Artist's impression of a Near-Earth Asteroid passing by Earth. Credit: ESA
Within Earth’s orbit, there are literally thousands of what are known as Near-Earth Objects (NEOs), more than fourteen thousands of which are asteroids that periodically pass close to Earth. Since the 1980s, these objects have become a growing source of interest to astronomers, due to the threat they sometimes represent. But as ongoing studies and decades of tracking the larger asteroids has shown, they usually just pass Earth by.
More importantly, it is only on very rare occasions (i.e. over the course of millions of years) that a larger asteroid will come close to colliding with Earth. For example, this September 1st, the Near-Earth Asteroid (NEA) known as 3122 Florence, will pass by Earth, but poses no danger of hitting us. Good thing too, since this Near-Earth Asteroid is one of the largest yet to be discovered, measuring about 4.4 km (2.7 mi) in diameter!
To put that in perspective, the asteroid which is thought to have killed the dinosaurs roughly 65 million years ago (aka. the Cretaceous–Paleogene extinction event) is believed to have measured 10 km (6 mi) in diameter. This impact also destroyed three-quarters of the plant and animal species on Earth, hence why organizations like NASA’s Center for Near-Earth Object Studies (CNEOS) is in he habit of tracking the larger NEAs.
Asteroid Florence, a large near-Earth asteroid, will pass safely by Earth on Sept. 1, 2017, at a distance of about 7 million km (4.4 million mi). Credits: NASA/JPL-Caltech
Once again, NASA has determined that this particular asteroid will sail harmlessly by, passing Earth at a minimum distance of over 7 million km (4.4 million mi), or about 18 times the distance between the Earth and the Moon. As Paul Chodas – NASA’s manager of CNEOS at the Jet Propulsion Laboratory in Pasadena, California – said in a NASA press statement:
“While many known asteroids have passed by closer to Earth than Florence will on September 1, all of those were estimated to be smaller. Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began.”
Rather than being a threat, the flyby of this asteroid will be an opportunity for scientists to study it up close. NASA is planning on conducting radar studies of Florence using the Goldstone Solar System Radar in California, and the National Science Foundation’s (NSF) Arecibo Observatory in Peurto Rico. These studies are expected to yield more accurate data on its size, and reveal surface details at resolutions of up to 10 m (30 feet).
This asteroid was originally discovered on March 2nd, 1981, by American astronomer Schelte Bus at the Siding Spring Observatory in southwestern Australia. It was named in honor of Florence Nightingale (1820-1910) the founder of modern nursing. Measurements obtained by NASA’s Spitzer Space Telescope and the NEOWISE mission are what led to the current estimates on its size – about 4.4 km (2.7 mi) in diameter.
Artist’s rendition of how far Florence will pass by Earth. Credits: NASA/JPL-Caltech
The upcoming flyby will be the closest this asteroid has passed to Earth since August 31st, 1890, where it passed at a distance of 6.7 million km (4.16 million mi). Between now and then, it also flew by Earth on August 29th, 1930, passing Earth at a distance of about 7.8 million km (4.87 million mi). While it will pass Earth another seven times over the course of the next 500 years, it will not be as close as it will be this September until after 2500.
For those interesting into doing a little sky watching, Florence will be brightening substantially by late August and early September. During this time, it will be visible to those using small telescopes for several nights as it moves through the constellations of Piscis Austrinus, Capricornus, Aquarius and Delphinus.
Be sure to check out these animations of Florence’s orbit and its close flyby to Earth:
Artist's impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
In the past few years, there has been no shortages of extra-solar planets discoveries which orbit red dwarf stars. In 2016 and 2017 alone, astronomers announced the discovery of a terrestrial (i.e. rocky) planet around Proxima Centauri (Proxima b), a seven-planet system orbiting TRAPPIST-1, and super-Earths orbiting the nearby stars of LHS 1140 (LHS 1140b), and GJ 625 (GJ 625b).
In what could be the latest discovery, physicists at the University of Texas Arlington (UTA) recently announced the possible discovery of an Earth-like planet orbiting Gliese 832, a red dwarf star just 16 light years away. In the past, astronomers detected two exoplanets orbiting Gliese 832. But after conducting a series of computations, the UTA team indicated that an additional Earth-like planet could be orbiting the star.
The study which details their findings, titled “Dynamics of a Probable Earth-mass Planet in the GJ 832 System“, recently appeared in The Astrophysical Journal. Led by Dr. Suman Satyal – a physics researcher, lecturer and laboratory supervisor at UTA – the team sought to investigate the stability of planetary orbits around Gliese 832 using a numerical and detailed phase-space analysis.
Artistic representation of the potentially habitable exoplanet Gliese 832c as compared with Earth. Credit: PHL/UPR Arecibo.
As indicated, two other exoplanets had been discovered around Gliese 832 in the past, including a Jupiter-like gas giant (Gliese 832b) in 2008, and the super-Earth (Gliese 832c) in 2014. In many ways, these planets could not be more different. In addition to their disparity in mass, they vary widely in terms of their orbits – with Gliese 832b orbiting at a distance of about 0.16 AU and Gliese 832c orbiting at a distance of 3 to 3.8 AU.
Because of this, the UTA team sought to determine if perhaps there was a third planet with a stable orbit between the two. To this end, they conducted numerical simulations for a three and four body system of planets with elliptical orbits around the star. These simulations took into account a large number of initial conditions, which allowed for all possible states (aka. s phase-space simulation) of the planet’s orbits to be represented.
They then included the radial velocity measurements of Gliese 832, accounting for them based on the presence of planets with 1 to 15 Earth masses. The Radial Velocity (RV) method, it should be noted, determines the existence of planets around a star based on variations in the star’s velocity. In other words, the fact that a star is moving back and forth indicates that it is being influenced by the presence of a planetary system.
Simulating the star’s RV signal using a hypothetical system of planets also allowed the UTA team to constrain the average distances at which these planets would orbit the star (aka. their semi-major axes) and their upper mass-limits. In the end, their results provided strong indications for the existence of a third planet. As Dr. Satyal explained in a UTA press release:
“We also used the integrated data from the time evolution of orbital parameters to generate the synthetic radial velocity curves of the known and the Earth-like planets in the system. We obtained several radial velocity curves for varying masses and distances indicating a possible new middle planet.”
Diagram showing the possible orbit of a third exoplanet around Gliese 832, a star system located just 16 light years away. Credit: uta.edu/Suman Satyal
Based on their computations, this possible planet of the Gliese 832 system would be between 1 and 15 Earth masses and would orbit the star at a distance ranging from 0.25 to 2.0 AU. They also determined that it would likely have a stable orbit for about 1 billion years. As Dr. Satyal indicated, all signs coming from the Gliese 832 system point towards there being a third planet.
“The existence of this possible planet is supported by long-term orbital stability of the system, orbital dynamics and the synthetic radial velocity signal analysis,” he said. “At the same time, a significantly large number of radial velocity observations, transit method studies, as well as direct imaging are still needed to confirm the presence of possible new planets in the Gliese 832 system.”
Alexander Weiss, the UTA Physics Chair, also lauded the achievement, saying:
“This is an important breakthrough demonstrating the possible existence of a potential new planet orbiting a star close to our own. The fact that Dr. Satyal was able to demonstrate that the planet could maintain a stable orbit in the habitable zone of a red dwarf for more than 1 billion years is extremely impressive and demonstrates the world class capabilities of our department’s astrophysics group.”
Artist’s impression of a Super-Earth orbiting close to a red dwarf star. Credit: M. Weiss/CfA
Another interesting tidbit is that this planet’s orbit would place it beyond or just within Gliese 832’s habitable zone. Whereas the Super-Earth Gliese 832c has an eccentric orbit that places it at the inner edge of this zone, this third planet would skirt its outer edge at the nearest. In this sense, Gliese 832’s two Super-Earths could very well be Venus-like and Mars-like in nature.
Looking ahead, Dr. Satyal and his colleagues will be naturally be looking to confirm the existence of this planet, and other institutions are sure to conduct similar studies. This star system is yet another that is sure to be the subject of follow-up studies in the coming years, most likely from next-generation space telescopes like the James Webb Space Telescope.
The United Launch Alliance Atlas V rocket carrying NASA’s Tracking and Data Relay Satellite-M (TDRS-M) stands on the launch pad at Space Launch Complex 41 on Cape Canaveral Air Force Station poised for liftoff on Aug. 18, 2017 The rocket rolled out to the pad two days earlier on Aug. 16. Credit: Ken Kremer/kenkremer.com
The United Launch Alliance Atlas V rocket carrying NASA’s Tracking and Data Relay Satellite-M (TDRS-M) stands on the launch pad at Space Launch Complex 41 on Cape Canaveral Air Force Station poised for liftoff on Aug. 18, 2017. The rocket rolled out to the pad two days earlier on Aug. 16. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER, FL – The last of NASA’s next generation Tracking and Data Relay Satellites (TRDS) that looks like a giant alien fish or cocooned creature but actually plays an absolutely vital role in relaying critical science measurements, research data and tracking observations gathered by the International Space Station (ISS), Hubble and a plethora of Earth science missions is poised for blastoff Friday, Aug. 18, morning from the Florida Space Coast.
Liftoff atop a United Launch Alliance Atlas V rocket of NASA’s $408 million eerily insectoid-looking TDRS-M science relay comsat atop a United Launch Alliance (ULA) Atlas V rocket is scheduled to take place from Space Launch Complex 41 at Cape Canaveral Air Force Station at 8:03 a.m. EDT (2:03 GMT) Aug. 18.
Up close clean room visit with NASA’s newest science data relay comsat – Tracking and Data Relay Satellite-M (TDRS-M) inside the Astrotech payload processing facility high bay in Titusville, FL. Two gigantic fold out antennae’s, plus space to ground antenna dish visible inside the ‘cicada like cocoon’ with solar arrays below. Launch on ULA Atlas V slated for August 2017 from Cape Canaveral Air Force Station, Fl. Credit: Ken Kremer/kenkremer.com
The Atlas V/TDRS-M launch stack was rolled out from the ULA Vertical Integration Facility (VIF) to pad 41 Wednesday morning, Aug 16 starting at about 9:10 a.m. EDT. The quarter mile move took about 50 minutes and went off without a hitch.
“The spacecraft, Atlas V rocket and all range equipment are ready,” said NASA launch director Tim Dunn at today’s pre-launch news conference at the Kennedy Space Center. “And the combined government and contractor launch team is prepared to launch TDRS-M — a critical national space asset for space communications.”
The rocket and spacecraft sailed through the Flight Readiness Review (FRR) and Launch Ready Review (LRR) over the past few days conducted by NASA, ULA and Boeing and the contractor teams.
The two stage Atlas V rocket stands 191 feet tall.
The United Launch Alliance Atlas V rocket carrying NASA’s Tracking and Data Relay Satellite-M (TDRS-M) stands on the launch pad at Space Launch Complex 41 on Cape Canaveral Air Force Station poised for liftoff on Aug. 18, 2017. The rocket rolled out from the VIF the pad two days earlier on Aug. 16. Credit: Ken Kremer/kenkremer.com
You can witness the launch with you own eyes from many puiblic beaches, parks and spots ringing the Kennedy Space Center.
If you can’t personally be here to witness the launch in Florida, you can always watch NASA’s live coverage on NASA Television and the agency’s website.
The NASA/ULA/TDRS-M launch coverage will be broadcast on NASA TV beginning at 7:30 a.m. as the countdown milestones occur on Aug. 18 with additional commentary on the NASA launch blog:
The launch window opens at 8:03 a.m. EDT extends for 40 minutes from 8:03 a.m. to 8:43 a.m.
In the event of delay for any reason, the next launch opportunity is Saturday, Aug. 19 with NASA TV coverage starting about 7:30 a.m. EDT. The launch window opens at 7:59 a.m. EDT.
The United Launch Alliance Atlas V rocket carrying NASA’s Tracking and Data Relay Satellite-M (TDRS-M) stands on the launch pad at Space Launch Complex 41 on Cape Canaveral Air Force Station poised for liftoff on Aug. 18, 2017 The rocket rolled out to the pad two days earlier on Aug. 16. Credit: Ken Kremer/kenkremer.com
The weather looks quite good at this time with an 80% chance of favorable conditions at launch time according to U.S. Air Force meteorologists with the 45th Space Wing Weather Squadron at Patrick Air Force Base. The primary concerns on Aug. 18 are for thick clouds and cumulus clouds.
The odds remain at 80% favorable for the 24 hour scrub turnaround day on Aug. 19.
The launch was originally scheduled for Aug. 3 but was delayed a few weeks when the satellite’s Omni S-band antenna was damaged during final spacecraft closeout activities.
The Omni S-band antenna was bumped during final processing activities prior to the planned encapsulation inside the nosecone, said a Boeing official at the prelaunch media briefing and had to be replaced and then retested. It is critical to the opening phases of the mission for attitude control.
Inside the Astrotech payload processing facility in Titusville, FL,NASA’s massive, insect like Tracking and Data Relay Satellite, or TDRS-M, spacecraft is undergoing preflight processing during media visit on 13 July 2017. TDRS-M will transmit critical science data gathered by the ISS, Hubble and numerous NASA Earth science missions. It is being prepared for encapsulation inside its payload fairing prior to being transported to Launch Complex 41 at Cape Canaveral Air Force Station for launch on a United Launch Alliance (ULA) Atlas V rocket on 3 August 2017. Credit: Ken Kremer/kenkremer.com
The importance of the TDRS constellation of satellites can’t be overstated.
Virtually all the communications relay capability involving human spaceflight, such as the ISS, resupply vehicles like the SpaceX cargo Dragon and Orbital ATK Cygnus and the soon to launch human space taxis like crew Dragon, Boeing Starliner and NASA’s Orion deep space crew capsule route their science results voice, data, command, telemetry and communications via the TDRS network of satellites.
The TDRS constellation enables both space to space and space to ground communcations for virtually the entire orbital period.
Plus it’s a super busy time at the Kennedy Space Center. Because, if all goes well Friday’s launch will be the second this week!
The excitement of space travel got a big boost at the beginning of the week with the lunchtime blastoff of a SpaceX Falcon 9 and Dragon spacecraft on a cargo mission carrying 3 tons of science and supplies to the space station. Read my onsite articles here.
Blastoff of SpaceX Dragon CRS12 on its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017 as seen from the VAB roof. Credit: Ken Kremer/Kenkremer.com
The success of Monday’s SpaceX cargo Dragon rendezvous and berthing to the ISS is virtually entirely dependent on the TDRS network of satellites. That network will be enhanced with Fridays planned liftoff of NASA’s TDRS-M science relay comsat.
TDRS-M looks like a giant insect – or a fish depending on your point of view. It was folded into flight configuration for encapsulation in the clean room and the huge pair of single access antennas resembled a cocoon or a cicada. The 15 foot diameter single access antennas are large parabolic-style antennas and are mechanically steerable.
What does TDRS do? Why is it important? How does it operate?
“The existing Space Network of satellites like TDRS provide constant communications from other NASA satellites like the ISS or Earth observing satellites like Aura, Aqua, Landsat that have high bandwidth data that needs to be transmitted to the ground,” TDRS Deputy Project Manager Robert Buchanan explained to Universe Today during an interview in the Astrotech clean room.
“TRDS tracks those satellites using antennas that articulate. Those user satellites send the data to TDRS, like TDRS-M we see here and nine other TDRS satellites on orbit now tracking those satellites.”
“That data acquired is then transmitted to a ground station complex at White Sands, New Mexico. Then the data is sent to wherever those user satellites want the data to be sent is needed, such as a science data ops center or analysis center.”
The United Launch Alliance Atlas V rocket carrying NASA’s Tracking and Data Relay Satellite-M (TDRS-M) stands on the launch pad at Space Launch Complex 41 on Cape Canaveral Air Force Station poised for liftoff on Aug. 18, 2017. The rocket rolled out to the pad two days earlier on Aug. 16. Credit: Ken Kremer/kenkremer.com
TDRS-M, spacecraft, which stands for Tracking and Data Relay Satellite – M is NASA’s new and advanced science data relay communications satellite that will transmit research measurements and analysis gathered by the astronaut crews and instruments flying abroad the International Space Station (ISS), Hubble Space Telescope and over 35 NASA Earth science missions including MMS, GPM, Aura, Aqua, Landsat, Jason 2 and 3 and more.
The TDRS constellation orbits 22,300 miles above Earth and provide near-constant communication links between the ground and the orbiting satellites.
Tracking and Data Relay Satellite artwork explains how the TDRS constellation enables continuous, global communications coverage for near-Earth spacecraft. Credit: NASA
TRDS-M will have S-, Ku- and Ka-band capabilities. Ka has the capability to transmit as much as six-gigabytes of data per minute. That’s the equivalent of downloading almost 14,000 songs per minute says NASA.
The TDRS program is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
TDRS-M is the third satellite in the third series of NASA’s American’s most powerful and most advanced Tracking and Data Relay Satellites. It is designed to last for a 15 year orbital lifetime.
The first TDRS satellite was deployed from the Space Shuttle Challenger in 1983 as TDRS-A.
TDRS-M was built by prime contractor Boeing in El Segundo, California and is the third of a three satellite series – comprising TDRS -K, L, and M. They are based on the Boeing 601 series satellite bus and will be keep the TDRS satellite system operational through the 2020s.
TDRS-K and TDRS-L were launched in 2013 and 2014.
The Tracking and Data Relay Satellite project is managed at NASA’s Goddard Space Flight Center.
TDRS-M was built as a follow on and replacement satellite necessary to maintain and expand NASA’s Space Network, according to a NASA description.
The gigantic satellite is about as long as two school buses and measures 21 meters in length by 13.1 meters wide.
It has a dry mass of 1800 kg (4000 lbs) and a fueled mass of 3,454 kilogram (7,615 lb) at launch.
TDRS-M will blastoff on a ULA Atlas V in the baseline 401 configuration, with no augmentation of solid rocket boosters on the first stage. The payload fairing is 4 meters (13.1 feet) in diameter and the upper stage is powered by a single-engine Centaur.
TDRS-M will be launched to a Geostationary orbit some 22,300 miles (35,800 km) above Earth.
“The final orbital location for TDRS-M has not yet been determined,” Buchanen told me.
The Atlas V booster was assembled inside the Vertical Integration Facility (VIF) at SLC-41 and was rolled out to the launch pad 2 days before liftoff with the TDRS-M science relay comsat comfortably encapsulated inside the nose cone.
Carefully secured inside its shipping container, the TDRS-M satellite was transported on June 23 by a US Air Force cargo aircraft from Boeing’s El Segundo, California facility to Space Coast Regional Airport in Titusville, Florida, for preflight processing at Astrotech.
Watch for Ken’s continuing onsite TDRS-M, CRS-12, ORS 5 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.
Learn more about the upcoming ULA Atlas TDRS-M NASA comsat on Aug. 18, 2017 , SpaceX Dragon CRS-12 resupply launch to ISS on Aug. 14, Solar Eclipse, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
Aug 17-18: “TDRS-M NASA comsat, SpaceX CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
The cloud-enshrouded Venus appears featureless, as shown in this image taken by NASA’s MESSENGER mission. In ultraviolet, however, the planet takes on a completely different appearance as seen below. Credits: NASA
From space, Venus looks like a big, opaque ball. Thanks to its extremely dense atmosphere, which is primarily composed of carbon dioxide and nitrogen, it is impossible to view the surface using conventional methods. As a result, little was learned about its surface until the 20th century, thanks to development of radar, spectroscopic and ultraviolet survey techniques.
Interestingly enough, when viewed in the ultraviolet band, Venus looks like a striped ball, with dark and light areas mingling next to one another. For decades, scientists have theorized that this is due to the presence of some kind of material in Venus’ cloud tops that absorbs light in the ultraviolet wavelength. In the coming years, NASA plans to send a CubeSat mission to Venus in the hopes of solving this enduring mystery.
The mission, known as the CubeSat UV Experiment (CUVE), recently received funding from the Planetary Science Deep Space SmallSat Studies (PSDS3) program, which is headquartered as NASA’s Goddard Space Flight Center. Once deployed, CUVE will determine the composition, chemistry, dynamics, and radiative transfer of Venus’ atmosphere using ultraviolet-sensitive instruments and a new carbon-nanotube light-gathering mirror.
Ultraviolet image of Venus taken by NASA’s Pioneer-Venus Orbiter in 1979, lending Venus a striped, light and dark appearance. Credit: NASA
The mission is being led by Valeria Cottini, a researcher from the University of Maryland who is also CUVE’s Principle Investigator (PI). In March of this year, NASA’s PSDS3 program selected it as one of 10 other studies designed to develop mission concepts using small satellites to investigate Venus, Earth’s moon, asteroids, Mars and the outer planets.
Venus is of particular interest to scientists, given the difficulties of exploring its thick and hazardous atmosphere. Despite the of NASA and other space agencies, what is causing the absorption of ultra-violet radiation in the planet’s cloud tops remains a mystery. In the past, observations have shown that half the solar energy the planet receives is absorbed in the ultraviolet band by the upper layer of its atmosphere – the level where sulfuric-acid clouds exist.
Other wavelengths are scattered or reflected into space, which is what gives the planet its yellowish, featureless appearance. Many theories have been advanced to explain the absorption of UV light, which include the possibility that an absorber is being transported from deeper in Venus’ atmosphere by convective processes. Once it reaches the cloud tops, this material would be dispersed by local winds, creating the streaky pattern of absorption.
The bright areas are therefore thought to correspond to regions that do not contain the absorber, while the dark areas do. As Cottini indicated in a recent NASA press release, a CubeSat mission would be ideal for investigating these possibilities:
“Since the maximum absorption of solar energy by Venus occurs in the ultraviolet, determining the nature, concentration, and distribution of the unknown absorber is fundamental. This is a highly-focused mission – perfect for a CubeSat application.”
CubeSats being deployed from the International Space Station during Expedition 47. Image: NASA
Such a mission would leverage recent improvements in miniaturization, which have allowed for the creation of smaller, box-sized satellites that can do the same jobs as larger ones. For its mission, CUVE would rely on a miniaturized ultraviolet camera and a miniature spectrometer (allowing for analysis of the atmosphere in multiple wavelengths) as well as miniaturized navigation, electronics, and flight software.
Another key component of the CUVE mission is the carbon nanotube mirror, which is part of a miniature telescope the team is hoping to include. This mirror, which was developed by Peter Chen (a contractor at NASA Goddard), is made by pouring a mixture of epoxy and carbon nanotubes into a mold. This mold is then heated to cure and harden the epoxy, and the mirror is coated with a reflective material of aluminum and silicon dioxide.
In addition to being lightweight and highly stable, this type of mirror is relatively easy to produce. Unlike conventional lenses, it does not require polishing (an expensive and time-consuming process) to remain effective. As Cottini indicated, these and other developments in CubeSat technology could facilitate low-cost missions capable of piggy-backing on existing missions throughout the Solar System.
“CUVE is a targeted mission, with a dedicated science payload and a compact bus to maximize flight opportunities such as a ride-share with another mission to Venus or to a different target,” she said. “CUVE would complement past, current, and future Venus missions and provide great science return at lower cost.”
A cubesat structure, 1U in size. Credit: Wikipedia Commons/Svobodat
The team anticipates that in the coming years, the probe will be sent to Venus as part of a larger mission’s secondary payload. Once it reaches Venus, it will be launched and assume a polar orbit around the planet. They estimate that it would take CUVE one-and-a-half years to reach its destination, and the probe would gather data for a period of about six months.
If successful, this mission could pave the way for other low-cost, lightweight satellites that are deployed to other Solar bodies as part of a larger exploration mission. Cottini and her colleagues will also be presenting their proposal for the CUVE satellite and mission at the 2017 European Planetary Science Congress, which is being held from September 17th – 22nd in Riga, Latvia.
The technique of gravitational lensing relies on the presence of a large cluster of matter between the observer and the object to magnify light coming from that object. Credit: NASA
The observable Universe is an extremely big place, measuring an estimated 91 billion light-years in diameter. As a result, astronomers are forced to rely on powerful instruments to see faraway objects. But even these are sometimes limited, and must be paired with a technique known as gravitational lensing. This involves relying on a large distribution of matter (a galaxy or star) to magnify the light coming from a distant object.
Using this technique, an international team led by researchers from the California Institute of Technology’s (Caltech) Owens Valley Radio Observatory (OVRO) were able to observe jets of hot gas spewing from a supermassive black hole in a distant galaxy (known as PKS 1413 + 135). The discovery provided the best view to date of the types of hot gas that are often detected coming from the centers of supermassive black holes (SMBH).
The research findings were described in twostudies that were published in the August 15th issue of The Astrophysical Journal. Both were led by Harish Vedantham, a Caltech Millikan Postdoctoral Scholar, and were part of an international project led by Anthony Readhead – the Robinson Professor of Astronomy, Emeritus, and director of the OVRO.
The Owens Valley Radio Observatory (OVRO) – located near Bishop, California – is one of the largest university-operated radio observatories in the world. Credit: ovro.caltech.edu
This OVRO project has been active since 2008, conducting twice-weekly observations of some 1,800 active SMBHs and their respective galaxies using its 40-meter telescope. These observations have been conducted in support of NASA’s Fermi Gamma-ray Space Telescope, which has be conducting similar studies of these galaxies and their SMBHs during the same period.
As the team indicated in their two studies, these observations have provided new insight into the clumps of matter that are periodically ejected from supermassive black holes, as well as opening up new possibilities for gravitational lensing research. As Dr. Vedantham indicated in a recent Caltech press statement:
“We have known about the existence of these clumps of material streaming along black hole jets, and that they move close to the speed of light, but not much is known about their internal structure or how they are launched. With lensing systems like this one, we can see the clumps closer to the central engine of the black hole and in much more detail than before.”
While all large galaxies are believed to have an SMBH at the center of their galaxy, not all have jets of hot gas accompanying them. The presence of such jets are associated with what is known as an Active Galactic Nucleus (AGN), a compact region at the center of a galaxy that is especially bright in many wavelengths – including radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray radiation.
Illustration showing the likely configuration of a gravitational lensing system discovered by OVRO. Credit: Anthony Readhead/Caltech/MOJAVE
These jets are the result of material that is being pulled towards an SMBH, some of which ends up being ejected in the form of hot gas. Material in these streams travels at close to the speed of light, and the streams are active for periods ranging from 1 to 10 million years. Whereas most of the time, the jets are relatively consistent, every few years, they spit out additional clumps of hot matter.
Back in 2010, the OVRO researchers noticed that PKS 1413 + 135’s radio emissions had brightened, faded and then brightened again over the course of a year. In 2015, they noticed the same behavior and conducted a detailed analysis. After ruling out other possible explanations, they concluded that the overall brightening was likely caused by two high-speed clumps of material being ejected from the black hole.
These clumps traveled along the jet and became magnified when they passed behind the gravitational lens they were using for their observations. This discovery was quite fortuitous, and was the result of many years of astronomical study. As Timothy Pearson, a senior research scientist at Caltech and a co-author on the paper, explained:
“It has taken observations of a huge number of galaxies to find this one object with the symmetrical dips in brightness that point to the presence of a gravitational lens. We are now looking hard at all our other data to try to find similar objects that can give a magnified view of galactic nuclei.”
Artist’s representation of an active galactic nucleus (AGN) at the center of a galaxy. Credit: NASA/CXC/M.Weiss
What was also exciting about the international team’s observations was the nature of the “lens” they used. In the past, scientists have relied on massive lenses (i.e. entire galaxies) or micro lenses that consisted of single stars. However, the team led by Dr. Vedantham and Dr. Readhead relied on an what they describe as a “milli-lens” of about 10,000 solar masses.
This could be the first study in history that relied on an intermediate-sized lens, which they believe is most likely a star cluster. One of the advantages of a milli-sized lens is that it is not large enough to block out the entire source of light, making it easier to spot smaller objects. With this new gravitational lensing system, it is estimated that astronomers will be able to observe clumps at scales about 100 times smaller than before. As Readhead explained:
“The clumps we’re seeing are very close to the central black hole and are tiny – only a few light-days across. We think these tiny components moving at close to the speed of light are being magnified by a gravitational lens in the foreground spiral galaxy. This provides exquisite resolution of a millionth of a second of arc, which is equivalent to viewing a grain of salt on the moon from Earth.”
What’s more, the researchers indicate that the lens itself is of scientific interest, for the simple reason that not much is known about objects in this mass range. This potential star cluster could therefore act as a sort of laboratory, giving researchers a chance to study gravitational milli-lensing while also providing a clear view of the nuclear jets streaming from active galactic nuclei.
Image of the 40-meter telescope of the Owens Valley Radio Observatory (OVRO), located near Bishop, California. Credit: Anthony Readhead/Caltech
Looking ahead, the team hopes to confirm the results of their studies using another technique known as Very-Long Baseline Interferometry (VLBI). This will involve radio telescopes from around the world taking detailed images of PKS 1413 + 135 and the SMBH at its center. Given what they have observed so far, it is likely that this SMBH will spit out another clump of matter in a few years time (by 2020).
Vedantham, Readhead and their colleagues plan to be ready for this event. Spotting this next clump would not only validate their recent studies, it would also validate the milli-lens technique they used to conduct their observations. As Readhead indicated, “We couldn’t do studies like these without a university observatory like the Owens Valley Radio Observatory, where we have the time to dedicate a large telescope exclusively to a single program.”
The view of the corona during totality? This computational model was derived from NASA SDO data during the last solar rotation. Credit: Predictive Science Inc.
Totality! The view during the November 2012 total solar eclipse. Image credit and copyright: Sharin Ahmad (@Shahgazer)
It’s hard to believe: we’re now just one short weekend away from the big ticket astronomical event for 2017, as a total solar eclipse is set to cross over the contiguous United States on Monday, August 21st.
Celestial mechanics is a sure thing in this Universe, a certainty along with death and taxes that you can bet on. But there are still a few key question marks leading up to eclipse day, things that we can now finally make intelligent assumptions about a few days out.
Although totality slices through the U.S., partial phases of the eclipse touch on every continent except Antarctica and Australia. Credit: Michael Zeiler/The Great American Eclipse.
First up is solar activity. If you’re like us, you’ll be showing off the Sun in both visible and hydrogen alpha as the Moon begins making its slow hour long creep across the disk of Sol. First, the good news: sunspot active region AR 2671 made its Earthward debut on Tuesday August 15th, and will most likely stick around until eclipse day. The bad news is, it most likely won’t have lots of friends, as solar cycle #24 begins its long slow ebb towards the solar minimum in 2019-2020. Likewise, I wouldn’t expect to see any magnificent sprouting red prominences in the solar chromosphere in the seconds bracketing totality, though we could always be pleasantly surprised.
The Earthward face of Sol as of August 17, four days before totality. Sunspot AR 2671 is robust and growing in complexity. Credit: NASA/SDO/HMI
How will the white hot corona appear during totality? This is the signature climax of any total solar eclipse: veteran umbraphiles can actually glance at a photo of totality and tell you which eclipse it was from, just on the shape of the corona. The National Solar Observatory released a model of what that Sun’s magnetosphere was doing one Carrington rotation (27 days) prior to the eclipse on July 25th, a pretty good predictor of the corona might look like during those fleeting moments of totality:
The shape of the field lines of the solar corona, one rotation prior to the August 21st total solar eclipse. Credit: The National Solar Observatory.
NASA will be chasing the umbra of the Moon with two converted W-57 aircraft during the eclipse, hoping to unlock the “coronal heating paradox,” image Mercury in the infrared, and hunt for elusive Vulcanoid asteroids near the eclipsed Sun.
The view of the corona during totality? This computational model was derived from NASA SDO data during the last solar rotation. Credit: Predictive Science Inc.
The corona is about twice as bright as a Full Moon, and its interface with the solar wind extends out past the Earth. The very onset of totality is like the footstep of a giant passing over the landscape, as the door of reality is suddenly ripped open, revealing the span of the glittering solar system at midday. Keep your eyes peeled for Mercury, Venus, Mars, Jupiter and twinkling Regulus tangled up in the corona, just a degree from the Sun-Moon pair:
The line up of the planets, bright stars and the eclipsed Sun during totality at 2:37 PM EDT as seen from Franklin, North Carolina. Credit: Stellarium.
Also, be sure to scan the local horizon for a strange 360 degree sunset as you stand in the umbra of the Moon. An “eclipse wind” may kick up, as temperatures plummet and nature is fooled by the false dawn, causing chickens to come home to roost and nocturnal animals to awaken. I dare you to blink. Totality can affect the human heart as well, causing tears to cries of surprise.
Here’s an interesting, though remote, possibility. Could a sungrazing “eclipse comet” photo bomb the show? Karl Battams (@SungrazerComets) raises this question on a recent Planetary Society blog post. Battams works with the Solar Heliospheric Observatory (SOHO), which has discovered an amazing 3,358 comets crossing the field of view of its LASCO imagers since 1995. Comets have been discovered during eclipses before, most notably in 1882 and 1948. To be sure, it’s a remote possibility this late in the game, but Battams promises to give us one last quick look via SOHO the morning of the eclipse on his Twitter feed to see if any cometary interlopers are afoot.
The possible search area for Kreutz group sungrazers during the August 21st eclipse. Credit: Karl Battams.
Now, on to the biggest question mark going into this eclipse weekend: what’s the weather going to be like during the eclipse? This is the ever-dominating factor on everyone’s mind leading up to eclipse day. Keep in mind, the partial phases are long; even a partly cloudy sky will afford occasional glimpses of the Sun during the partial phases of an eclipse. Totality, however, is fleeting – 2 minutes and 40 seconds near Hopkinsville, Kentucky and less for most – meaning even a solitary cumulus cloud drifting across the Sun at the wrong moment can spoil the view. No weather model can predict the view of the sky to that refined a level. And while best bets are still out west, lingering forest fires in Oregon are a concern, along early morning fog on the western side of the Cascade Mountains. Michael Zeiler over at The Great American Eclipse has been providing ESRI models of the cloud cover over the eclipse path for Monday… here’s the outlook as of Thursday, August 17th:
A look at cloud cover prospects over the eclipse path as of August 17. Credit: Michael Zeiler/Great American Eclipse/ESRI.
Computer models should begin to come into agreement this weekend, a good sign that we know what the weather is going to do Monday. Needless to say, a deviation from the standard climate models could send lots of folks scrambling down the path at the last minute… I’ve heard of folks with up to 5 (!) separate reservations along the path of totality, no lie…
The NOAA also has a fine site dedicated to weather and cloud coverage across the path come eclipse day, and Skippy Sky is another great resource aimed at sky viewing and cloud cover.
Clouded out? The good folks at the Virtual Telescope have got you covered, with a webcast for the total solar eclipse starting at 17:00 UT/1:00 PM EDT:
Credit: The Virtual Telescope Project.
Of course, you’ll need to use proper solar viewing methods during all partial phases of the eclipse. This means either using a telescope with a filter specifically designed to look at the Sun, a pin hole projector, or certified ISO 12312-2 eclipse glasses. If you’ve got an extra pair, why not convert them into a safe filter for those binoculars or a small telescope as well:
Also be wary of heatstroke, standing out showing folks the partially eclipsed Sun for an hour or more. It is August, and heat exhaustion can come on in a hurry. Be sure you have access to shade and stay cool and hydrated in the summer Sun.
Finally, eyes from space will be watching the eclipse from the International Space Station as well. Looking out at Monday, the ISS will pass through the penumbra of the Moon and see partial phases of the eclipse three times centered on 16:32, 18:20, and 20:00 Universal Time. The center time is particularly intriguing, as astros have a chance to see the dark umbral shadow of the Moon crossing the central U.S. This also means that eclipse viewers on planet Earth around southern Illinois might want to glance northward briefly, to spy the ISS during totality. Also, viewers along a line along southern central Canada will have a chance to catch an ISS transit across the face of the partially eclipsed Sun around the same time. Check CALSky for details.
Three passes of the International Space Station versus the path of of totality. The inset shows the view of the partially eclipsed Sun as seen from the ISS. Credit: NASA/JSC.
We’ll be at the Pisgah Astronomical Research Institute in southwestern North Carolina, for a glorious 104 seconds of totality. We expect to be out of wifi range come eclipse day, but we’ll tweet out key eclipse milestones as @Astroguyz. We also plan on writing up the eclipse experience with state-by-state testimonials post eclipse.
Read more about the August 21st total solar eclipse and the true tale of Edison’s chickens and the 1878 eclipse in our free e-book: 101 Astronomical Events for 2017.
Stars and the limb of Earth seen in the background of the International Space Station on July 29, 2017. Credit: NASA/Jack Fischer.
I’ve often been asked the question, “Can the astronauts on the Space Station see the stars?” Astronaut Jack Fischer provides an unequivocal answer of “yes!” with a recent post on Twitter of a timelapse he took from the ISS. Fischer captured the arc of the Milky Way in all its glory, saying it “paints the heavens in a thick coat of awesome-sauce!”
Can you see stars from up here? Oh yeah baby! Check out the Milky Way as it spins & paints the heavens in a thick coat of awesome-sauce! pic.twitter.com/MsXeNHPxLF
But, you might be saying, “how can this be? I thought the astronauts on the Moon couldn’t see any stars, so how can anyone see stars in space?”
John W. Young on the Moon during Apollo 16 mission. Charles M. Duke Jr. took this picture. The LM Orion is on the left. April 21, 1972. Credit: NASA
It is a common misconception that the Apollo astronauts didn’t see any stars. While stars don’t show up in the pictures from the Apollo missions, that’s because the camera exposures were set to allow for good images of the bright sunlit lunar surface, which included astronauts in bright white space suits and shiny spacecraft. Apollo astronauts reported they could see the brighter stars if they stood in the shadow of the Lunar Module, and also they saw stars while orbiting the far side of the Moon. Al Worden from Apollo 15 has said the sky was “awash with stars” in the view from the far side of the Moon that was not in daylight.
Just like stargazers on Earth need dark skies to see stars, so too when you’re in space.
The cool thing about being in the ISS is that astronauts experience nighttime 16 times a day (in 45 minute intervals) as they orbit the Earth every 90 minutes, and can have extremely dark skies when they are on the “dark” side of Earth. Here’s another recent picture from Fischer where stars can be seen:
Twinkle, twinkle, little star… Up above the world so high Like a diamond in the sky… pic.twitter.com/8H7CshyP0p
For stars to show up in any image, its all about the exposure settings. For example, if you are outside (on Earth) on a dark night and can see thousands of stars, if you just take your camera or phone camera and snap a quick picture, you’ll just get a darkness. Earth-bound astrophotographers need long-exposure shots to capture the Milky Way. Same is true with ISS astronauts: if they take long-exposure shots, they can get stunning images like this one:
This long exposure image of the night sky over Earth was taken on August 9, 2015 by a member of the Expedition 44 crew on board the International Space Station. Credit: NASA.
This image, set to capture the bright solar arrays and the rather bright Earth (even though its in twilight) reveals no stars:
Sometimes you look out the window and it just takes your breath away from how beautiful Earth is. Today is one of those times… #EarthShapespic.twitter.com/53UqL9BFH1
The SpaceX Dragon CRS-12 cargo craft is now attached to the International Space Station after arriving on Aug. 16, 2017. It delivered over 3 tons of science and supplies to the six person Expedition 52 crew. Credit: NASA TV
The SpaceX Dragon CRS-12 cargo craft is now attached to the International Space Station after arriving on Aug. 16, 2017. It delivered over 3 tons of science and supplies to the six person Expedition 52 crew. Credit: NASA TV
While Dragon maneuvered in ever so slowly guided by lasers, NASA astronaut Jack Fischer and ESA (European Space Agency) astronaut Paolo Nespoli carefully extended the stations robotic arm to reach out and grapple the gumdrop shaped capsule.
They deftly captured the Dragon CRS-12 resupply spacecraft slightly ahead of schedule at 6:52 a.m. EDT with the station’s 57.7-foot-long (17.6 meter-long) Canadian-built robotic arm while working at a robotics work station in the seven windowed domed Cupola module.
The SpaceX Dragon cargo craft is pictured approaching the International Space Station on Wednesday morning Aug. 16, 2017. Credit: NASA
The million pound orbiting outpost was traveling over the Pacific Ocean north of New Zealand at the time of capture.
Liftoff of the SpaceX Falcon 9 took place precisely on time 2 days earlier with ignition of the 9 Merlin 1D first stage engines from seaside pad 39A at NASA’s Kennedy Space Center in Florida today (Aug. 14) at 12:31 p.m. EDT (1631 GMT).
SpaceX launched its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Ken Kremer/Kenkremer.com
The two stage Falcon 9 stands 213-foot-tall (65-meter-tall). The combined output of the 9 Merlin 1D first stage engines generates 1.7 million pounds of liftoff thrust, fueled by liquid oxygen and RP-1 propellants.
SpaceX launched its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Ken Kremer/Kenkremer.com
See an exciting gallery of launch imagery and videos including the thrilling ground landing of the 156 foot tall first stage booster back at Cape Canaveral at Landing Zone-1 – from this author and several space colleagues.
SpaceX launched its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Ken Kremer/Kenkremer.com
Monday’s picture perfect lunchtime liftoff of the unmanned SpaceX CRS-12 Dragon cargo freighter bound for the ISS and loaded with over 3 tons of science, research hardware and supplies including a hefty cosmic ray detector named ISS-CREAM, medical research experiments dealing with Parkinson’s disease, lung and heart tissue, vegetable seeds, dozens of mice and much more – came off without a hitch.
Ground controllers then carried out the remainder of the work to berth the SpaceX Dragon cargo spacecraft at the Earth facing port on the Harmony module of the International Space Station at 9:07 a.m. EDT.
This illustration of the International Space Station shows the current configuration with four visiting vehicle spaceships parked at the space station including the SpaceX Dragon CRS-12 cargo craft that arrived Aug. 16, 2017, the Progress 67 resupply ship and two Soyuz crew ships. Credit: NASA
The crew was perhaps especially eager for this Dragons arrival because tucked inside the more than 3 tons of cargo was a stash of delicious ice cream treats.
“The small cups of chocolate, vanilla and birthday cake-flavored ice cream are arriving in freezers that will be reloaded with research samples for return to Earth when the Dragon spacecraft departs the station mid-September,” said NASA.
Indeed the crew did indeed open the hatches today, early than planned, a few hours after arrival and completion of the requisite safety and leak checks.
The SpaceX Dragon cargo craft is pictured approaching the International Space Station on Wednesday morning Aug. 16, 2017. Credit: NASA TV
The whole sequence was broadcast on NASA TV that began live arrival coverage at 5:30 a.m showing numerous stunning video sequences of the rendezvous and grappling often backdropped by our precious Home Planet.
The current multinational Expedition 52 crew serving aboard the ISS comprises of Flight Engineers Paolo Nespoli from ESA, Jack Fischer, Peggy Whitson and Randy Bresnik of NASA and Sergey Ryazanskiy and Commander Fyodor Yurchikhin of Roscosmos.
Launch of SpaceX Falcon on Dragon CRS-12 mission to the ISS from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Julian Leek
The Dragon resupply ship dubbed Dragon CRS-12 counts as SpaceX’s twelfth contracted commercial resupply services (CRS) mission to the International Space Station for NASA since 2012.
SpaceX holds a NASA commercial resupply services (CRS) contract that includes up to 20 missions under the original CRS-1 contract.
The 20-foot high, 12-foot-diameter Dragon CRS-12 vessel is carrying 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. 20 mice are also onboard. This will support dozens of the 250 research investigations and experiments being conducted by Expedition 52 and 53 crew members.
The Expedition 52 crew poses for a unique portrait. Pictured clockwise from top right are, Flight Engineers Paolo Nespoli, Jack Fischer, Peggy Whitson, Sergey Ryazanskiy, Randy Bresnik and Commander Fyodor Yurchikhin. Credit: NASA/Roscosmos/ESA
Video Caption: CRS-12 launch from Pad 39A on a Falcon 9 rocket. Pad camera views from the launch of the CRS-12 mission carrying 6415 pounds of supplies and equipment to the International Space Station on August 14, 2017. Credit: Jeff Seibert
The SpaceX Falcon 9/Dragon CRS-12 launch was the first of a rapid fire sequence of a triad of launches along the Florida Space Coast over the next 11 days of manmade wonder – Plus a Total Solar ‘Eclipse Across America’ natural wonder sandwiched in between !!
Launch of SpaceX Falcon on Dragon CRS-12 mission to the ISS from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Julian Leek
Watch for Ken’s continuing onsite CRS-12, TRDS-M, and ORS 5 and NASA 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.
Ground landing of SpaceX Falcon 9 first stage at Landing Zone-1 (LZ-1) after SpaceX launched its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida from pad 39A at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Ken Kremer/Kenkremer.com
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Learn more about the upcoming ULA Atlas TDRS-M NASA comsat on Aug. 18, 2017 , SpaceX Dragon CRS-12 resupply launch to ISS on Aug. 14, Solar Eclipse, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
Aug 17-18: “TDRS-M NASA comsat, SpaceX CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
Ground landing of SpaceX Falcon 9 first stage at Landing Zone-1 (LZ-1) after SpaceX launched its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida from pad 39A at 12:31 p.m. EDT on Monday, Aug. 14, 2017. Credit: Ken Kremer/Kenkremer.comBlastoff of SpaceX Dragon CRS12 on its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017 as seen from the VAB roof. Credit: Ken Kremer/Kenkremer.comBlastoff of SpaceX Dragon CRS12 on its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017 as seen from the VAB roof. Credit: Ken Kremer/Kenkremer.comBlastoff of SpaceX Dragon CRS12 on its 12th resupply mission to the International Space Station from NASA’s Kennedy Space Center in Florida at 12:31 p.m. EDT on Monday, Aug. 14, 2017 as seen from the VAB roof. Credit: Ken Kremer/Kenkremer.com
A Hubble image of the galaxy cluster Abell 1689, which acts as a lens to focus the light from much more distant galaxies, including some very dusty star-forming galaxies in the early universe (seen as the nearly point-like blue smudges in this image). Credit: NASA-Hubble
In their pursuit of learning how our Universe came to be, scientists have probed very deep into space (and hence, very far back in time). Ultimately, their goal is to determine when the first galaxies in our Universe formed and what effect they had on cosmic evolution. Recent efforts to locate these earliest formations have probed to distances of up to 13 billion light-years from Earth – i.e. about 1 billion years after the Big Bang.
From this, scientist are now able to study how early galaxies affected matter around them – in particular, the reionization of neutral atoms. Unfortunately, most early galaxies are very faint, which makes studying their interiors difficult. But thanks to a recent survey conducted by an international team of astronomers, a more luminous, massive galaxy was spotted that could provide a clear look at how early galaxies led to reionization.
Illustration of the depth by which Hubble imaged galaxies in prior Deep Field initiatives, in units of the Age of the Universe. Credit: NASA and A. Feild (STScI)
In accordance with Big Bang model of cosmology, reionization refers to the process that took place after the period known as the “Dark Ages”. This occurred between 380,000 and 150 million years after the Big Bang, where most of the photons in the Universe were interacting with electrons and protons. As a result, the radiation of this period is undetectable by our current instruments – hence the name.
Just prior to this period, the “Recombination” occurred, where hydrogen and helium atoms began to form. Initially ionized (with no electrons bound to their nuclei) these molecules gradually captured ions as the Universe cooled, becoming neutral. During the period that followed – i.e. between 150 million to 1 billion years after the Big Bang – the large-scale structure of the Universe began to form.
Intrinsic to this was the process of reionization, where the first stars and quasars formed and their radiation reionized the surrounding Universe. It is therefore clear why astronomers want to probe this era of the Universe. By observing the first stars and galaxies, and what effect they had on the cosmos, astronomers will get a clearer picture of how this early period led to the Universe as we know it today.
Luckily for the research team, the massive, star-forming galaxies of this period are known to contain a great deal of dust. While very faint in the optical band, these galaxies emit strong radiation at submillimeter wavelengths, which makes them detectable using today’s advanced telescopes – including the South Pole Telescope (SPT), the Atacama Pathfinder Experiment (APEX), and Atacama Large Millimeter Array (ALMA).
NASA’s Spitzer Space Telescope captured this stunning infrared image of the center of the Milky Way Galaxy, where the black hole Sagitarrius A resides. Image: NASA/JPL-Caltech
For the sake of their study, Strandet and Weiss relied on data from the SPT to detect a series of dusty galaxies from the early Universe. As Maria Strandet and Axel Weiss of the Max Planck Institute for Radio Astronomy (and the lead author and co-authors on the study, respectively) told Universe Today via email:
“We have used light of about 1 mm wavelength, which can be observed by mm telescopes like SPT, APEX or ALMA. At this wavelength the photons are produced by the thermal radiation of dust. The beauty of using this long wavelength is, that for a large redshift range (look back time), the dimming of galaxies [caused] by increasing distance is compensated by the redshift – so the observed intensity is independent of the redshift. This is because, for higher redshift galaxies, one is looking at intrinsically shorter wavelengths (by (1+z)) where the radiation is stronger for a thermal spectrum like the dust spectrum.”
This was followed by data from ALMA, which the team used to determine the distance of the galaxies by looking at the redshifted wavelength of carbon monoxide molecules in their interstellar mediums (ISM). From all the data they collected, they were able to constrain the properties of one of these galaxies – SPT0311-58 – by observing its spectral lines. In so doing, they determined that this galaxy existed just 760 million years after the Big Bang.
“Since the signal strength at 1mm is independent of the redshift (look back time), we do not have an a priori clue if an object is relatively near (in the cosmological sense) or at the epoch of reionization,” they said. “That is why we undertook a large survey to determine the redshifts via the emission of molecular lines using ALMA. SPT0311-58 turns out to be the highest redshift object discovered in this survey and in fact the most distant massive dusty star-forming galaxy so far discovered.”
The Hubble Ultra Deep Field seen in ultraviolet, visible, and infrared light. Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)
From their observations, they also determined that SPT0311-58 has a mass of about 330 billion Solar-masses, which is about 66 times as much as the Milky Way Galaxy (which has about 5 billion Solar-masses). They also estimated that it is forming new stars at a rate of several thousand per year, which could as be the case for neighboring galaxies that are dated to this period.
This rare and distant object is one of the best candidates yet for studying what the early Universe looked like and how it has evolved since. This in turn will allow astronomers and cosmologists to test the theoretical basis for the Big Bang Theory. As Strandet and Weiss told Universe Today about their discovery:
“These objects are important to understanding the evolution of galaxies as a whole since the large amounts of dust already present in this source, only 760 million years after the Big Bang, means that it is an extremely massive object. The mere fact that such massive galaxies already existed when the Universe was still so young puts strong constraints on our understanding of galaxy mass buildup. Furthermore the dust needs to form in a very short time, which gives additional insights on the dust production from the first stellar population.”
The ability to look deeper into space, and farther back in time, has led to many surprising discoveries of late. And these have in turn challenged some of our assumptions about what happened in the Universe, and when. And in the end, they are helping scientists to create a more detailed and complete account of cosmic evolution. Someday soon, we might even be able to probe the earliest moments in the Universe, and watch creation in action!
Artist's impression of a system of exoplanets orbiting a low mass, red dwarf star. Credit: NASA/JPL
Studies of low-mass, ultra-cool and ultra-dim red dwarf stars have turned up a wealth of extra-solar planets lately. These include the discoveries of a rocky planet orbiting the closest star to the Solar System (Proxima b) and a seven-planet system just 40 light years away (TRAPPIST-1). In the past few years, astronomers have also detected candidates orbiting the stars Gliese 581, Innes Star, Kepler 42, Gliese 832, Gliese 667, Gliese 3293, and others.
The majority of these planets have been terrestrial (i.e. rocky) in nature, and many were found to orbit within their star’s habitable zone (aka. “goldilocks zone”). However the question whether or not these planets are tidally-locked, where one face is constantly facing towards their star has been an ongoing one. And according to a new study from the University of Washington, tidally-locked planets may be more common than previously thought.
The study – which is available online under the title “Tidal Locking of Habitable Exoplanets” – was led by Rory Barnes, an assistant professor of astronomy and astrobiology at the University of Washington. Also a theorist with the Virtual Planetary Laboratory, his research is focused on the formation and evolution of planets that orbit in and around the “habitable zones” of low-mass stars.
Tidal locking results in the Moon rotating about its axis in about the same time it takes to orbit the Earth (left side). Credit: Wikipedia
For modern astronomers, tidal-locking is a well-understood phenomena. It occurs as a result of their being no net transfer of angular momentum between an astronomical body and the body it orbits. In other words, the orbiting body’s orbital period matches its rotational period, ensuring that the same side of this body is always facing towards the planet or star it orbits.
Consider Earth’s only satellite – the Moon. In addition to taking 27.32 days to orbit Earth, the Moon also takes 27.32 days to rotate once on its axis. This is why the Moon always presents the same “face” towards Earth, while the side that faces away is known as the “dark side”. Astronomers believe this became the case after a Mars-sized object (Theia) collided with Earth some 4.5 billion years ago.
Aside from throwing up debris that would eventually form the Moon, the impact is believed to have struck Earth at such an angle that it gave our planet an initial rotation period of 12 hours. In the past, researchers have used this 12-hour estimation of Earth’s rotation as a model for exoplanet behavior. However, prior to Barnes’ study, no systematic examinations had ever been conducted.
Looking to address this, Barnes chose to address the long-held assumption that only smaller, dimmer stars could host orbiting planets that were tidally locked. He also considered other possibilities, which included slower or faster initial rotation periods as well as variations in planet size and the eccentricity of their orbits. What he found was that previous studies had been rather limited and only made allowances for one outcome.
Tidally-locked, rocky planets are common around low-mass, M-type (red dwarf) stars, due to their close orbits. Credit: M. Weiss/CfA
As he explained in a University of Washington press statement:
“Planetary formation models, however, suggest the initial rotation of a planet could be much larger than several hours, perhaps even several weeks. And so when you explore that range, what you find is that there’s a possibility for a lot more exoplanets to be tidally locked. For example, if Earth formed with no Moon and with an initial ‘day’ that was four days long, one model predicts Earth would be tidally locked to the sun by now.”
From this, he found that potentially-habitable planets that orbit very late M-type (red dwarf) stars are likely to attain highly-circular orbits about 1 billion years after their formation. Furthermore, he found that for the majority, their orbits would be synchronized with their rotation – aka. they would be tidally-locked with their star. These findings could have significant implications for the study of exoplanets formation and evolution, not to mention habitability.
In the past, tidally-locked planets were thought to have extremes climates, thus eliminating any possibility of life. As an example, the planet Mercury experiences a 3:2 spin-orbit resonance, meaning it rotates three times on its axis for every two orbits it completes of the Sun. Because of this, a single day on Mercury lasts as long as 176 Earth days, and temperature range from 100 (-173 °C; -279 °F) to 700 K (427 °C; 800 °F) between the day side and the night side.
For a tidally-locked planets that orbit close to their stars, it was believed this situation would be even worse. However, astronomers have since come to speculate that the presence of an atmosphere around these planets could redistribute temperature across their surfaces. Unlike Mercury, which has no atmosphere and experiences no wind, these planets could maintain temperatures that would be supportive to life.
Artist’s impression of a “Earth-like” planet orbiting a nearby red dwarf star. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
In any case, this study is one of many that is putting constraints on recent exoplanet discoveries. This is especially important given that the detection and study of extra-solar planets is still in its infancy, and limited to largely indirect methods. In other words, astronomers make estimates of a planet’s size, composition and whether or not it has an atmosphere based on transits and the influence these planets have on their stars.
In the coming years, next-generations missions like the James Web Space Telescope and the Transiting Exoplanet Survey Satellites (TESS) are expected to improve this situation drastically. In addition to conducting more detailed observations on existing discoveries, they are also expected to uncover a wealth of more planets. If Barnes’ study is correct, the majority of those found will be tidally-locked, but that need not mean they are uninhabitable.
Prof. Barnes paper was accepted for publication by the journal Celestial Mechanics and Dynamical Astronomy. The research was funded by a NASA grant through the Virtual Planetary Laboratory.
