With the government shutdown, news out of NASA is sometimes sparse. But thankfully amateur astronomers can fill in some of the holes! While Juno’s project manager Rick Nybakken has confirmed that the spacecraft successfully completed its slingshot flyby of Earth yesterday, images taken by amateur astronomers around the world also conclusively confirm that Juno is now “bang on target!” tweeted Nick Howes of the Remanzacco Observatory team. This image from Howes, Ernesto Guido and Martino Nicolini shows the path of Juno across the sky, as seen from a remote telescope in Spain. “The spacecraft is trailed in the image due to its fast speed,” the team wrote on their website, and extrapolations of Juno’s orbit shows it is heading straight for Jupiter.
Meanwhile, there are some concerns about the spacecraft going into safe mode immediately after the flyby. Our previous article by Ken Kremer reported that the mission teams are assessing the situation, and that the spacecraft is “power positive.”
One idea of why the spacecraft went into safe mode is that the battery was being depleted faster than anticipated, but the team is still working to confirm the reason.
Closest approach was at 12:21 PM PST (19:21 UTC, 3:21 PM EDT).
For more information about the flyby, check out this new video from Bill Nye the Science Guy — who has a new video series called “Why With Nye.”
Every so often, engineers send a spacecraft in Earth’s general direction to pick up a speed boost before heading elsewhere. But sometimes, something strange happens — the spacecraft’s speed varies in an unexpected way. Even stranger, this variation happens only during some Earth flybys.
“We detected the flyby anomaly during Rosetta’s first Earth visit in March 2005,” stated Trevor Morley, a flight dynamics specialist at the European Space Agency’s European Space Operations Centre in Darmstadt, Germany.
“Frustratingly, no anomaly was seen during Rosetta’s subsequent Earth flybys in 2007 and 2011. This is a real cosmic mystery that no one has yet figured out.”
The phenomenon has been noticed in several spacecraft (both from ESA and NASA) since 1990. NASA’s NEAR asteroid spacecraft in January 1998 had the largest change, of 13 millimeters (0.5 inches) a second. The smallest variations, with NASA’s Saturn-bound Cassini in 1999 and Mercury-pointing MESSENGER in 2005, were below the threshold of measurement.
ESA won’t even speculate on what’s going on. “The experts are stumped,” the agency says in a press release.
Those experts, however, do have some ideas on how to track that down. ESOC plans to watch Juno’s flyby using a 35 meter deep-space dish in Malargüe, Argentina, as well as a 15-meter dish in Perth, Australia
“The stations will record highly precise radio-signal information that will indicate whether Juno speeds up or slows down more or less than predicted by current theories,” ESA states.
What do you think is going on? Let us know in the comments!
Just as anticipated, on Friday, Feb. 15, asteroid 2012 DA14 passed us by, zipping 27,000 kilometers (17,000 miles) above Earth’s surface — well within the ring of geostationary weather and communications satellites that ring our world. Traveling a breakneck 28,100 km/hr (that’s nearly five miles a second!) the 50-meter space rock was a fast-moving target for professional and amateur observers alike. And even as it was heading away from Earth DA14 was captured on camera by a team led by MIT researcher Dr. Nicholas Moskovitz using the 2.1-meter telescope at the Kitt Peak National Observatory in Tucson, AZ. The team’s images are shown above as an animated gif (you may need to click the image to play it.)
This object’s close pass, coupled with the completely unexpected appearance of a remarkably large meteor in the skies over Chelyabinsk, Russia on the morning of the same day, highlight the need for continued research of near-Earth objects (NEOs) — since there are plenty more out there where these came from.
“Flybys like this, particularly for objects smaller than 2012 DA14, are not uncommon. This one was special because we knew about it well in advance so that observations could be planned to look at how asteroids are effected by the Earth’s gravity when they come so close.”
– Dr. Nicholas Moskovitz, MIT
The animation shows 2012 DA14 passing inside the Little Dipper, crossing an area about a third the size of the full Moon in 45 minutes. North is to the left.
(For a high-resolution version of the animation, click here.)
According to the National Optical Astronomy Observatory, which operates the Kitt Peak Observatory, Dr. Moskovitz’ NSF-supported team “are analyzing their data to measure any changes in the rotation rate of the asteroid after its close encounter with the Earth. Although asteroids are generally too small to resolve with optical telescopes, their irregular shape causes their brightness to change as they rotate. Measuring the rotation rate of the asteroid in this way allows the team to test models that predict how the earth’s gravity can affect close-passing asteroids. This will lead to a better understanding of whether objects like 2012 DA14 are rubble piles or single solid rocks.
“This is critical to understanding the potential hazards that other asteroids could pose if they collide with the Earth.”
So just how close was DA14’s “close pass?” Well, if Earth were just a few minutes farther along in its orbit, we would likely be looking at images of its impact rather than its departure.*
Although this particular asteroid isn’t expected to approach Earth so closely at any time in the foreseeable future — at least within the next 130 years — there are lots of such Earth-crossing objects within the inner Solar System… some we’re aware of, but many that we’re not. Identifying them and knowing as many details as possible about their orbits, shapes, and compositions is key.
Even this soon after the Feb. 15 flyby observations of 2012 DA14 have provided more information on its orbit and characteristics., allowing for fine-tuning of the data on it.
According to the Goldstone Radar Observatory web page, the details on 2012 DA14 are as follows:
Semimajor axis 1.002 AU
Inclination 10.4 deg
Perihelion distance 0.893 AU
Aphelion distance 1.110 AU
Absolute magnitude (H) 24.4
Diameter ~50 meters (+- a factor of two)
Rotation period ~6 h (N. Moskovitz, pers. comm.)
Pole direction unknown
Lightcurve amplitude ~1 mag (N. Moskovitz, pers. comm.)
Spectral class Ld (N. Moskovitz, pers. comm.)
Goldstone is currently conducting radar observations on the asteroid. A radar map of its surface and motion is anticipated in the near future.
Also, in an encouraging move by international leaders in the field, during the fiftieth session of the Scientific and Technical Subcommittee of the Committee on the Peaceful Uses of Outer Space, currently being held from at the United Nation Office in Vienna, near-Earth objects are on the agenda with a final report to be issued by an Action Team. Read the report PDF here.
*According to astronomer Phil Plait, while the orbits of Earth and DA14 might intersect at some point, on the 15th of February 2013 the asteroid slipped just outside of Earth’s orbit — a little over 17,000 miles shy. “It was traveling one way and the Earth another, so they could not have hit each other on this pass no matter where Earth was in its orbit,” he wrote in an email. Still, 17,000 miles is a very close call astronomically, and according to Neil deGrasse Tyson on Twitter, it “will one day hit us, like the one in Russian [sic] last night.” When? We don’t know yet. That’s why we must keep watching.
Asteroid 2012-DA14 will pass Earth closely on Feb. 15, 2013 (NASA)
On February 15 a chunk of rock about 50 meters wide will whiz by Earth at nearly 8 km/s, coming within 27,680 km of our planet’s surface — closer than many weather and communications satellites.
For those of you more comfortable with imperial units, that’s 165 feet wide traveling 17,800 mph coming within 17,200 miles. But regardless whether you prefer meters or miles, in astronomy that’s what’s called a close call.
Scientists stress that there’s no danger of an impact by this incoming asteroid, designated 2012-DA14, but it’s yet another reminder that in our neck of the Solar System we are definitely not alone.
“2012-DA14 will definitely not hit Earth,” says JPL’s near-Earth object specialist Don Yeomans. “The orbit of the asteroid is known well enough to rule out an impact.”
But with 2012-DA14’s upcoming February flyby Yeomans notes, “this is a record-setting close approach.”
The rocky asteroid will come within about 4 Earth radii, which is well within the orbits of geosynchronous satellites. During its closest approach at 19:26 UTC it should be visible in the sky to amateur telescopes (but not the naked eye), becoming as bright as an 7th- or 8th-magnitude star.
Radar observatories will be watching 2012-DA14 during the days leading up to and following its approach in an attempt to better determine its size, shape and trajectory. NASA’s Goldstone facility will have an eye — er, dish — on DA14, but it won’t be visible to Arecibo. Stay tuned for more info!
Read more about 2012-DA14 on the JPL Near-Earth Object Program page here.
Color-composite raw image of Titan’s southern hemisphere. Note the growing south polar vortex. (NASA/JPL/SSI/Jason Major)
Last Thursday, November 29, Cassini sailed past Titan for yet another close encounter, coming within 1,014 kilometers (603 miles) of the cloud-covered moon in order to investigate its thick, complex atmosphere. Cassini’s Visible and Infrared Mapping Spectrometer (VIMS), Composite Infrared Spectrometer (CIRS) and Imaging Science Subsystems (ISS) instruments were all busy acquiring data on Titan’s atmosphere and surface… here are a couple of color-composites made from raw images captured in visible light channels as well as some of the more interesting monochrome raw images. Enjoy!
The structure of Titan’s upper-level hazes, which extend ten times the height of Earth’s atmosphere. (NASA/JPL/SSI)
Cassini captured this view of Titan’s crescent during its approach, from a distance of 193,460 kilometers (NASA/JPL/SSI/Jason Major)
Cassini’s continuum filter (CB3) allows it to image Titan’s surface. The dark areas are vast fields of hydrocarbon sand dunes (NASA/JPL/SSI)
These images have not been validated or calibrated by NASA or the mission team.
Here’s a quick look at one of my favorite cosmic photo subjects – the varying layers of atmosphere that enshroud Saturn’s enormous moon Titan. The image above is a color-composite made from three raw images acquired by Cassini during its latest flyby.
On June 7 Cassini approached Titan within 596 miles (959 km) and imaged portions of the moon’s northwest quadrant with its radar instrument, as well as conducted further investigations of areas near the equator where surface changes were detected in 2010.
The image here was assembled from three raw images captured in red, green and blue visible light channels. It reveals some structure in the upper hydrocarbon haze layers that extend upwards above the moon’s opaque orange clouds — reaching 400-500 km in altitude, Titan’s atmosphere is ten times thicker than Earth’s!
The June 6 flyby was the second in a series of passes that will take Cassini into a more inclined orbit, where it will reside for the next three years as it investigates Saturn’s polar regions and obtains better views of its ring system.
While many of us here on Earth were waiting for the Moon to take a bite out of the Sun this past Sunday, Cassini was doing some moon watching of its own, 828.5 million miles away!
The image above is a color-composite raw image of Methone (pronounced meh-tho-nee), a tiny, egg-shaped moon only 2 miles (3 km) across. Discovered by Cassini in 2004, Methone’s orbit lies between Mimas and Enceladus, at a distance of 120,546 miles (194,000 km) from Saturn — that’s about half the distance between Earth and the Moon.
At an altitude of 1,200 miles (1900 km) this was Cassini’s closest pass ever of Methone, a rare visit that occurred after the spacecraft departed the much larger Tethys.
Along with sister moons Pallene and Anthe, Methone is part of a group called the Alkyonides, named after daughters of the god Alkyoneus in Greek mythology. The three moons may be leftovers from a larger swarm of bodies that entered into orbit around Saturn — or they may be pieces that broke off from either Mimas or Enceladus.
Earlier on Sunday, May 20, Cassini paid a relatively close visit to Tethys (pronounced tee-this), a 662-mile (1065-km) -wide moon made almost entirely of ice. One of the most extensively cratered worlds in the Solar System, Tethys’ surface is dominated by craters of all sizes — from the tiniest to the giant 250-mile (400-km) -wide Odysseus crater — as well as gouged by the enormous Ithaca Chasma, a series of deep valleys running nearly form pole to pole.
Cassini passed within 34,000 miles (54,000 km) of Tethys on May 20, before heading to Methone and then moving on to its new path toward Titan, a trajectory that will eventually take it up out of Saturn’s equatorial plane into a more inclined orbit in order to better image details of the rings and Saturn’s poles.
Read more about this flyby on the Cassini mission site here. and see more raw images straight from the spacecraft on the CICLOPS imaging lab site here.
Image credit: NASA / JPL / Space Science Institute. (Color-composite image edited by J. Major.)
After completing its most recent flyby of Enceladus, Cassini made a pass by Dione — its final visit of the icy moon for the next three years. Coming within 5,000 miles (8000 km) of Dione on May 2, Cassini captured some fantastic images of the moon’s heavily-cratered and frozen surface. Here’s just a few of the raw images that arrived back here on Earth earlier today:
698 miles (1123 km) in diameter, Dione orbits Saturn at about the same distance that the Moon orbits Earth. Its composition is two-thirds water ice, which at the incredibly cold temperatures found around Saturn behaves like rock does here on Earth.
Cassini won’t visit Dione so closely again until June 2015, after spending three years angled high out of the equatorial plane while it studies Saturn’s rings and polar regions.
As Carolyn Porco, Cassini Imaging Team Leader said today, “This is exploration at its finest. It won’t continue forever. So, enjoy it while it lasts!”
See more on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site here.
The latest images are in from Saturn’s very own personal paparazzi, NASA’s Cassini spacecraft, fresh from its early morning flyby of the ice-spewing moon Enceladus. And, being its last closeup for the next three years, the little moon didn’t disappoint!
The image above is a composite I made from two raw images (this one and this one) assembled to show Enceladus in its crescent-lit entirety with jets in full force. The images were rotated to orient the moon’s southern pole — where the jets originate — toward the bottom.
Cassini was between 72,090 miles (116,000 km) and 90,000 miles (140,000 km) from Enceladus when these images were acquired.
This morning’s E-19 flyby completed a trio of recent close passes by Cassini of the 318-mile (511-km) -wide moon, bringing the spacecraft as low as 46 miles (74 km) above its frozen surface. The goal of the maneuver was to gather data about Enceladus’ internal mass — particularly in the region around its southern pole, where a reservoir of liquid water is thought to reside — and also to look for “hot spots” on its surface that would give more information about its overall energy distribution.
Cassini had previously discovered that Enceladus radiates a surprising amount of heat from its surface, mostly along the “tiger stripe” features — long, deep furrows (sulcae) that gouge its southern hemisphere, they are the source of the water-ice geysers.
Cassini also used the flyby opportunity to study Enceladus’ gravitational field.
By imaging the moon with backlit lighting from the Sun the highly-reflective ice particles in the jets become visible. More direct lighting reduces the jets’ visibility in images, which must be exposed for the natural light of the scene or risk “blowing out” due to Enceladus’ natural high reflectivity.
The images below are raw spacecraft downloads right from the Cassini’s imaging headquarters in Boulder, CO.
Cassini also swung closely by Dione during this morning’s flyby but the images from that encounter aren’t available yet. Stay tuned to Universe Today for more postcards from Saturn!
As always, you can follow along with the ongoing Cassini mission on JPL’s dedicated site here, as well as on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site.
Spray it again, Enceladus! This Saturday the Cassini spacecraft paid another visit to Enceladus, Saturn’s 318-mile-wide moon that’s become famous for its icy geysers.During its latest close pass Cassini got a chance to “taste” Enceladus’ spray using its ion and neutral mass spectrometer, giving researchers more information on what sort of watery environment may be hiding under its frozen, wrinkled surface.
The image above shows a diagonal view of Enceladus as seen from the night side. (The moon’s south pole is aimed at a 45-degree angle to the upper right.) Only by imaging the moon backlit by the Sun can the geysers of fine, icy particles be so well seen.
During the flyby Cassini passed within 46 miles (74 km) of Enceladus’ surface.
This image was captured during the closest approach, revealing the distressed terrain of Enceladus’ south pole. Although a bit blurry due to the motion of the spacecraft, boulders can be made out resting along the tops of high , frozen ridges. (Edited from the original raw image to enhance detail.)
This flyby occurred less than three weeks after Cassini’s previous visit to Enceladus. Why pay so much attention to one little moon?
Basically, it’s the one place in our solar system that we know of where a world is spraying its “habitable zone” out into space for us to sample.
“More than 90 jets of all sizes near Enceladus’s south pole are spraying water vapor, icy particles, and organic compounds all over the place,” said Carolyn Porco, planetary scientist and Cassini Imaging science team leader, during a NASA interview in March. “Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth’s oceans.
“In the end, it’s the most promising place I know of for an astrobiology search,” said Porco. (Read the full interview here.)
Not to be left out, Tethys was also paid a visit by Cassini. The 662-mile-wide moon boasts one of the most extensively cratered surfaces in the Solar System, tied with its sister moons Rhea and Dione. In this raw image captured by Cassini on April 14, we can see some of the moon’s ancient, larger craters, including Melanthius with its enormous central peak.
Cassini passed Tethys at a distance of about 6,000 miles (9000 km) after departing Enceladus. Cassini’s composite infrared spectrometer looked for patterns in Tethys’ thermal signature while other instruments studied the moon’s geology.
Image credits: NASA/JPL/Space Science Institute. See more images from the Cassini mission on the CICLOPS site here.