An artist's illustration of the Falcon Heavy rocket. The Falcon Heavy has 3 engine cores, each one containing 9 Merlin engines. Image: SpaceX
Move over Arianespace and United Launch Alliance. SpaceX’s Falcon Heavy rocket is set for its maiden launch this November. The long-awaited Falcon Heavy should be able to outperform both the Ariane 5 and the ULA Delta-4 Heavy, at least in some respects.
The payload for the maiden voyage is uncertain so far. According to Gwynne Shotwell, SpaceX’s President and CEO, a number of companies have expressed interest in being on the first flight. Shotwell has also said that it might make more sense for SpaceX to completely own their first flight, without the pressure to keep a client happy. But a satellite payload for the first launch hasn’t been ruled out.
Delivering a payload into orbit is what the Falcon Heavy, and its competitors the Ariane5 and the ULA Delta-4 Heavy, are all about. Since one of the main competitive points of the Falcon Heavy is its ability to put larger payloads into geo-stationary orbits, accomplishing that feat on its first flight would be a great coming out party for the Falcon Heavy.
This artist’s illustration of the Falcon Heavy shows the rocket in flight prior to releasing its two side boosters. Image: SpaceX
SpaceX has promised that it will make its first Falcon Heavy launch useful. They say that they will use the flight either to demonstrate to its commercial customers the rocket’s capability to deliver a payload to GTO, or to demonstrate to national security interests its ability to meet their needs.
National security satellites require different capabilities from launch vehicles than do commercial communication satellites. Since these spacecraft are top secret, and are used to spy on communications, they need to be placed directly into their GTO, avoiding the lower-altitude transfer orbit of commercial satellites.
The payload for the first launch of the Falcon Heavy is not the only thing in question. There’s some question whether the November launch date can be achieved, since the Falcon Heavy has faced some delays in the past.
The inaugural flight for the big brother to the Falcon 9 was originally set for 2013, but several delays have kept bumping the date. One of the main reasons for this was the state of the Falcon 9. SpaceX was focussed on Falcon 9’s landing capabilities, and put increased manpower into that project, at the expense of the Falcon Heavy. But now that SpaceX has successfully landed the Falcon 9, the company seems poised to meet the November launch date for the Heavy.
One of the main attractions to the Falcon Heavy is its ability to deliver larger payloads to geostationary orbit (GEO). This is the orbit occupied by communications and weather satellites. These types of satellites, and the companies that build and operate them, are an important customer base for SpaceX. SpaceX claims that the Falcon Heavy will be able to place payloads of 22,200 kg (48,940 lbs) to GEO. This trumps the Delta-4 Heavy (14,200 kg/31,350 lbs) and the Ariane5 (max. 10,500 kg/23,100 lbs.)
There’s a catch to these numbers, though. The Falcon Heavy will be able to deliver larger payloads to GEO, but it’ll do it at the expense of reusability. In order to recover the two side-boosters and central core stage for reuse, some fuel has to be held in reserve. Carrying that fuel and using it for recovery, rather than burning it to boost larger payloads, will reduce the payload for GEO to about 8,000 kg (17,637 lbs.) That’s significantly less than the Ariane 5, and the upcoming Ariane 6, which will both compete for customers with the Falcon Heavy.
The Falcon Heavy is essentially four Falcon 9 rockets configured together to create a larger rocket. Three Falcon 9 first stage boosters are combined to generate three times as much thrust at lift-off as a single Falcon 9. Since each Falcon 9 is actually made of 9 separate engines, the Falcon Heavy will actually have 27 separate engines powering its first stage. The second stage is another single Falcon 9 second-stage rocket, consisting of a single Merlin engine, which can be fired multiple times to place payloads in orbit.
The three main boosters for the Falcon Heavy will all be built this summer, with construction of one already underway. Once complete, they will be transported from their construction facility in California to the testing facility in Texas. After that, they will be transported to Cape Canaveral.
Once at Cape Canaveral, the launch preparations will have all of the 27 engines in the first stage fired together in a hold-down firing, which will give SpaceX its first look at how all three main boosters operate together.
Eventually, if everything goes well, the Falcon Heavy will launch from Pad 39A at Cape Canaveral. Pad 39A is the site of the last Shuttle launches, and is now leased from NASA by SpaceX.
The Falcon Heavy will be the most powerful rocket around, once it’s operational. The versatility to deliver huge payloads to orbit, or to keep its costs down by recovering boosters, will make its first flight a huge achievement, whether or not it does deliver a satellite into orbit on its first launch.
The Messier 13 globular cluster, located in the Hercules constellation. Credit: Adam Block/Sid Leach/Mount Lemmon SkyCenter/University of Arizona
Welcome back to Messier Monday! Today, in our ongoing tribute to Tammy Plotner, we take a look at the M13 globular cluster, which is often referred to as the Great Globular Cluster in Hercules. Enjoy!
In the 18th century, French astronomer Charles Messier began cataloging all the “nebulous objects” he had come to find while searching the night sky. Having originally mistook these for comets, he compiled a list these objects in the hopes of preventing future astronomers from making the same mistake. In time, the list would include 100 objects, and would come to be known as the Messier Catalog to posterity.
One of these objects is M13 (aka. NGC 6205) a globular cluster located in the Hercules constellation. Located some 25,100 light-years away from Earth, this cluster is made up of 300,000 stars and occupies a region of space that measures 145 light-years in diameter. Given its sheer size and its location, it is often referred to as the “Great Hercules Cluster”.
Description:
This 11.65 billion year old formation of stars is one of the most impressive globular clusters in the northern hemisphere. Containing over 300,000 stars packed into a 145 light year sphere, the center of this glorious object is 500 times more concentrated than its outer perimeters. And out of all of those stars there stands one stranger – Barnard 29. This spectral type B2 star is a young, blue star that M13 is believed to have collected during one of its tours around the Milky Way Galaxy.
Other interesting finds include the 15 blue straggler star candidates and 10 other possible that have been spotted by the Hubble Space Telescope. The stars in the blue horizontal branch of M13 appeared to be centrally depleted relative to other stellar types and the blue stragglers in the combined sample are centrally concentrated relative to the older red giant stars.
The heart of the M13 Hercules Globular Cluster, viewed with the Hubble Space Telescope. Credit: ESA/NASA/HST
However, the Stromgren photometry work performed by Frank Grundah (et al.) suggests this is a normal occurrence in evolution. “We also note the existence of what appears to be two separate stellar populations on the horizontal branch of M13. Among other possibilities, it could arise as the result of differences in the extent to which deep mixing occurs in the precursor red giants.”
“One of the long-standing problems in modern astronomy is the curious division of Galactic globular clusters, the “Oosterhoff dichotomy,” according to the properties of their RR Lyrae stars. Here, we find that most of the lowest metallicity clusters, which are essential to an understanding of this phenomenon, display a planar alignment in the outer halo. This alignment, combined with evidence from kinematics and stellar population, indicates a captured origin from a satellite galaxy. We show that, together with the horizontal-branch evolutionary effect, the factor producing the dichotomy could be a small time gap between the cluster-formation epochs in the Milky Way and the satellite. The results oppose the traditional view that the metal-poorest clusters represent the indigenous and oldest population of the Galaxy.”
As to how old M13’s stars are, there is more than one answer. According the work of R. Glebocki (et al), stellar rotation within Messier 13 can also play a role in how the stars age. As they state in their 2000 research study, “Catalog of Projected Rotational Velocities”:
“Much theoretical and observational work about the role that rotation plays in stellar evolution has been done. Angular momentum is one of the fundamental parameters in the process of star formation as well as in early life of a star. A considerable amount of research has been done on the stellar axial rotational velocities. Clusters present unique possibility of determination of age of stars.”
Messier 13, as imaged by a DSLR camera. Credit: Wikipedia Commons/Rawastrodata
History of Observation:
M13 was originally discovered by Edmond Halley in 1714. In his notes, he wrote of the cluster: “This is but a little Patch, but it shews it self to the naked Eye, when the Sky is serene and the Moon absent.”
On June 1st, 1764, Charles Messier officially catalogued the star cluster as item 13. As he described it at the time:
“In the night of June 1 to 2, 1764, I have discovered a nebula in the girdle of Hercules, of which I am sure it doesn’t contain any star; having examined it with a Newtonian telescope of four feet and a half [FL], which magnified 60 times, it is round, beautiful & brilliant, the center brighter than the borders: One perceives it with an ordinary [non-achromatic] refractor of one foot [FL], it may have a diameter of three minutes of arc: It is accompanied by two stars, the one and the other of the ninth magnitude, situated, the one above and the other below the nebula, & little distant. I have determined its position at its passage of the Meridian, and compared with the star Epsilon Herculis; its right ascension has been concluded to be 248d 18′ 48″, and its declination 36d 54′ 44″ north. It is reported in the Philosophical Transactions, no. 347, page 390, that Mr. Halley discovered by hazard that nebula in 1714: it is, he says, almost on a straight line with Zeta and Eta according to Bayer, a bit closer to the star Zeta than to Eta, & when comparing its situation between the stars, its place is rather close to Scorpius 26d 1/2 with 57 degrees Northern [ecliptic] latitude, it is nothing but a small patch; but one sees it well without a telescope when the weather is fine, and if there is no light of the moon.”
Although Sir William Herschel would soon enough resolve it into stars and again by his son and many others, no one described the history of this object more eloquently than Admiral Smyth:
“A large cluster, or rather ball of stars, on the left buttock of Hercules, between Zeta and Eta; the place of which is differentiated from Eta Herculis, from which it lies south, a little westly, and 3deg 1/2 distant. This superb object blazes up in the centre, and has numerous outliers around its attenuated disc. It was accidentally hit upon by Halley, who says, “This is but a little patch, but it shows itself to the naked eye, when the sky is serene, and the moon absent.” The same paper, in describing this as the sixth and last of the nebulae known in 1716, wisely admits, “there are undoubtedly more of these which have not yet come to our knowledge:” ere half a century passed, Messier contributed his 80 or 90 in the Catalogue of 103; and before the close of that century WH [William Herschel] alone had added to the above 6, no fewer than 2500; and his son, in re-examining these, added 520 more! In my own refractor its appearance was something like the annexed diagram; but I agree with Dr. Nichol, that no plate can give a fitting representation of this magnificent cluster. It is indeed truly glorious, and enlarges on the eye by studying gazing. “Perhaps,” adds the Doctor, “no one ever saw it for the first time through a telescope, without uttering a shout of wonder.” This brilliant cluster was discovered by Halley in 1714; and fifty years afterwards it was examined by M. Messier, with his 4-foot Newtonian, under a power of 60, and described as round, beautiful, and brilliant; but, “ferret” as he was in these matters, he adds, “Je me suis assuré qu’elle ne contient aucune étoile.” This is rather startling, since the slightest optical aid enables the eye to resolve it into an extensive and magnificent mass of stars, with the most compressed part densely compacted and wedged together under unknown laws of aggregation. In 1787, Sir William Herschel pronounced it “a most beautiful cluster of stars, exceedingly compressed in the middle, and very rich.” It has been recently viewed in the Earl of Rosse’s new and powerful telescope, when the components were more distinctly separated, and brighter, than had been anticipated; and there were singular fringed appendages to the globular figure, branching out into the surrounding space, so as to form distinct marks among the general outliers.”
And so Messier 13 has been part of our imaginations for many years. And in 1974, a message was sent from Arecibo Observatory designed to communicate the existence of human life to hypothetical extraterrestrials. Known as the “Aricebo Message”, it was expected that this communique had a better chance of finding intelligent life since the odds of it existing within this massive cluster of stars was greater than elsewhere.
Messier 13, located in the Hercules constellation. Credit: IAU/Sky&Telescope magazine/Roger Sinnott & Rick Fienberg
Locating Messier 13:
To locate M13, all one needs to know is the “Keystone” asterism of Hercules. While this lopsided rectangle isn’t particularly bright, once you understand where to find it, you’ll be able to spot it even under relatively light-polluted skies. Both Vega (in the constellation of Lyra) and Arcturus (in Bootes) are very bright stars and the keystone is about 1/3 the distance between them.
Once you locate it, always remember that Messier 13 is on the leading western side – no matter what position Hercules may be in. By just generally aiming your binoculars in the center of the two stars on the western side, you can’t miss this big, bright globular cluster. When using a finderscope, aim slightly north of the center point and you’ll easily spot it as well. From a dark sky location, M13 can often be seen unaided as a small, fuzzy spot on the sky.
And here are the quick facts on the Great Hercules Cluster to help you get started:
Object Name: Messier 13 Alternative Designations: M13, NGC 6205, the “Great Hercules Cluster” Object Type: Class V Globular Cluster Constellation: Hercules Right Ascension: 16 : 41.7 (h:m) Declination: +36 : 28 (deg:m) Distance: 25.1 (kly) Visual Brightness: 5.8 (mag) Apparent Dimension: 20.0 (arc min)
Mercury meets the Sun in Hydrogen Alpha. Image credit and copyright: Brendan Martin @HASungazer
Lead image credit: Brendan Martin.
(Note: Awesome images are being added as they come in!)
Update: Here’s two more amazing videos of yesterday’s transit of Mercury that have come our way. First: double solar transits featuring Mercury, the International Space Station and a low flying plane right here in the skies of good old planet Earth courtesy of (who else?) Thierry Legault:
And here’s one of the very few sequences we’ve seen of the transit with foreground, captured at sunset by Gadi Eidelheit based in Israel:
And finally, check out this amazing (and mesmerizing) animation of Mercury racing across the Sun, courtesy of the Big Bear Solar Observatory!
A coronal aurora twists overhead in this photo taken early on May 8, 2016 from near Duluth, Minnesota. Credit: Bob King
Skywatchers across the northern tier of states, the Midwest and southern Canada were treated to a spectacular display of the aurora borealis last night. More may be on tap for tonight — in honor of Mother’s Day of course! Credit: Bob King
Simple choices can sometimes lead to dramatic turns of events in our lives. Before turning in for the night last night, I opened the front door for one last look at the night sky. A brighter-than-normal auroral arc arched over the northern horizon. Although no geomagnetic activity had been forecast, there was something about that arc that hinted of possibility.
It was 11:30 at the time, and it would have been easy to go to bed, but I figured one quick drive north for a better look couldn’t hurt. Ten minutes later the sky exploded. The arc subdivided into individual pillars of light that stretched by degrees until they reached the zenith and beyond. Rhythmic ripples of light – much like the regular beat of waves on a beach — pulsed upward through the display. You can’t see a chill going up your spine, but if you could, this is what it would look like.
A coronal aurora twists overhead in this photo taken around 12:15 a.m. on May 8 from near Duluth, Minn. What this photo and the others don’t show is how fast parts of the display flashed and flickered. Shapes would form, disappear and reform in seconds. Credit: Bob King
Auroras can be caused by huge eruptions of subatomic particles from the Sun’s corona called CMEs or coronal mass ejections, but they can also be sparked by holes in the solar magnetic canopy. Coronal holes show up as blank regions in photos of the Sun taken in far ultraviolet and X-ray light. Bright magnetic loops restrain the constant leakage of electrons and protons from the Sun called the solar wind. But holes allow these particles to fly away into space at high speed. Last night’s aurora traces its origin back to one of these holes.
Both a bar magnet (left) and Earth are surrounded by magnetic fields with north and south poles. Earth’s field is shaped by charged particles – electrons and protons – flowing from the sun called the solar wind. Credit: Andy Washnik (left) and NASA
The subatomic particles in the gusty wind come bundled with their own magnetic field with a plus or positive pole and a minus or negative pole. Recall that an ordinary bar magnet also has a “+” and “-” pole, and that like poles repel and opposite poles attract. Earth likewise has magnetic poles which anchor a large bubble of magnetism around the planet called the magnetosphere.
Visualization of the solar wind encountering Earth’s magnetic “defenses” known as the magnetosphere. Clouds of southward-pointing plasma are able to peel back layers of the Sun-facing bubble and stack them into layers on the planet’s nightside (center, right). The layers can be squeezed tightly enough to reconnect and deliver solar electrons (yellow sparkles) directly into the upper atmosphere to create the aurora. Credit: JPL
Field lines in the magnetosphere — those invisible lines of magnetic force around every magnet — point toward the north pole. When the field lines in the solar wind also point north, there’s little interaction between the two, almost like two magnets repelling one another. But if the cloud’s lines of magnetic force point south, they can link directly into Earth’s magnetic field like two magnets snapping together. Particles, primarily electrons, stream willy-nilly at high speed down Earth’s magnetic field lines like a zillion firefighters zipping down fire poles. They crash directly into molecules and atoms of oxygen and nitrogen around 60-100 miles overhead, which absorb the energy and then release it moments later in bursts of green and red light.
View of the eastern sky during the peak of this morning’s aurora. Credit: Bob King
So do great forces act on the tiniest of things to produce a vibrant display of northern lights. Last night’s show began at nightfall and lasted into dawn. Good news! The latest forecast calls for another round of aurora tonight from about 7 p.m. to 1 a.m. CDT (0-6 hours UT). Only minor G1 storming (K index =5) is expected, but that was last night’s expectation, too. Like the weather, the aurora can be tricky to pin down. Instead of a G1, we got a G3 or strong storm. No one’s complaining.
So if you’re looking for that perfect last minute Mother’s Day gift, take your mom to a place with a good view of the northern sky and start looking at the end of dusk for activity. Displays often begin with a low, “quiet” arc and amp up from there.
The camera recorded pale purple, red and green, but the primary color visible to the eye was green. Cameras capture far more color than what the naked eye sees because even faint colors increase in intensity during a time exposure. Details: ISO 800, f/2.8, 13 seconds. Credit: Bob King
Aurora or not, tomorrow features a big event many of us have anticipated for years — the transit of Mercury. You’ll find everything you’ll need to know in this earlier story, but to recap, Mercury will cross directly in front of the Sun during the late morning-early evening for European observers and from around sunrise (or before) through late morning-early afternoon for skywatchers in the Americas. Because the planet is tiny and the Sun deadly bright, you’ll need a small telescope capped with a safe solar filter to watch the event. Remember, never look directly at the Sun at any time.
Nov. 15, 1999 transit of Mercury photographed in UV light by the TRACE satellite. Credit: NASA
If you’re greeted with cloudy skies or live where the transit can’t be seen, be sure to check out astronomer Gianluca Masi’s live stream of the event. He’ll hook you up starting at 11:00 UT (6 a.m. CDT) tomorrow.
The table below includes the times across the major time zones in the continental U.S. for Monday May 9:
All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com
All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com
NASA GODDARD SPACE FLIGHT CENTER, MD – It’s Mesmerizing ! That’s the overwhelming feeling expressed among the fortunate few setting their own eyeballs on the newly exposed golden primary mirror at the heart of NASA’s mammoth James Webb Space Telescope (JWST) – a sentiment shared by the team building the one-of-its-kind observatory and myself during a visit this week by Universe Today.
“The telescope is cup up now [concave]. So you see it in all its glory!” said John Durning, Webb Telescope Deputy Project Manager, in an exclusive interview with Universe Today at NASA’s Goddard Space Flight Center on Tuesday, May 3, after the covers were carefully removed just days ago from all 18 primary mirror segments and the structure was temporarily pointed face up.
“The entire mirror system is checked out, integrated and the alignment has been checked.”
Up close side-view of newly exposed gold coated primary mirrors installed onto mirror backplane holding structure of NASA’s James Webb Space Telescope inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms. Credit: Ken Kremer/kenkremer.com
It’s a banner year for JWST at Goddard where the engineers and technicians are well into the final assembly and integration phase of the optical and science instrument portion of the colossal observatory that will revolutionize our understanding of the cosmos and our place it in. And they are moving along at a rapid pace.
JWST is the scientific successor to NASA’s 25 year old Hubble Space Telescope. It will become the biggest and most powerful space telescope ever built by humankind after it launches 30 months from now.
The flight structure for the backplane assembly truss that holds the mirrors and science instruments arrived at Goddard last August from Webb prime contractor Northrop Grumman Aerospace Systems in Redondo Beach, California.
The painstaking assembly work to piece together the 6.5 meter diameter primary mirror began just before the Thanksgiving 2015 holiday, when the first unit was successfully installed onto the central segment of the mirror holding backplane assembly.
Technicians from Goddard and Harris Corporation of Rochester, New York then methodically populated the backplane assembly one-by-one, sequentially installing the last primary mirror segment in February followed by the single secondary mirror at the top of the massive trio of mirror mount booms and the tertiary and steering mirrors inside the Aft Optics System (AOS).
Up close view shows cone shaped Aft Optics Subsystem (AOS) standing at center of Webb telescopes 18 segment primary mirror at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. ISIM science instrument module will be installed inside truss structure below. Credit: Ken Kremer/kenkremer.com
Everything proceeded according to the meticulously choreographed schedule.
“The mirror installation went exceeding well,” Durning told Universe Today.
“We have maintained our schedule the entire time for installing all 18 primary mirror segments. Then the center section, which is the cone in the center, comprising the Aft Optics System (AOS). We installed that two months ago. It went exceedingly well.”
The flight structure and backplane assembly serve as the $8.6 Billion Webb telescopes backbone.
The next step is to install the observatory’s quartet of state-of-the-art research instruments, a package known as the ISIM (Integrated Science Instrument Module), in the truss structure over the next few weeks.
“The telescope is fully integrated and we are now doing the final touches to get prepared to accept the instrument pack which will start happening later this week,” Durning explained.
The integrated optical mirror system and ISIM form Webb’s optical train.
“So we are just now creating the new integration entity called OTIS – which is a combination of the OTE (Optical Telescope Assembly) and the ISIM (Integrated Science Instrument Module) together.”
“That’s essentially the entire optical train of the observatory!” Durning stated.
“It’s the critical photon path for the system. So we will have that integrated over the next few weeks.”
The combined OTIS entity of mirrors, science module and backplane truss weighs 8786 lbs (3940 kg) and measures 28’3” (8.6m) x 8”5” (2.6 m) x 7”10“ (2.4 m).
Gold coated primary mirrors newly exposed on spacecraft structure of NASA’s James Webb Space Telescope inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms. Credit: Ken Kremer/kenkremer.com
After OTIS is fully integrated, engineers and technicians will spend the rest of the year exposing it to environmental testing, adding the thermal blanketry and testing the optical train – before shipping the huge structure to NASA’s Johnson Space Center.
“Then we will send it to NASA’s Johnson Space Center (JSC) early next year to do some cryovac testing, and the post environmental test verification of the optical system,” During elaborated.
“In the meantime Northrup Grumman is finishing the fabrication of the sunshield and finishing the integration of the spacecraft components into their pieces.”
“Then late in 2017 is when the two pieces – the OTIS configuration and the sunshield configuration – come together for the first time as a full observatory. That happens at Northrup Grumman in Redondo Beach.”
Webb’s optical train is comprised of four different mirrors. We discussed the details of the mirrors, their installation, and testing.
“There are four mirror surfaces,” Durning said.
“We have the large primary mirror of 18 segments, the secondary mirror sitting on the tripod above it, and the center section looking like a pyramid structure [AOS] contains the tertiary mirror and the fine steering mirror.”
“The AOS comes as a complete package. That got inserted down the middle [of the primary mirror].”
Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). They are made of beryllium, gold coated and about the size of a coffee table.
In space, the folded mirror structure will unfold into side by side sections and work together as one large 21.3-foot (6.5-meter) mirror, unprecedented in size and light gathering capability.
The lone rounded secondary mirror sits at the top of the tripod boom over the primary.
The tertiary mirror and fine steering mirror sit in the Aft Optics System (AOS), a cone shaped unit located at the center of the primary mirror.
“So how it works is the light from the primary mirror bounces up to the secondary, and the secondary bounces down to the tertiary,” Durning explained.
“And then the tertiary – which is within that AOS structure – bounces down to the steering mirror. And then that steering mirror steers the beams of photons to the pick off mirrors that sit below in the ISIM structure.”
“So the photons go through that AOS cone. There is a mask at the top that cuts off the path so we have a fixed shape of the beam coming through.”
“It’s the tertiary mirror that directs the photons to the fine steering mirror. The fine steering mirror then directs it [the photons] to the pick off mirrors that sit below in the ISIM structure.”
So the alignment between the AOS system and the telescopes primary and secondary mirrors is incredibly critical.
“The AOS tertiary mirror catches the light [from the secondary mirror] and directs the light to the steering mirror. The requirements for alignment were just what we needed. So that was excellent progress.”
“So the entire mirror system is checked out. The system has been integrated and the alignment has been checked.”
Webb’s golden mirror structure was tilted up for a very brief period this week on May 4 as seen in this NASA time-lapse video:
The 18-segment primary mirror of NASA’s James Webb Space Telescope was raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on May 4, 2016. Credit: NASA
The gargantuan observatory will significantly exceed the light gathering power of NASA’s Hubble Space Telescope (HST) – currently the most powerful space telescope ever sent to space.
With the mirror structure complete, the next step is ISIM science module installation.
To accomplish that, technicians carefully moved the Webb mirror structure this week into the clean room gantry structure.
As shown in this time-lapse video we created from Webbcam images, they tilted the structure vertically, flipped it around, lowered it back down horizontally and then transported it via an overhead crane into the work platform.
Time-lapse showing the uncovered 18-segment primary mirror of NASA’s James Webb Space Telescope being raised into vertical position, flipped and lowered upside down to horizontal position and then moved to processing gantry in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on May 4/5, 2016. Images: NASA Webbcam. Time-lapse by Ken Kremer/kenkremer.com/Alex Polimeni
The telescope will launch on an Ariane V booster from the Guiana Space Center in Kourou, French Guiana in 2018.
The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming. It will also study the history of our universe and the formation of our solar system as well as other solar systems and exoplanets, some of which may be capable of supporting life on planets similar to Earth.
More about ISIM in the next story.
Watch this space for my ongoing reports on JWST mirrors, science, construction and testing.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
View showing actual flight structure of mirror backplane unit for NASA’s James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.comAll 18 primary mirrors of NASA’s James Webb Space Telescope are seen fully installed on the backplane structure by technicians using a robotic arm (center) inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credit: Ken Kremer/kenkremer.comJohn Durning/Webb Telescope Deputy Project Manager, and Ken Kremer/Universe Today discuss assembly process of NASA’s James Webb Space Telescope at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credit: Ken Kremer/kenkremer.comThe James Webb Space Telescope. Image Credit: NASA/JPL
The northern constellation Auriga, showing the brightest stars of Capella, Menkalinan, and proximate Deep Sky Objects. Credit: stargazerslounge.com
Welcome back to Constellation Friday! Today, in honor of our dear friend and contributor, Tammy Plotner, we examine the Auriga constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would serve as the authoritative source of astronomy for over a thousand years to come. Since the development of modern telescopes and astronomy, this list has come to be expanded to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
One of these is the constellation of Auriga, a beautiful pentagon-shaped collection of stars that is situated just north of the celestial equator. Along with five other constellations that have stars in the Winter Hexagon asterism, Auriga is most prominent during winter evenings in the Northern Hemisphere. Auriga also belongs to the Perseus family of constellations, together with Andromeda, Cassiopeia, Cepheus, Cetus, Lacerta, Pegasus, Perseus, and Triangulum.
Mars from orbit. Valles Marineris and Volcanic region
Given it’s similarities to Earth, Mars is often referred to as “Earth’s Twin”. Like Earth, Mars is a terrestrial planet, which means it is composed largely of silicate rock and minerals that are differentiated into a core, mantle and crust. It is also located within the Sun’s “Goldilocks Zone” (aka. habitable zone), has polar ice caps, and once had flowing water on its surface. But beyond these, Mars and Earth are very different worlds.
In addition to their stark contrasts in temperature, surface conditions, and exposure to harmful radiation, Mars also takes a significantly longer time to complete a single orbit of the Sun. In fact, a year on Mars is almost twice as long as a year here on Earth – lasting 686.971 days, which works out to about 1.88 Earth years. And in the course of that orbit, the planet undergoes some rather interesting changes.
A view of Ceres in natural colour, pictured by the Dawn spacecraft in May 2015. Credit: NASA/ JPL/Planetary Society/Justin Cowart
We continue our “Definitive Guide to Terraforming” series with a look at another body in our Solar System – the dwarf planet Ceres. Like many moons in the outer Solar System, Ceres is a world of ice and rock, and is the largest body in the Asteroid Belt. Humans beings could one day call it home, but could its surface also be made “Earth-like”?
In the Solar System’s Main Asteroid Belt, there are literally millions of celestial bodies to be found. And while the majority of these range in size from tiny rocks to planetesimals, there are also a handful of bodies that contain a significant percentage of the mass of the entire Asteroid Belt. Of these, the dwarf planet Ceres is the largest, constituting of about a third of the mass of the belt and being the sixth-largest body in the inner Solar System by mass and volume.
In addition to its size, Ceres is the only body in the Asteroid Belt that has achieved hydrostatic equilibrium – a state where an object becomes rounded by the force of its own gravity. On top of all that, it is believed that this dwarf planet has an interior ocean, one which contains about one-tenth of all the water found in the Earth’s oceans. For this reason, the idea of colonizing Ceres someday has some appeal, as well as terraforming.
A bright Eta Aquarid earthgrazer streaks across the northern lights in May 2013. Credit: Bob King
The Eta Aquarid meteor shower peaks shortly before dawn on Thursday and Friday mornings. The radiant lies in Aquarius near the star Eta. Diagram: Bob King, source: Stellarium
Itching to watch a meteor shower and don’t mind getting up at an early hour? Good because this should be a great year for the annual Eta Aquarid (AY-tuh ah-QWAR-ids) shower which peaks on Thursday and Friday mornings May 5-6. While the shower is best viewed from tropical and southern latitudes, where a single observer might see between 25-40 meteors an hour, northern views won’t be too shabby. Expect to see between 10-15 per hour in the hours before dawn.
Most showers trace their parentage to a particular comet. The Perseids of August originate from dust strewn along the orbit of comet 109P/Swift-Tuttle, which drops by the inner solar system every 133 years after “wintering” for decades just beyond the orbit of Pluto.
Halley’s Comet crossing the Milky Way, taken by the Kuiper Airborne Observatory in New Zealand on April 8-9, 1986. Credit: NASA
The upcoming Eta Aquarids have the best known and arguably most famous parent of all: Halley’s Comet. Twice each year, Earth’s orbital path intersects dust and minute rock particles strewn by Halley during its cyclic 76-year journey from just beyond Uranus to within the orbit of Venus.
Our first pass through Halley’s remains happens this week, the second in late October during the Orionid meteor shower. Like bugs hitting a windshield, the grains meet their demise when they smash into the atmosphere at 147,000 mph (237,000 km/hr) and fire up for a brief moment as meteors. Most comet grains are only crumb-sized and don’t have a chance of reaching the ground as meteorites. To date, not a single meteorite has ever been positively associated with a particular shower.
A bright, earthgrazing Eta Aquarid streaks across Perseus and through the aurora on May 6, 2013. Because the radiant is low for northern hemisphere observers, earthgrazers – long, bright meteors that come up from near the horizon and have long-lasting trails. Credit: Bob King
The farther south you live, the higher the shower radiant will appear in the sky and the more meteors you’ll spot. A low radiant means less sky where meteors might be seen. But it also means visits from “earthgrazers”. These are meteors that skim or graze the atmosphere at a shallow angle and take many seconds to cross the sky. Several years back, I saw a couple Eta Aquarid earthgrazers during a very active shower. One other plus this year — no moon to trouble the view, making for ideal conditions especially if you can observe from a dark sky.
From mid-northern latitudes the radiant or point in the sky from which the meteors will appear to originate is low in the southeast before dawn. At latitude 50° north the viewing window lasts about 1 1/2 hours before the light of dawn encroaches; at 40° north, it’s a little more than 2 hours. If you live in the southern U.S. you’ll have nearly 3 hours of viewing time with the radiant 35° high.
Meteors in a meteor shower appear to radiate from a point in the distance in identical fashion to the way snow or rain radiates from a point in front of your car when you’re driving. Credit: Bob King
Grab a reclining chair, face east and kick back for an hour or so between 3 and 4:30 a.m. An added bonus this spring season will be hearing the first birdsong as the sky brightens toward the end of your viewing session. And don’t forget the sights above: a spectacular Milky Way arching across the southern sky and the planets of Mars and Saturn paired up in the southwestern sky.
Meteor shower members can appear in any part of the sky, but if you trace their paths in reverse, they’ll all point back to the radiant. Other random meteors you might see are called sporadics and not related to the Eta Aquarids. Meteor showers take on the name of the constellation from which they originate.
Aquarius is home to at least two showers. This one’s called the Eta Aquarids because it emanates from near the star Eta Aquarii. An unrelated shower, the Delta Aquarids, is active in July and early August. Don’t sweat it if weather doesn’t cooperate the next couple mornings. The shower will be active throughout the weekend, too.
Artist's concept of the prototype starshade, a giant structure designed to block the glare of stars so that future space telescopes can take pictures of planets. Credit: NASA/JPL
For countless generations, people have looked up at the stars and wondered if life exists somewhere out there, perhaps on planets much like ours. But it has only been in recent decades that we have been able to confirm the existence of extrasolar planets (aka. exoplanets) in other star systems. In fact, between 1988 and April 20th of 2016, astronomers have been able to account for the existence of 2108 planets in 1350 different star systems, including 511 multiple planetary systems.
Most of these discoveries have taken place within just the past three years, thanks to improvements in our detection methods, and the deployment of the Kepler space observatory in 2009. Looking ahead, astronomers hope to improve on these methods even further with the introduction of the Starshade, a giant space structure designed to block the glare of stars, thus making it easier to find planets – and perhaps another Earth!
