Posted on by Matt Williams

Culprit Found In Blurry Astronaut Vision Mystery

Astronauts Kate Rubins (left) and Jeff Williams (right) looking out of the ISS' cupola at a SpaceX Dragon supply spacecraft. Until recently, the effects of long-duration missions on eyesight was something of a mystery. Credit: NASA

The ability to take part in long-term space missions is a rare privilege, usually enjoyed by only a handful of men and women within every generation. But that privilege comes with a pretty high price. In addition to all the hard work, training, and sacrifice that is needed to go into space, there are also the health effects of spending prolonged periods in a microgravity environment.

Until recently, the most well-document of these effects were muscle degeneration and loss of bone density. But thanks to a new study released by the Radiological Society of America, it is now understood how microgravity can impair eyesight. This is certainly good news for ISS crews, not to mention the astronauts who will be taking part in long-range missions to Mars and beyond in the near future.

For years, NASA and other space agencies have been seeking to understand how time in space can adversely affect eyesight. Nearly two-thirds of astronauts who have taken part in long-duration missions aboard the International Space Station (ISS) have been diagnosed with Visual Impairment Intracranial Pressure (VIIP) syndrome. Symptoms include blurred vision, flattening at the back of eyeballs, and inflammation of the head of the optic nerves.

Expedition 46 Commander Scott Kelly of NASA rests in a chair outside of the Soyuz TMA-18M spacecraft just minutes after he and cosmonauts Mikhail Kornienko and Sergey Volkov of the Russian space agency Roscosmos landed in a remote area near the town of Zhezkazgan, Kazakhstan late Tuesday, March 1 EST. Credits: NASA/Bill Ingalls
Expedition 46 Commander Scott Kelly of NASA resting after returning to Earth in March, 2016. At the time, Kelly established the record for longest time spent in space. Credits: NASA/Bill Ingalls

Previously, scientists believed that the primary source of VIIP was a shift of vascular fluid toward the upper body that takes place when astronauts spend time in the microgravity of space. But thanks to the new study, which was led by Dr. Noam Alperin and his team of researchers from the University of Miami, the cause of the syndrome has been properly diagnosed.

Dr. Alperin is a professor of radiology and biomedical engineering at the Miller School of Medicine at the University of Miami and the lead author of the study. According to the study he and his colleagues produced – which was presented on Monday, Nov. 28th, at the annual meeting of the Radiological Society of North America in Chicago – the culprit is cerebrospinal fluid (CSF).

This clear fluid is chiefly responsible for cushioning the brain and spinal cord, circulating nutrients and removing waste materials. At the same time, the CSF system is designed to accommodate significant changes in hydrostatic pressures, like when a person goes from lying down or sitting to a standing position. However, this system evolved within Earth’s own gravity environment, and exposing it to microgravity presents unique challenges.

As Dr. Alperin explained in a RSNA press statement, which coincided with the annual meeting:

“People initially didn’t know what to make of it, and by 2010 there was growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to Earth. On earth, the CSF system is built to accommodate these pressure changes, but in space the system is confused by the lack of the posture-related pressure changes.”

Astronaut Jeff Williams just established a new record for most time spent in space by a NASA astronaut. Credit: NASA
Astronaut Jeff Williams, who recently broke Kelly’s record for most time spent in space by a NASA astronaut. Credit: NASA

To arrive at this conclusion, Dr. Alperin and his colleague performed a series of before and after MRI scans on seven astronauts who took part in long-duration missions aboard the ISS. The results were compared against nine astronauts who took part in short-duration missions aboard the now-retired Space Shuttle. With the help of some special imaging algorithms, they looked for correlations between changes in CSF volumes and VIIP.

The results of their study Their study, titled “Role of Cerebrospinal Fluid in Spaceflight-Induced Visual Impairment and Ocular Changes“, showed that astronauts who participated in long-duration missions experienced a comparably higher flattening of their eyeballs and protrusions in their optic nerves. These astronauts also had significantly higher post-flight increases in CSF around their optic nerves and in the cavities of the brain where CSF is produced.

This study is both timely and significant, given the growing important of long-duration space missions. At present, it is expected that operations aboard the ISS will last for another decade. One of the most important activities there will be the study of the long-term effects of microgravity on human physiology, which will be intrinsic to preparing astronauts for missions to Mars and other long-range destinations.

Magnetic-resonance (MR) image of an eye before and after a long-duration space flight. Credit: RSNA
Magnetic-resonance (MR) image of an astronauts eye before and after a long-duration space flight. Credit: RSNA

In short, identifying the origin of the space-induced ocular changes will help NASA and other space agencies to develop the proper countermeasures to protect the crew from potentially harmful changes to their eyesight. It will also come in handy for private space ventures that are hoping to send human beings on one-way trips to locations where the gravity is lower than on Earth (i.e. the Moon and Mars).

“The research provides, for the first time, quantitative evidence obtained from short- and long-duration astronauts pointing to the primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome,” said Alperin. If the ocular structural deformations are not identified early, astronauts could suffer irreversible damage. As the eye globe becomes more flattened, the astronauts become hyperopic, or far-sighted.”

As the old saying goes, “an ounce of prevention is worth a pound of cure”. In addition to having regiments that will help maintain their musculature and bone density, astronauts taking part in long-term missions in the future will also likely need to undergo treatments to ensure their eyesight doesn’t suffer.

Further Reading: RSNA

Posted on by Nancy Atkinson

‘Spectacular’ First Images and Data Released from ExoMars Orbiter

One of the first images from the Mars Camera, CaSSIS, on the ExoMars Trace Gas Orbiter. The image shows a 1.4 km sized crater (left center) on the rim of a much larger crater near the Mars equator. Credit: ESA/Roscosmos/ExoMars/CaSSIS/UniBE.

The first images taken by the newest mission to Mars have been released, and the teams behind the instruments on ESA’s ExoMars Trace Gas Orbiter are ecstatic.

“The first images we received are absolutely spectacular – and it was only meant to be a test,” said Nicolas Thomas, who leads the Colour and Stereo Surface Imaging System at the University of Bern.

The ExoMars TGO arrived in orbit at Mars over a month ago, on October 19, 2016 along with the Schiaparelli lander, which unfortunately crashed on the surface of Mars.

“A lot of public attention has been on the failed landing of Schiaparelli,” said Thomas, “but TGO has been working really well so we have been extremely busy in the past month.”

Scientists and engineers have been turning on and checking out the various instruments on TGO as it orbits in an initial elliptical orbit that takes it from just 250 km above the surface of Mars to nearly 100,000 km every 4.2 days.

During November 20-28 it spent two orbits testing its four science instruments for the first time and making important calibration measurements. A total of 11 images were returned during the first close fly-by during that period, which you can see in the video below.

The views show Hebes Chasma, an 8 km-deep trough in the northern most part of Valles Marineris, during the spacecraft’s closest approach.

“We saw Hebes Chasma at 2.8 metres per pixel” Thomas said. “That’s a bit like flying over Bern at 15,000 km per hour and simultaneously getting sharp pictures of cars in Zurich.”

The first stereo reconstruction of a small area in Noctis Labyrinthus. The image gives an altitude map of the region with a resolution of less than 20 meters. Credit: ESA/Roscosmos/ExoMars/CaSSIS/UniBE
The first stereo reconstruction of a small area in Noctis Labyrinthus. The image gives an altitude map of the region with a resolution of less than 20 meters. Credit: ESA/Roscosmos/ExoMars/CaSSIS/UniBE

The team tested the color and stereo capabilities of CaSSIS were also successfully tested. Below is a 3D reconstruction of a region called Noctis Labyrinthus that was produced from a stereo pair of images. This region is also part of Valles Marineris and has a system of deep, steep-walled valleys.

Thomas said these first images don’t show much color because the surfaces in this area are covered with dust so there are few color changes evident. “We will have to wait a little until something colourful passes under the spacecraft,” he said. Until then, the pictures will be black and white.

The ExoMars 2016 mission is a collaboration between the European Space Agency (ESA) and Roscosmos. ExoMars will continue the search for biological and geologic activity on Mars, which may have had a much warmer, wetter climate in the past. The TGO orbiter is equipped with a payload of four science instruments supplied by European and Russian scientists that will investigate the source and precisely measure the quantity of the methane and other trace gases.

Methane provides the most interest because it has been detected periodically on Mars. On Earth, methane is produced primarily by biological activity, and to a smaller extent by geological processes such as some hydrothermal reactions.

First detection of atmospheric carbon dioxide by the ExoMars Trace Gas Orbiter’s Atmospheric Chemistry Suite. Credit: ESA/Roscosmos/ExoMars/ACS/IKI.
First detection of atmospheric carbon dioxide by the ExoMars Trace Gas Orbiter’s Atmospheric Chemistry Suite. Credit: ESA/Roscosmos/ExoMars/ACS/IKI.

The two instruments that will be used to look for methane and other gases were also tested. During the test observations last week, the Atmospheric Chemistry Suite focused on carbon dioxide, which makes up a large volume of the planet’s atmosphere, while the Nadir and Occultation for Mars Discovery instrument looked for water.

The teams also coordinated observations with ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter, as they will do future corresponding observations during the mission.

Starting in March, 2017, TGO will use Mars atmosphere to perform aerobraking to gradually slow the spacecraft down to reach a roughly circular orbit 400 km above Mars. The aerobraking process will take between 9-12 months, with the primary science phase will beginning near the end of 2017.

The CaSSIS camera team said nominal operations will have the instrument acquiring 12-20 high resolution stereo and color images of selected targets per day.

Sources: ESA, University of Bern.

Posted on by Evan Gough

Sentinel-1 Satellites Confirm San Francisco’s Millenium Tower Is Sinking

The Millennium Tower luxury skyscraper in San Francisco is sinking and tilting. Image by MichaelTG - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=51657571

The Millennium Tower is a luxury skyscraper in San Francisco. It has been sinking and tilting since it’s construction 8 years ago. In fact, the 58 story building has sunk 8 inches, and tilted at least 2 inches. San Francisco is experiencing a building boom, and planners and politicians want to know why the Millennium Tower is having these problems.

Now they’re getting a little help from space.

The European Space Agency’s (ESA) Copernicus Sentinel-1 satellites have trained their radar on San Francisco. They’ve found that the Millennium Tower is sinking, or subsiding, at the alarming rate of almost 50 mm per year. Although the exact cause is not yet known for sure, it’s suspected that the building’s supporting piles are not resting on solid bedrock.

An artist's illustration of the Sentinel-1. Image: ESA/ATG Medialab
An artist’s illustration of the Sentinel-1. Image: ESA/ATG Medialab

The Sentinel-1 satellites are part of the ESA’s Copernicus Program. There are two of the satellites in operation, and two more are on the way. They employ Synthetic Aperture Radar to provide continuous imagery during the day, during the night, and through any kind of weather.

The satellites have several applications:

  • Monitoring sea ice in the arctic
  • Monitoring the arctic environment and other marine environments
  • Monitoring land surface motion
  • Mapping land surfaces, including forest, water, and soil
  • Mapping in support of humanitarian aid in crisis situations

Though the Sentinels were not specifically designed to monitor buildings, they’re actually pretty good at it. Buildings like the Millennium Tower are especially good at reflecting radar. When multiple passes are made with the satellites, they provide a very accurate measurement of ground subsidence.

Radar data from Sentinel-1 shows the displacement in San Francisco's Bay Area. Yellow-red areas are sinking, while blue areas are rising. Green areas are not moving. Image: ESA SEOM INSARAP study / PPO.labs / Norut / NGU
Radar data from Sentinel-1 shows the displacement in San Francisco’s Bay Area. Yellow-red areas are sinking, while blue areas are rising. Green areas are not moving. Image: ESA SEOM INSARAP study / PPO.labs / Norut / NGU

The Millennium Tower is not the only thing in San Francisco Bay Area that Sentinel-1 can see moving. It’s also spotted movement in buildings along the Hayward Fault, an area prone to earthquakes, and the sinking of reclaimed land in San Rafael Bay. It’s also spotted some rising land near the city of Pleasanton. The recent replenishing of groundwater is thought to be the cause of the rising land.

Now other parts of the world, especially in Europe, are poised to benefit from Sentinel-1’s newfound prowess at reading the ground. In Oslo, Norway, the train station is built on reclaimed land. Newer buildings have proper foundations right on solid bedrock, but the older parts of the station are experiencing severe subsidence.

Sentinel-1 data shows that the Oslo train station, the red/yellow area in the center of the image, is sinking at the rate of 12-18mm per year. Image: Copernicus Sentinel data (2014–16) / ESA SEOM INSARAP study / InSAR Norway project / NGU / Norut / PPO.labs
Sentinel-1 data shows that the Oslo train station, the red/yellow area in the center of the image, is sinking at the rate of 12-18mm per year. Image: Copernicus Sentinel data (2014–16) / ESA SEOM INSARAP study / InSAR Norway project / NGU / Norut / PPO.labs

John Dehls is from the Geological Survey of Norway. He had this to say about Sentinel: “Experience and knowledge gained within the ESA’s Scientific Exploitation of Operational Missions programme give us strong confidence that Sentinel-1 will be a highly versatile and reliable platform for operational deformation monitoring in Norway, and worldwide.”

As for the Millennium Tower in San Francisco, the problems continue. The developer of the building is blaming the problems on the construction of a new transit center for the city. But the agency in charge of that, the Transbay Joint Powers Authority, denies that they are at fault. They blame the developer’s poor structural design, saying that it’s not properly built on bedrock.

Now, the whole thing is before the courts. A $500 million class-action lawsuit has been filed on behalf of the residents, against the developer, the transit authority, and other parties.

It’s a good bet that data from the Sentinel satellites will be part of the evidence in that lawsuit.

Posted on by Matt Williams

What is a Supermassive Black Hole?

Detection of an unusually bright X-Ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy. Credit: NASA/CXC/Stanford/I. Zhuravleva et al.

In 1971, English astronomers Donald Lynden-Bell and Martin Rees hypothesized that a supermassive black hole (SMBH) resides at the center of our Milky Way Galaxy. This was based on their work with radio galaxies, which showed that the massive amounts of energy radiated by these objects was due to gas and matter being accreted onto a black hole at their center.

By 1974, the first evidence for this SMBH was found when astronomers detected a massive radio source coming from the center of our galaxy. This region, which they named Sagittarius A*, is over 10 million times as massive as our own Sun. Since its discovery, astronomers have found evidence that there are supermassive black holes at the centers of most spiral and elliptical galaxies in the observable Universe.

Description:

Supermassive black holes (SMBH) are distinct from lower-mass black holes in a number of ways. For starters, since SMBH have a much higher mass than smaller black holes, they also have a lower average density. This is due to the fact that with all spherical objects, volume is directly proportional to the cube of the radius, while the minimum density of a black hole is inversely proportional to the square of the mass.

In addition, the tidal forces in the vicinity of the event horizon are significantly weaker for massive black holes. As with density, the tidal force on a body at the event horizon is inversely proportional to the square of the mass. As such, an object would not experience significant tidal force until it was very deep into the black hole.

Formation:

How SMBHs are formed remains the subject of much scholarly debate. Astrophysicists largely believe that they are the result of black hole mergers and the accretion of matter. But where the “seeds” (i.e. progenitors) of these black holes came from is where disagreement occurs. Currently, the most obvious hypothesis is that they are the remnants of several massive stars that exploded, which were formed by the accretion of matter in the galactic center.

Another theory is that before the first stars formed in our galaxy, a large gas cloud collapsed into a “qausi-star” that became unstable to radial perturbations. It then turned into a black hole of about 20 Solar Masses without the need for a supernova explosion. Over time, it rapidly accreted mass in order to become an intermediate, and then supermassive, black hole.

In yet another model, a dense stellar cluster experienced core-collapse as the as a result of velocity dispersion in its core, which happened at relativistic speeds due to negative heat capacity. Last, there is the theory that primordial black holes may have been produced directly by external pressure immediately after the Big Bang. These and other theories remain theoretical for the time being.

Sagittarius A*:

Multiple lines of evidence point towards the existence of a SMBH at the center of our galaxy. While no direct observations have been made of Sagittarius A*, its presence has been inferred from the influence it has on surrounding objects. The most notable of these is S2, a star that flows an elliptical orbit around the Sagittarius A* radio source.

S2 has an orbital period of 15.2 years and reaches a minimal distance of 18 billion km (11.18 billion mi, 120 AU) from the center of the central object. Only a supermassive object could account for this, since no other cause can be discerned. And from the orbital parameters of S2, astronomers have been able to produce estimates on the size and mass of the object.

For instance, S2s motions have led astronomers to calculated that the object at the center of its orbit must have no less than 4.1 million Solar Masses (8.2 × 10³³ metric tons; 9.04 × 10³³ US tons). Furthermore, the radius of this object would have to be less than 120 AU, otherwise S2 would collide with it.

However, the best evidence to date was provided in 2008 by the Max Planck Institute for Extraterrestrial Physics and UCLAs Galactic Center Group. Using data obtained over a 16 year period by the ESO’s Very Large Telescope and Keck Telescope, they were able to not only accurately estimate the distance to the center of our galaxy (27,000 light years from Earth), but also track the orbits of the stars there with immense precision.

As Reinhard Genzel, the team leader from the Max-Planck-Institute for Extraterrestrial Physics said:

“Undoubtedly the most spectacular aspect of our long term study is that it has delivered what is now considered to be the best empirical evidence that supermassive black holes do really exist. The stellar orbits in the Galactic Centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt.”

Another indication of Sagittarius A*s presence came on January 5th, 2015, when NASA reported a record-breaking X-ray flare coming from the center of our galaxy. Based on readings from the Chandra X-ray Observatory, they reported emissions that were 400 times brighter than usual. These were thought to be the result of an asteroid falling into the black hole, or by the entanglement of magnetic field lines within the gas flowing into it.

Other Galaxies:

Astronomers have also found evidence of SMBHs at the center of other galaxies within the Local Group and beyond. These include the nearby Andromeda Galaxy (M31) and elliptical galaxy M32, and the distant spiral galaxy NGC 4395. This is based on the fact that stars and gas clouds near the center of these galaxies show an observable increase in velocity.

Another indication is Active Galactic Nuclei (AGN), where massive bursts of radio, microwave, infrared, optical, ultra-violet (UV), X-ray and gamma ray wavebands are periodically detected coming from the regions of cold matter (gas and dust) at the center of larger galaxies. While the radiation is not coming from the black holes themselves, the influence such a massive object would have on surrounding matter is believed to be the cause.

In short, gas and dust form accretion disks at the center of galaxies that orbit supermassive black holes, gradually feeding them matter. The incredible force of gravity in this region compresses the disk’s material until it reaches millions of degrees kelvin, generating bright radiation and electromagnetic energy. A corona of hot material forms above the accretion disc as well, and can scatter photons up to X-ray energies.

The interaction between the SMBH rotating magnetic field and the accretion disk also creates powerful magnetic jets that fire material above and below the black hole at relativistic speeds (i.e. at a significant fraction of the speed of light). These jets can extend for hundreds of thousands of light-years, and are a second potential source of observed radiation.

When the Andromeda Galaxy merges with our own in a few billion years, the supermassive black hole that is at its center will merge with our own, producing a much more massive and powerful one. This interaction is likely to kick several stars out of our combined galaxy (producing rogue stars), and is also likely to cause our galactic nucleus (which is currently inactive) to become active one again.

The study of black holes is still in its infancy. And what we have learned over the past few decades alone has been both exciting and awe-inspiring. Whether they are lower-mass or supermassive, black holes are an integral part of our Universe and play an active role in its evolution.

Who knows what we will find as we peer deeper into the Universe? Perhaps some day we the technology, and sheer audacity, will exist so that we might attempt to peak beneath the veil of an event horizon. Can you imagine that happening?

We have written many interesting articles about black holes here at Universe Today. Here’s Beyond Any Reasonable Doubt: A Supermassive Black Hole Lives in Centre of Our Galaxy, X-Ray Flare Echo Reveals Supermassive Black Hole Torus, How Do You Weigh a Supermassive Black Hole? Take its Temperature, and What Happens When Supermassive Black Holes Collide?

Astronomy Cast also some relevant episodes on the subject. Here’s Episode 18: Black Holes Big and Small, and Episode 98: Quasars.

More to explore: Astronomy Cast’s episodes Quasars, and Black Holes Big and Small.

Sources:

Posted on by Tammy Plotner

Messier 28 – The NGC 6626 Globular Cluster

Messier 28, Messier 22 and Kaus Borealis. Credit: Wikisky

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Globular Cluster known as Messier 28. Enjoy!

Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of them so that others would not make the same mistake he did. In time, this list would come to include 100 of the most fabulous objects in the night sky.

One of these objects was the globular cluster now known as Messier 28. Located in the direction of the Sagittarius constellation, some 17,900 light-years from Earth, this “nebulous” cluster is easily detectable in the night sky. It is also the third largest known clustering of millisecond pulsars in the known Universe.

Description:

Compressed into a sphere measuring about 60 light years in diameter, globular star cluster Messier 28 happily orbits our galactic center about 19,000 light years away from Earth. In all of its thousands upon thousands of stars, M28 contains 18 known RR Lyrae variables and a W Virginis variable star. This very different variable is a Type II, or population II Cepheid that has a precise change rate which occurs every 17 days.

Image based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).
Image of Messier 28, based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive. Credit: STScI/NASA/ST-EFC/ESA/CADC/NRC/CSA

There has also been a second long period variable discovered, which could very well be an RV Tauri type, too. However, one of M28’s biggest claims to fame happened in 1986, when it became the first globular cluster known to contain a millisecond pulsar. This was discovered by the Lovell Telescope at Jodrell Bank Observatory. The work on the pulsar was later picked up by Chandra researchers.

As Martin C. Weisskopf (et al) of the Space Sciences Department put it in a 2002 study of the object:

“We report here the results of the first Chandra X-Ray Observatory observations of the globular cluster M28 (NGC 6626). We detect 46 X-ray sources of which 12 lie within one core radius of the center. We measure the radial distribution of the X-ray sources and fit it to a King profile finding a core radius. We measure for the first time the unconfused phase-averaged X-ray spectrum of the 3.05-ms pulsar B1821–24 and find it is best described by a power law with photon index. We find marginal evidence of an emission line centered at 3.3 keV in the pulsar spectrum, which could be interpreted as cyclotron emission from a corona above the pulsar’s polar cap if the magnetic field is strongly different from a centered dipole. We present a spectral analyses of the brightest unidentified source and suggest that it is a transiently accreting neutron star in a low-mass X-ray binary, in quiescence. In addition to the resolved sources, we detect fainter, unresolved X-ray emission from the central core.”

And the search has far from ended as even more X-ray counterparts have been discovered inside this seemingly quiet globular cluster! As W. Becker and C.Y. Hui of the Max Planck Institute wrote in their 2007 study:

“A recent radio survey of globular clusters has increased the number of millisecond pulsars drastically. M28 is now the globular cluster with the third largest population of known pulsars, after Terzan 5 and 47 Tuc. This prompted us to revisit the archival Chandra data on M28 to evaluate whether the newly discovered millisecond pulsars find a counterpart among the various X-ray sources detected in M28 previously. The radio position of PSR J1824-2452H is found to be in agreement with the position of CXC 182431-245217 while some faint unresolved X-ray emission near to the center of M28 is found to be coincident with the millisecond pulsars PSR J1824-2452G, J1824-2452J, J1824-2452I and J1824-2452E.”

Messier 28. Credit: NASA/ESA/HST
The globular cluster Messier 28, image by the Hubble Space Telescope. Credit: NASA/ESA/HST

So is it possible that these can be seen? According to the 2001 study – “A search for the optical counterpart to PSR B1821-24 in M 28” – by Hubble researcher A Golden (et al.):

“We have analyzed archival HST/WFPC2 images in both the F555W & F814W bands of the core field of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of V $\sim$ 24.5 (V0 $\sim$ 23.0). Each were further investigated, both in the context of the CMD of M 28, and also with regard to phenomenological models of pulsar magnetospheric emission. The latter was based on both luminosity-spindown correlations and known spectral flux density behaviour in this regime from the small population of optical pulsars observed to date. None of the potential candidates exhibited emission expected from a magnetospherically active pulsar. The fact that the magnetic field & spin coupling for PSR B1821-24 is of a similar magnitude to that of the Crab pulsar in the vicinity of the light cylinder has suggested that the millisecond pulsar may well be an efficient nonthermal emitter. ASCA’s detection of a strong synchrotron-dominated X-ray pulse fraction encourages such a viewpoint. We argue that only future dedicated 2-d high speed photometry observations of the radio error-circle can finally resolve this matter.”

History of Observation:

This globular cluster was an original discovery in July 1764 of Charles Messier who wrote in his notes:

“In the night of the 26th to the 27th of the same month, I have discovered a nebula in the upper part of the bow of Sagittarius, at about 1 degree from the star Lambda of that constellation, and little distant from the beautiful nebula which is between the head and the bow: that new one may be the third of the older one, and doesn’t contain any star, as far as I have been able to judge when examining it with a good Gregorian telescope which magnifies 104 times: it is round, its diameter is about 2 minutes of arc; one sees it with difficulty with an ordinary refractor of 3 feet and a half of length. I have compared the middle with the star Lambda Sagittarii, and I have concluded its right ascension of 272d 29′ 30″, and its declination of 37d 11′ 57″ south.”

As always, Sir William Herschel would often revisit with Messier’s objects for his own private observations and in his notes he states:

“It may be called insulated though situated in a part of the heavens that is very rich in stars. It may have a nucleus, for it is much compressed towards the centre, and the situation is too low for seeing it well. The stars of the cluster are pretty numerous.” It would be his son, John Herschel who would give M28 its New General Catalog Number and describe it as “Not very bright; but very rich, excessively compressed globular cluster; stars of 14th to 15th magnitude; much brighter toward the middle; a fine object.”

The location of Messier 28, in the direction of the Sagittarius Constellation. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)
The location of Messier 28, in the direction of the Sagittarius Constellation. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)

Regardless of whether or not you use binoculars or a telescope on M28, part of the joy of this object is understand how very rich the stellar field is in which it appears. As John Herschel once said of M28 in his many observations, “Occurs in the milky way, of which the stars here are barely visible and immensely numerous.”

Locating Messier 28:

Finding M28 is another easy object once you’ve familiarized yourself with the “teapot” asterism of the constellation of Sagittarius. In binoculars, simply center Lambda in the field of view and you will see Messier 28 as a small, faded grey circular area in the 1:00 position away from the marker star.

In the finderscope of telescope, you can start by centering on Lambda and go to the eyepiece and simply shift the telescope to the northwest slowly and Messier 28 will pop into view. While this globular cluster is easily bright enough to be seen in the smallest of optics, it will require at least a 4″ telescope before it begins any resolution of individual stars and telescopes in the 10″ and larger range will fully appreciate all it has to offer.

And here are the quick facts to help you get started:

Object Name: Messier 28
Alternative Designations: M28, NGC 6626
Object Type: Class IV Globular Cluster
Constellation: Sagittarius
Right Ascension: 18 : 24.5 (h:m)
Declination: -24 : 52 (deg:m)
Distance: 18.3 (kly)
Visual Brightness: 6.8 (mag)
Apparent Dimension: 11.2 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

Posted on by Matt Williams

NASA Technology Used To Find Stone Age Structures

The Phoenix Mars Lander used a lidar device built by Teledyne Optech to detect snow in the Martian atmosphere in 2008. Credits: NASA

Oklahoma’s Beaver River is an incredibly historic place. Anthropologists estimate that as early as 10,500 years ago, human beings hunted bison in the region. Being without horses, the hunter-gatherers would funnel herds into narrow, dead-end gullies cut into the hillside by the river. Once there, they would kill them en masse, taking the meat and organs and leaving the skeletons behind.

Sadly, no visible trace of this history remains in the region today, thanks to weathering and erosion. But according to a recent story released by NASA, the same technology that powers the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission has made the ancient history of this region visible for all to see.

Having launched back in September of 2016, the robotic spacecraft OSIRIS-REx is scheduled to rendezvous with the Near-Earth Asteroid Bennu in 2023. The purpose of the mission is to obtain samples of the carbonaceous object and return them to Earth, thus helping scientists to get a better understanding of the formation and evolution of the Solar System, as well as the source of organic compounds that led to the formation of life on Earth.


Once it reaches Bennu, it will rely on light-detection and ranging (aka. lidar) to map the asteroid and help the mission team select a landing site. This technology uses one or more lasers to send out short pulses that bounce off of nearby objects. The instrument then measures how long it takes for the signal to return to get an accurate assessment of distance and generate topographical information.

The OSIRIS-REx Laser Altimeter (OLA) instrument was designed by Teledyne Optech, a company that has worked with NASA many times in the past. Their work includes the laser instrument that was used by the Phoenix Lander to detect snow in the Martian atmosphere back in 2008. And more recently, it was used by an archeological research team in the Beaver River area to create a detailed picture of its past.

Using an airborne version of the Teledyne Optech lidar device, the team was able to create a 3-D model of the surface. They were also able to generate as a ‘bare-earth” version of the area that showed what the land looked like without all of the concealing features – i.e. rocks, trees and grass – that hide its past.

In so doing, they were able to figure out where they should dig to find evidence that the region was once a major hunting ground. As Paul LaRoque, vice president of special projects at Teledyne Optech, explained, this process allowed the archaeologists to “see structures or features that were so overgrown that they wouldn’t be obvious at all to someone on the ground.”

Aerial photograph of a forest in Connecticut (left), and bare-earth lidar image beneath the overgrown vegetation (right) showing the remnants of stone walls, building foundations, abandoned roads and what was once cleared farm land. Credits: NASA/Katharine Johnson
Aerial photograph of a forest in Connecticut (left), and bare-earth lidar image beneath the vegetation (right) showing archaeological remains. Credits: UofConn/Katharine Johnson

This sort of process has also been used by other archaeological teams to make major finds, like uncovering the lost “Ciudad Blanca” (aka. the “City of the Monkey God”) of Honduras. This ancient Mesoamerican settlement, which is believed to have been built between the 1st and 2nd millennium CE, had remained the stuff of legend for centuries. Despite multiple claims by explorers, no confirmed discovery was ever made.

But thanks to a joint effort by archaeologists from the University of Florida and  the Houston-based National Center for Airborne Laser Mapping, an archaeological team was able to create images that stripped away the lush rainforest to revealed multiple structures – including pyramids, a plaza, a possible ball court, and many houses.

Lidar was also used by a research team from the University of Connecticut for the sake of studying the dynamics between human settlement and the historic landscape of New England. Using publicly available data, they were able to peer beneath all the current vegetation to detect the remnants of stone walls, building foundations, abandoned roads and what was once cleared farm land.

The revealing look at Beaver River is one of 50 stories that will be released on Dec. 5th, as part of a NASA Spinoff publication. Each year, Spinoff profiles about 50 NASA technologies that have transformed into commercial products and services, demonstrating the wider benefits of America’s investment in its space program. Spinoff is a publication of the Technology Transfer Program in NASA’s Space Technology Mission Directorate.

Further Reading: NASA

Posted on by Matt Williams

227 Stars Given Names By International Astronomical Union

The Sagittarius constellation, as imaged by the Hubble Space Telescope. Credit: IAU/NASA/ESA/HST

In May of 2016, the IAU Executive Committee approved of the creation of a special task force known as the Working Group on Star Names (WGSN). Composed of an international group of experts in astronomy, astronomical history, and cultural astronomy, the purpose of the WGSN is to formalize the names of stars that have been used colloquially for centuries.

This has involved sorting through the texts and traditions of many of the world’s cultures, seeking out unique names and standardizing their spelling. And after about six months, their labors have led to the creation of a new catalog of IAU star names, the first 227 of which were recently published on the IAU website.

This initiative grew out of the IAU’s Division C – Education, Outreach and Heritage group, which is responsible for engaging the public in all matters of astronomy. Their overall purpose is to establish IAU guidelines for the proposal and adoption of star names, to search historical and cultural literature for them, to adopt unique names that have scientific and historical value, and to publish and disseminate official IAU star name catalogs.

In this respect, the WGSN is breaking with standard astronomical practice. For many years, astronomers have named the stars they have been responsible for studying using an alphanumerical designation. These designations are seen as immensely practical, since star catalogs typically contain thousands, millions or even billions of objects. If there’s one thing the observable Universe has no shortage of, its stars!

However, many of these stars already have traditional names which may have fallen into disuse. The WGSN’s job, therefore, is to find commonly-used, traditional names of stars and determine which ones shall be officially used. In addition to preserving humanity’s astronomical heritage, this process is also intended to make sure that there is standardization in terms of naming and spelling, so as to prevent confusion.

What’s more, with the discovery of exoplanets becoming a regular thing nowadays, the IAU hopes to engage the international astronomical community in naming these planets according to their stars traditional name (if they have one). As Eric Mamajek, the chair and organiser of the WGSN, explained their purpose:

“Since the IAU is already adopting names for exoplanets and their host stars, it has been seen as necessary to catalogue the names for stars in common use from the past, and to clarify which ones will be official from now on.”

Artist's impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL
Artist’s impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL

For instance, it can certainly be said that HD 40307 g – an exoplanet candidate that orbits within the habitable zone of its K-type star some 42 light years away – has a pretty clunky name. But what if, upon searching through various historical sources, the WGSN found that this star was traditionally known as “mikiya” (eagle) to the Hausa people of northern Nigeria? Then this super-Earth could be named Mikiya g (or Mikiya Prime). Doesn’t that sound cooler?

And this effort is hardly without precedent. As Mamajek explained, the IAU engaged in a very similar effort decades ago with respect to the constellations:

“A similar effort was conducted early in the history of the IAU, in the 1920s, when the 88 modern constellations were clarified from historical literature, and their boundaries, names, spellings, and abbreviations were delineated for common use in the international astronomical community. Many of these names are used today by astronomers for designations of variable stars, names for new dwarf galaxies and bright X-ray sources, and other astronomical objects.”

Much like the constellations, the new star names are largely rooted in astronomical and cultural traditions of the Ancient Near East and Greece. Their names are rendered in Greek, Latin or Aabic, and have likely undergone little change since the Renaissance, a time where the production of star catalogs, atlases and globes experienced an explosion in growth.

Illustration of the red supergiant Betelgeuse, as seen from a fictional orbiting world. © Digital Drew.
Illustration of the red supergiant Betelgeuse, a traditionally-named star, as seen from a fictional orbiting world. © Digital Drew.

Others, however, are more recent in origin, having been discovered and named in the  19th or 20th centuries. The IAU is looking to locate as many ancient names as possible, then incorporate them into an official IAU-approved database with more modern stars. These databases will be made available for use by astronomers, navigators and the general public.

In accordance with WGSN guildines, shorter, one-word names are preferred, as are those that have their roots in astronomical, cultural or natural world heritage. The 227 names that have been released include 209 recently approved names by the WGSN, plus the 18 stars that the IAU Executive Committee Working Group for Public Naming of Planets and Planetary Satellites approved of in December 2015.

Among those names that were approved are Proxima Centauri (which is orbited by the closest exoplanet to Earth, Proxima b), as well as Rigil Kentaurus (the ancient name for Alpha Centauri), Algieba (Gamma-1 Leonis), Hamal (Alpha Arietis), and Muscida (Omicron Ursae Majoris).

This number is expected to grow, as the WGSN continues to revive ancient stellar names and add new ones that are suggested by the international astronomical community.

Further Reading: IAU

Posted on by Matt Williams

What is Cydonia?

Image of the "Face of Mars" by the Mars Reconnaissance Orbiter, with the Viking 1 image inset (bottom right). Credit: NASA/JPL
Image of the "Face of Mars" by the Mars Reconnaissance Orbiter, with the Viking 1 image inset (bottom right). Credit: NASA/JPL

The surface of Mars has been the subject of fascination for centuries. Even sinceGiovanni Schiaparelli first announced that he had observed the “Martian Canals” in 1877, the Red Planet has been a source of endless speculation. Even today, crystal-clear images sent directly from the surface by rovers are still the subject of pareidolia – where people see familiar patterns in random features.

Nowhere has this tendency of seeing what we want to see on the surface of Mars been made more clean than with the Cydonia region. Located in the northern hemisphere, this region of Mars is known for its many interesting land forms. The most famous of these is the “Face of Mars”, which has attracted immense scientific and popular curiosity over the past few decades.

Location:

The area called Cydonia is in the northern hemisphere of Mars, in between the heavily cratered regions of the south (the Arabia Terra highlands) and the smooth plains to the north (Acidalia Planitia). The area includes the regions of flat-topped mesa-like featured (“Cydonia Mensae”), a region of small hills or knobs, (“Cydonia Colles”) and a complex of intersecting valleys (“Cydonia Labyrinthus”).

Cydonia Region under infrared light. Credit: NASA/JPL
Image of the Cydonia region under infrared light taken by the Viking 1 orbiter. Credit: NASA/JPL

Because of its geographical location, it is possible that Cydonia was once a coastal plain region, billions of years ago when the northern hemisphere of Mars is believed to have been covered with water. The name – like many featured on Mars – is drawn from classical antiquity; in this case, from the historic city-state of Kydonia, which was located on the island of Crete.

Exploration:

Cydonia was first photographed by the Viking 1 and 2 orbiters. Between the two, eighteen images were taken of the region, all of which were of limited resolution. Of these, only five were considered suitable for studying surface features. Because of their limited quality, a particular mesa resembled a humanoid face (see below).

It would be another 20 years before other spacecraft photographed the region as they conducted observations of Mars. These included NASA’s Mars Global Surveyor, which orbited Mars from 1997 to 2006; the Mars Reconnaissance Orbiter (MRO), which reached the planet in 2006 and is still in operation; and the ESA’s Mars Express probe – which has been in orbit since 2003.

Each of these missions provided images of Cydonia which were much better in terms of resolution and debunked the existence of an artificial “Face of Mars” feature. After analyzing images taken by the Mars Global Surveyor, NASA declared that “a detailed analysis of multiple images of this feature reveals a natural looking Martian hill whose illusory face-like appearance depends on the viewing angle and angle of illumination”.

A section of the Cydonia region, taken by the Viking 1 orbiter and released by NASA/JPL on July 25, 1976. Credit: NASA/JPL
A section of the Cydonia region, taken by the Viking 1 orbiter and released on July 25, 1976. Credit: NASA/JPL

Notable Features:

As already noted, Cydonia’s best known feature is the famous “Face of Mars“. This 2 km long mesa, which was first photographed by the Viking 1 orbiter on July 25th, 1976, initially was thought to resemble a human face. At the time, the NASA science team dismissed this as a “trick of light and shadow”. But a second image, acquired 35 orbits later at a different angle, confirmed the existence of the “Face of Mars”.

Vincent DiPietro and Gregory Molenaar, two computer engineers at NASA’s Goddard Space Flight Center, independently discovered this image while searching through the NASA archives. From 1982 onward, these images would lead  widespread speculation about what could have caused it, and fueled interest in the possible existence of a civilization on Mars.

In addition, DiPeitro and Molenaar noticed several mountains near the “Face” that had angular peaks, which they referred to as “pyramids“. One in particular, a 500 meter-tall mountain located to the south-west, was especially geometric in shape. Richard Hoagland, a famous conspiracy theorist, dubbed it the “D&M Pyramid” (in honor of DiPietro and Molenaar), a name which stuck.

Last, but not least, there is also the area to the north of the “Face” that was dubbed “the city”, because of its supposed resemblance to a series of monuments. These consisted predominately of more ‘pyramids’ that are arranged in a circular pattern around a series of smaller rocky features, known as the “City Square” (see below).

Mosaic created from images taken by the Viking orbiter, showing landforms in Cydonia with popular, informal names. Credit: NASA/JPL
Mosaic created from images taken by the Viking orbiter, showing landforms in Cydonia with popular, informal names. Credit: NASA/JPL

Later images provided by the Mars Global Surveyor, the MRO and the Mars Express all resolved these features with far greater accuracy, showing them to be natural features with no evidence of construction of manipulation. In all cases, psychologists indicated that the desire to see familiar shapes and patterns was an example of pareidolia.

And this was hardly the last time that this phenomena has happened with Martian features! In fact, the human race has a long history of seeing patterns within our Solar System and the cosmos in general. Consider the “Man in the Moon”, the Butterfly Nebula, and the “Mickey Mouse” on Mercury.

As for the Cydonia region, future missions to the planet may take an interest in exploring it further. However, this will most likely to get a better understanding of the regions past and see it was indeed a coastal region at one time. There will be NO attempts to search for signs of ziggurats, pyramids, ancient sarcophagi, or any other indications of a lost civilization.

We have written many articles about the Cydonia and other features on the surface of Mars. Here’s Extreme Close-Up of the Face of Mars, Pyramids on Mars, Detailed Deconstruction of the “Face” and Pyramids on Mars Claims, Faces and Animals on Mars? Pure Pareidolia!, Faces of the Solar System, No Humanoid on Mars, Just Rocks, and No, a Dinosaur Skull Hasn’t Been Found on Mars: Why We See Familiar Looking Objects on the Red Planet.

If you’d like more info on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We’ve also recorded several episodes of Astronomy Cast all about Mars. Start here, Episode 52: Mars.

Sources:

Posted on by Fraser Cain

Weekly Space Hangout – November 25, 2016: Dean Regas and his “Facts from Space”

Host: Fraser Cain (@fcain)

Special Guest:
Dean Regas has been the Astronomer for the Cincinnati Observatory since 2000. He is the co-host of Star Gazers (airing on PBS stations around the world), a Contributing Editor to Sky and Telescope Magazine, and a contributor to Astronomy Magazine. Dean is the author of the new book, “Facts from Space! From Super-Secret Spacecraft to Volcanoes in Outer Space, Extraterrestrial Facts to Blow Your Mind!”

Guests:

Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Yoav Landsman (@MasaCritit)

Their stories this week:
Cause of Schiaparelli’s crash: 1 second glitch

Let me tell you what I think of the EM Drive

We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!

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!

If you would like to sign up for the AstronomyCast Solar Eclipse Escape, where you can meet Fraser and Pamela, plus WSH Crew and other fans, visit our site linked above and sign up!

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page<