and wonderful cosmos.

5. Binocular Highlights, 2nd Edition ($24.99)

News Editor Monica Young writes, "You know what they say: The best first telescope is a pair of binoculars. The reason? Binoculars give the beginner the chance to explore the night sky in more detail without losing yourself among the thousands of scattered stars. Even for the veteran observer, binoculars offer you a chance to discover jewels you might miss in the narrower fields of view that telescopes offer.

"Binocular Highlights, the second edition of a long-time favorite, will guide you to those celestial jewels. I find it easy to select targets for the night, as the book is conveniently divided by season, and easy-to-use charts guide me to each object. Author Gary Seronik fills out each entry with additional advice, such as what is ok to see from light-polluted skies (such as those of my backyard) and what is better seen from darker locations.

"On a related note, the book is compact enough that it becomes an easy carry-on — along with your binos — for any trip."

Make sure you take advantage of our Black Friday and Cyber Monday deals!

For November 24 - 27:

  • Take 50% off store-wide (excludes non-discountables and globes)
  • Take 20% off Globes
  • Take an extra 10% off the Value Bundles category using code BFKITS10

For November 27 only:

  • Free Shipping store-wide with code: CYBERSHIP
Stocking Stuffers

These smaller and affordably priced products are incredibly useful — and beautiful — items for the astronomy enthusiast in your life.

  1. 15-cm Globes ($24.99 each) - Hold Earth, the Moon, and Mars in one hand — these picturesque globes depict our favorite worlds at a smaller (and more affordable) size.
  2. SkyWatch 2018 ($8.99) - Whether you're just starting out or an experienced observer, you'll find this year-long guide to the night sky indispensable.
  3. Skygazer's Almanac Wall Poster ($15.99) - This at-a-glance guide to the sky shows you what's happening tonight: when does the Sun set, when does the Moon rise, when are your favorite planets up. It even marks major events, such as occultations, meteor showers and eclipses.
  4. Planisphere ($15.95) - The perfect introduction to constellations all year round, created for night skies at latitudes 30°N, 40°N, 50°N, and 30°S.
  5. Messier Card ($6.95) - This 9x12-inch laminated quick-reference guide will come in handy for March Messier Marathons, or anytime you're looking for deep-sky inspiration.

Visit ShopatSky for more gift ideas!

The post Gifts for the Astronomer: Top Editors’ Picks appeared first on Sky & Telescope.

SpaceX Resuming Launches from Damaged Pad 40 on Dec. 4 with Station Resupply Flight for NASA; Covert Zuma Remains on Hold

universetoday - 2017. november 21. 20:48

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

KENNEDY SPACE CENTER, FL – After postponing last week’s liftoff of the covert ‘Zuma’ spy satellite due to last minute concerns about the reliability of the payload fairing encapsulating it while poised for liftoff at KSC pad 39, SpaceX is set to at last resume launches from their previously damaged and now repaired Cape Canaveral pad 40 with a cargo resupply mission for NASA to the International Space Station (ISS) on Dec 4.

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 engineers also had to deal with the after effects of a fire that broke out on a Merlin engine test stand during preparations for a hot fire test that resulted from a leak during a ‘LOX drop’ that halted testing of the Block 5 version of the Merlin 1D.

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.

The Dec. 4 launch date for Dragon CRS-13 was announced by NASA’s space station manager Dan Hartman during the Orbital ATK Antares/Cygnus launch campaign that culminated with a successful blastoff last Sunday, Nov 12 from NASA’s Wallops Flight Facility on Virginia’s eastern shore.

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.

Meanwhile SpaceX wants to upgrade pad 39A to launch the Falcon Heavy and crewed Dragon flight. But those launches cant take place until pad 40 resumes operational status.

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.

Ken Kremer

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.com

SpaceX 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

The post SpaceX Resuming Launches from Damaged Pad 40 on Dec. 4 with Station Resupply Flight for NASA; Covert Zuma Remains on Hold appeared first on Universe Today.

NASA Joins Japanese Mission to Martian Moons

skyandtelescope.com-MostRecent - 2017. november 21. 20:48

NASA is developing a key instrument for a daring mission to the Martian moons, Phobos and Deimos, including a sample return from Phobos.

An artist's conception of MMX at a Martian moon
JAXA / NASA

Amid the flurry of missions set to head towards Mars during the next few launch windows, there's one ambitious plan to go where no spacecraft has gone before: the Martian moons.

NASA recently announced it will join the Japanese Aerospace Exploration Agency  (JAXA) and the Institute of Space and Aeronautical Science (ISAS), contributing a crucial instrument to the Mars Moons eXploration (MMX) mission.

Set for launch in 2024, MMX will explore the tiny Martian moons Phobos and Deimos close up, then touch down on Phobos for a sample collection for return to Earth. The sample return capsule will then arrive back on Earth with its precious cargo in 2029.

Meet MEGANE

NASA's contribution to the MMX mission is MEGANE, the Mars moon Exploration with GAmma-rays and NEutrons instrument, a sophisticated spectrograph. “Megane,” pronounced meh-gah-nay, also means “eyeglasses” in Japanese.

MEGANE will analyze the elemental composition of Phobos and Deimos based on measurements of the cosmic rays and solar particles that continually bombard the two moons's surfaces.

“We'll see the composition of the region from which MMX collects its sample,” says Thomas Statler (NASA HQ) in a recent press release. “This will help us better understand what we discover in the laboratory when the mission returns the sample to Earth for analysis.”

MEGANE will be devloped under NASA's Discovery Program, which provides low-cost access to space on planetary science missions.

The MMX spacecraft
ISAS / JAXA

The primary goal of the MMX mission is to understand the origin of the Martian moons — are they captured asteroids or material left over from an ancient impact on Mars? A secondary goal is to characterize the global dynamics of the Martian atmosphere and the orbital environment the moons occupy.

Due to the moons' suspected origins, a sample return might even return a piece of Mars itself. Both moons also probably get pelted by ejecta from Mars impacts from time to time, so there's a good chance that MMX could find a Martian rock on Phobos's surface.

The Strange Worlds of Phobos and Deimos

Astronomer Asaph Hall discovered Phobos and Deimos in 1877 using the U.S. Naval Observatory's 26-inch refractor during a favorable opposition. Deimos, a small rock just 13 kilometers (8 miles) across, orbits Mars every 30 hours at a respectable distance of 23,460 kilometers.

Phobos, on the other hand, is the larger, closer, and quicker of the pair. It circles Mars every 7.7 hours, even faster than it rotates, which means that Mars actually rises in the west and sets in the east from the moon's perspective. No moon in the solar system hugs its planet as close as Phobos, which orbits just 6,000 kilometers above the Martian surface. Its close orbit is just one clue of what recent research has shown: Phobos is a doomed world, destined to either disintegrate into a ring or smash into the surface of Mars in 30 million to 50 million years. The fate of the more distant Deimos is less clear.

A Mars Express image of rocky Phobos shows grooves, which may be due to tidal stress already stretching out the interior of the close moon.
ESA

Curious theories for how these strange moons arose go back to the early Space Age. In 1958 Russian astrophysicist Iosif Samuilovich Shklovsky proposed that the moons might actually be hollowed-out space stations! Surprisingly, this claim gained traction in fringe circles, despite a hoax perpetrated by Sky & Telescope contributor Walter Scott Hudson, who claimed the same as a parody on April Fool's Day the following year.

NASA's Mars Reconnaissance orbiter imaged outermost Deimos in 2008.
NASA / JPL-Caltech / University of Arizona

We obtained our first good looks at the two moons starting with Mariner 7 in 1969, followed by  the Viking missions in the 1970s. These close-ups revealed natural, rocky worlds, featuring long grooves along their surfaces, which are also pockmarked with craters. The European Space Agency's Mars Express, India's Mars Orbiter Mission and NASA's Mars Reconnaissance Orbiter have all imaged the moons during flybys.

Curiosity has even imaged the moons from the surface of Mars, as they complete strange potato-shaped annular eclipses in front of the Sun (see below). All of these observations have enabled astronomers to refine the orbits of Phobos and Deimos with greater precision.

Curiosity nabs a unique "Phobos eclipse."
NASA / JPL-Caltech/Malin Space Science Systems / Texas A&M University

A landing on Phobos would be a first, but it would actually be easier than landing on Mars itself due to the moon's negligible surface gravity.

Humans have tried to visit the Martian moons before: NASA proposed a mission named the Phobos and Deimos Mars Environment explorer (PADME) in 2014, but it lost to Psyche and Lucy for Discovery Program funding. The Russians also attempted a sample return mission mission named Phobos-Grunt in 2011, but it failed to leave Earth orbit and re-entered over the South Pacific on January 15, 2012.

Though it's unclear whether Russia will attempt another mission like Phobos-Grunt, Roscosmos did contribute hardware to the ExoMars Trace Gas Orbiter and failed EDM Schiaparelli lander, and the country's contributions will also play a role in ESA's ExoMars Rover, set to launch in July 2020.

To date, JAXA has only attempted one mission to Mars: the ill-fated Nozomi mission, which failed to enter orbit around the Red Planet in 2003 due to a malfunctioning valve, which resulted in insufficient fuel for braking. However, JAXA does have experience with sample returns from the Hayabusa 1 mission to 25143 Itokawa, as well as Hayabusa 2, which is set to arrive at 162173 Ryugu in June 2018.

Interest in Mars is sure to spike next summer as we head towards an opposition on July 27, 2018 that's nearly as favorable as the historic 2003 passage. This time will also present an ideal opportunity to hunt for the moons through your eyepiece. The trick is knowing when the moons will be at greatest elongation and hiding dazzling Mars just out of view or behind an occulting bar eyepiece.

Seeing Edgar Rice Burrough's “hurtling moons of Barsoom” for yourself is a thrill, and a mission to explore Phobos and Deimos will surely be an epic odyssey of exploration.

The post NASA Joins Japanese Mission to Martian Moons appeared first on Sky & Telescope.

Could Magnetic Sails Slow an Interstellar Spacecraft Enough?

universetoday - 2017. november 21. 20:07

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!

Further Reading: Goete University Frankfurt, Journal of Physics Communications

The post Could Magnetic Sails Slow an Interstellar Spacecraft Enough? appeared first on Universe Today.

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