from the taking-a-closer-look dept.
NASA's New Horizons team will again attempt observations of a stellar occultation of 2014 MU69, provisionally nicknamed Ultima Thule. Previous observations made when the object passed in front of a background star suggested that it was a contact binary and may have a small moon:
The goal is to learn as much as possible about 2014 MU69, nicknamed Ultima Thule, which New Horizons will zoom past on Jan. 1, 2019. "This occultation will give us hints about what to expect at Ultima Thule and help us refine our flyby plans," New Horizons occultation-event leader Marc Buie, of the Southwest Research Institute in Boulder, Colorado, said in a statement.
This is not the mission team's first shadow rodeo. Last summer, scientists traveled to Argentina and South Africa for occultation observations; the Argentina crew hit the jackpot, gathering data that helped set the planned flyby distance at 2,175 miles (3,500 kilometers).
[...] Ultima Thule lies about 1 billion miles (1.6 billion km) beyond Pluto, which New Horizons famously flew by in July 2015. Scientists think Ultima Thule is about 20 miles (32 km) across if it's a single object; if it's two bodies, each component is probably 9 miles to 12 miles (15 to 21 km) long.
NASA's New Horizons spacecraft changed our view of the outer solar system forever when it flew by Pluto in 2015. Now, it's on its way to the next destination: a Kuiper Belt object (KBO) known only as 2014 MU69. Although the spacecraft won't reach its target until New Year's Day in 2019, NASA is already looking ahead to learn as much about 2014 MU69 as possible, thanks to a convenient temporary alignment that recently allowed the object to pass in front of a background star.
[...] "This effort, spanning six months, three spacecraft, 24 portable ground-based telescopes, and NASA's SOFIA airborne observatory was the most challenging stellar occultation in the history of astronomy, but we did it!" said Alan Stern, the New Horizons mission principal investigator, in a press release. "We spied the shape and size of 2014 MU69 for the first time, a Kuiper Belt scientific treasure we will explore just over 17 months from now. Thanks to this success we can now plan the upcoming flyby with much more confidence."
The physical characteristics of 2014 MU69 are still unclear. It is estimated to have a diameter between 18 and 41 km, but may be composed of multiple objects.
2014 MU69, which New Horizons will fly by on January 1, 2019, appears to have an elongated shape or may be comprised of two objects:
Based on the occultation data, 2014 MU69 definitely appears to have an odd shape. In a press release, NASA officials said that it's either football shaped or a type of object called a contact binary. The size of MU69 or its components also can be determined from these data. It appears to be no more than 20 miles (30 km) long, or, if a binary, each about 9-12 miles (15-20 km) in diameter.
By comparison, Comet 67P/Churyumov–Gerasimenko consists of a large lobe measuring about 4.1 × 3.3 × 1.8 km and a small lobe of about 2.6 × 2.3 × 1.8 km.
It's not just Saturn and gas giants such as Uranus which have rings in our solar system – as a tiny dwarf planet has just been spotted with its very own.
It's the first dwarf planet beyond Neptune to be spotted with its own ring – and could prove that such rings are not uncommon in the outer solar system.
takyon: Haumea has two known moons as well as this newly discovered ring:
A stellar occultation observed on 21 January 2017 indicated the possibility of a ring system around Haumea. As published in Nature on 11 October 2017, this occultation was confirmed to be a ring, representing the first such ring discovered for a TNO. The ring has a radius of about 2,287 km, a width of ~70 km and an opacity of 0.5. The ring plane coincides with Haumea's equator and the orbit of its larger, outer moon Hi'iaka. The ring is close to the 3:1 resonance with Haumea's rotation.
Haumea is known for its extremely elongated shape, a consequence of its rapid rotation.
The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation (DOI: 10.1038/nature24051) (DX)
The object, known as 2014 MU69, is small, no more than 20 miles wide [30-40 km], but planetary scientists hope that it will turn out to be an ancient and pristine fragment from the earliest days of the solar system.
The moon, if it exists, might be about three miles [~5 km] wide, circling at a distance of about 120 miles [~190 km] from MU69, completing an orbit every two to four weeks, estimated Marc W. Buie, an astronomer at the Southwest Research Institute in Boulder, Colo.
He cautioned that the findings were tentative. "The story could change next week," he said.
Dr. Buie and others working on NASA's New Horizons mission provided an update on Tuesday at a meeting of the American Geophysical Union meeting here.
New Horizons is set to fly closer to 2014 MU69 than it did to Pluto (~3,500 km vs. 12,472 km). Flyby or collision course?
Nissan unveiled its Navara Dark Sky concept vehicle at the Hannover Motor Show this week, and it's a vehicle designed for astronomers. The truck is an enhanced version of the automaker's Navara vehicle and along with including some handy new features, it also has a trailer in tow that carries a powerful PlaneWave telescope. Designed with the European Space Agency, the trailer not only houses the telescope but has a number of features that protect the telescope and help researchers collect and transmit data.
The trailer boasts a refrigerated interior that helps stabilize the telescope and battery packs can power a WiFi hotspot, a laptop station and a UHF transmitter for data relay. Further, the truck itself makes use of red lighting in order to cut down on light pollution while the ProPilot driver assistance technology takes the trailer into account and helps locate parking that best accommodates the trailer and telescope.
Seems like a good platform for measuring occultations.
Also at Autoblog.
The New Horizons team is preparing for their spacecraft to fly by 2014 MU69 (nicknamed Ultima Thule) on Jan. 1, 2019. At the current planned flyby distance, the spacecraft's instruments will take higher resolution imagery of the object(s) than what was seen at Pluto:
Because Ultima is small — probably just 25 km (16 miles) or so in diameter — it will remain just a point of light to New Horizons until about 2 days before the close flyby. However, in the final hours around closest approach, New Horizons will be able to map Ultima at higher resolutions than we achieved at Pluto, because we will fly by Ultima at a much closer range than we did at Pluto
We will obtain geologic mapping resolutions as high as 35 meters (110 feet) per pixel using LORRI. By comparison, our highest resolution Pluto mapping was about 80 meters (260 feet) per pixel.
With the Ralph imager, we also plan to acquire color images of Ultima with resolutions as high as 330 meters (0.2 miles) per pixel, and composition mapping at a resolution of 1.8 km (1.1 miles) per pixel. Stereo imaging made on approach will map the surface topography of Ultima at about 80 meters (260 feet) per pixel.The first detailed imagery of Ultima will be downlinked to Earth once the spacecraft has completed its main flyby objectives late on January 1st, and will be released to the public after processing and image analysis on January 2nd. More images, as well as spectra and other data sets, will be downlinked on January 2nd, 3rd, and 4th — so get ready to learn a lot about Ultima in the first week of the new year! Then the spacecraft will slip behind the Sun as seen from Earth and image transmissions will cease for 5 days until the spacecraft reappears and can resume data transmissions.
The total data volume collected on the Ultima flyby will be close to 50 gigabits. Because New Horizons is so far from Earth, about 6 billion km (4 billion miles), its data transmission speed is now only about 1,000 bits per second. This limitation, and the fact that we share NASA's Deep Space Network of tracking and communication antennas with over a dozen other NASA missions, means that it will take 20 months or more, until late in 2020, to send all of the data about Ultima and its environment back to Earth.
The team has until Dec. 16 to determine if there are any hazards (such as dust or satellites) that will necessitate changing the closest approach distance from 3,500 km to 10,000 km.
[According to the Deep Space Networkpage, at the time of this writing, the New Horizons probe is at a distance of 6.56 billion km with a round-trip light time of 12.16 hours. We're gonna need some faster light! --Ed.]
On Monday night, for a few areas of South and Central America, as well as the Caribbean, Sirius will probably briefly disappear. This will occur as a small asteroid passes in front of the star, occulting it for up to 1.6 seconds, according to the International Occultation Timing Association. (Yes, the acronym is IOTA).
In this case, the asteroid 4388 Jürgenstock will have an apparent diameter just an iota bigger than Sirius. The angular diameter of the asteroid is about 0.007 arcseconds (an arcsecond is 1/3,600th of a degree of the night sky), whereas the angular diameter of Sirius is 0.006 arcseconds. Thus, as the asteroid passes in front of Sirius, the star will briefly dim, perhaps completely, before quickly brightening again. Sirius may appear to blink once, slowly.
[...] With a diameter of 4.7km, this inner-asteroid belt object was discovered in 1964 by an astronomer named—you guessed it—Jürgen Stock. This occultation should allow astronomers a rare opportunity to better characterize the dimensions of the asteroid. It is likely to have an irregular shape—further contributing to the uncertainty about the extent to which it will block the light from Sirius.