MU69: New Horizons’ Next Kuiper Belt Target Is One Big Mystery

Not as advertised? 2014 MU69 could be one big Kuiper Belt mess (NASA/JHU-APL/SwRI/Steve Gribben)

“All bound for Mu Mu Land” — The KLF, ‘Justified and Ancient’ (seems appropriate)

After visiting Pluto on July 14, 2015, NASA’s epic New Horizons mission soared into the great unknown, a.k.a. the Kuiper Belt. This strange region, which extends beyond Pluto’s orbit, is known to be populated with dwarf planets, comets, asteroids and junk that was left behind after the solar system’s formation, five billion years ago.

In an effort to better understand the solar system’s boondocks, New Horizons is on a trajectory that will create a second flyby opportunity. On New Year’s Day 2019, the spacecraft will buzz a mysterious object called 2014 MU69. But although we know this Kuiper Belt Object is out there, astronomers aren’t entirely sure what it is. And that’s a bit of a problem.

For two seconds on June 3, astronomers were presented with an opportunity to better observe MU69, but instead of clearing up its mystery the occultation event has created more questions than answers.

An occultation is when an object, like a distant asteroid, drifts in front of a background star. If astronomers time it perfectly, they can observe the star at the time of occultation in a bid to image the tiny shadow that will rapidly speed across our planet. And in the case of the June 3 event, dozens of mission team members and collaborators were ready and waiting along the predicted shadow track in South Africa and Argentina. In all, 100,000 images were taken of the star during the rapid occultation.

What they saw — or, indeed, didn’t see — is a bit of a conundrum.

“These data show that MU69 might not be as dark or as large as some expected,” said Marc Buie, a New Horizons science team member and occultation team leader from Southwest Research Institute (SwRI) in Boulder, Colo., in a statement.

Observations by the Hubble Space Telescope had previously estimated that MU69 is between 12- to 25-miles wide. That might be a pretty big overestimation by all accounts. And it may not be a single object at all.

“These results are telling us something really interesting,” said Alan Stern, New Horizons Principal Investigator also of SwRI. “The fact that we accomplished the occultation observations from every planned observing site but didn’t detect the object itself likely means that either MU69 is highly reflective and smaller than some expected, or it may be a binary or even a swarm of smaller bodies left from the time when the planets in our solar system formed.”

If it’s the latter, this could pose a problem for New Horizons.

Before the mission encountered Pluto in 2015, there was concern that the dwarf planet’s neighborhood might have been filled with debris. This concern was heightened after Pluto’s moons Styx and Kerberos were revealed by Hubble in 2011, only four years before New Horizons was set to barrel through the system. If there were more sub-resolution chunks near Pluto, they would have been regarded as collision risks.

Although New Horizons survived the Pluto encounter, if MU69 is a swarm of debris and not a solid object, mission scientists will have to assess the impact risk once again when New Horizons attempts its second flyby in 2019.

More occultations are forecast for July 10 and July 17, and NASA will also be flying its airborne observatory SOFIA through the occultation path on July 10 in hopes of better resolving MU69’s true nature.

So, as New Horizons speeds toward MU69, one of the most ancient objects in our sun’s domain, mystery and potential danger awaits.


Triton’s Ice Won’t Mix


Triton, Neptune’s largest moon, hasn’t been studied in detail since Voyager 2 did a flyby in 1989. That was until a team headed by Will Grundy, a Lowell Observatory planetary scientist, did a 10-year study into the distribution of the moon’s ices.

Soon to be published in the journal Icarus, the team has found that concentrations of nitrogen and carbon monoxide mix together and form a covering of ice on the Neptune-facing side of Triton. This is in contrast to the methane content of the atmosphere. For some reason, methane is concentrated on the non-facing Neptune hemisphere of the moon. It appears that methane doesn’t like to mix with the other volatile ices.

This is in stark contrast to the non-volatile ices, such as water and carbon dioxide. Both appear to have a homogeneous distribution, regardless of phase or geographical location.

These are incredible observations of a moon that was once a Kuiper Belt Object. However, the infrared analysis carried out on Triton could be a test-run before observations are carried out on other, more exotic, targets.

This type of long-term, detailed analysis would be equally valuable for small icy planets like Pluto, Eris, and Makemake, all of which are similar to Triton in having volatile ices like methane and nitrogen on their surfaces,” said Grundy. “We have been monitoring Pluto’s spectrum in parallel with that of Triton, but Eris and Makemake are quite a bit fainter. It is hard to get time on large telescopes to monitor them year after year. We expect that Lowell Observatory’s Discovery Channel Telescope will play a valuable role in this type of research when it comes on line.”

Source: Space Disco, Discovery Channel (yeah, I’m referencing myself), Lowell Observatory

Strangest Kuiper Belt Objects: The Top Five

From Pluto, looking at its icy moons in the Kuiper belt (NASA)

The Kuiper belt is strange. Most of this strangeness probably comes from the fact that we are only just beginning to uncover this mysterious region of the Solar System. Unlike the Oort Cloud which (possibly) lies beyond 3 × 1012 km away (over 20,000 AU, or a whopping 0.3 light years), we can actually observe the objects inside the Kuiper belt as, compared to the Oort Cloud, the Kuiper belt is on our interplanetary doorstep.

But that doesn’t mean it’s close. The Kuiper belt exists in a region of space 30–55 AU from the Sun; this is where Pluto lives (as Pluto itself is a “Kuiper belt object”, or KBO). As astronomical techniques become more advanced however, we are able to discover more KBOs in the zoo of icy-rocky bodies that live in this region.

Having just written about an oddball pair of “highly split” KBOs, I feel compelled to list my top five favourite KBOs. Here are my favourites, as some are really funny-lookin’ and others have some serious personal issues…
Continue reading “Strangest Kuiper Belt Objects: The Top Five”

Meet Antipholus and Antipholus, a Very Odd Kuiper Belt Couple

2001 QW322 is a highly split Kuiper Belt pair, orbiting eachother at a distance of 125,000 km

The highly-split Kuiper Belt pair 2001 QW322 (CFEPS)

The Kuiper Belt is an eerie, mysterious and cold region of the Solar System. In it, there are billions of small pieces of rocks with lots of fancy names. As a general designation, all objects in the Kuiper belt are called “Kuiper-belt objects” (KBO’s for short). As the Kuiper belt is located in a region just beyond Neptune, they may also be known as trans-Neptunian objects (TNO’s). Inside the Kuiper belt, we have Pluto-like objects known as “Plutoids”, classical KBO’s called “Cubewanos” (the largest being the recently discovered Makemake) and a whole host of other objects such as icy objects soon to become the next generation of periodic comets.

We are only scraping the surface, finding only a small portion of KBOs. We know of a thousand, but astronomers believe there may be as many as 70,000 measuring over 100km in diameter, plus countless other smaller objects.

Therefore, it is not very surprising that some rather strange KBOs exist, and possibly the oddest one has just been observed. From the same team that discovered KBO 2008 KV42 — a piece of rock orbiting the wrong way in a one-way Solar System — a binary Kuiper belt object has been found with a huge orbit…
Continue reading “Meet Antipholus and Antipholus, a Very Odd Kuiper Belt Couple”