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Space News Update — June 9, 2020 —

Contents

In the News

Story 1:

Finally! Mars InSight’s Mole is Now Underground

Story 2:

Two New Beasts for an Explosive Zoo

Story 3:

The Detective Aboard NASA's Perseverance Rover

Departments

The Night Sky

ISS Sighting Opportunities

NASA-TV Highlights

Space Calendar

Food for Thought

Space Image of the Week

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1. Finally! Mars InSight’s Mole is Now Underground

NASA's InSight Mars lander acquired this image using its robotic arm-mounted, Instrument Deployment Camera (IDC).

This image was acquired on June 3, 2020, Sol 540. Note the scoop pushing the mole is now flush with the ground.

Image Credit: NASA/JPL-Caltech

It looks like the InSight Lander’s Mole instrument is making some progress. After months of perseverance, the

team operating the instrument has succeeded in getting the Mole at least some distance into the ground.

That’s a victory in itself, considering all the setbacks there’ve been. But it’s too soon to celebrate: there’s quite

a ways to go before the Mole can deliver any science.

The Mole is the comfortable name for the Heat Flow and Physical Properties Package, or HP3. Its job is to

penetrate into the Martian soil, to a depth of 5m (16 ft.) The idea is to place the Mole’s series of embedded

heat sensors into the soil and measure the heat coming from the interior of Mars. The Mole will measure the

increase of temperature with depth, called the geothermal gradient, and thermal conductivity. Multiplying

those two values give the heat flow.

By studying the thermal processes in the interior of the planet, scientists can learn a lot about the history of

Mars, and how it formed. They may also gain insights into how other rocky bodies formed.

The Mole was designed and built by the German Aerospace Center, or DLR, as their contribution to the InSight

mission. It can gather some useful scientific data from a shallower depth than its maximum of 5 m. At about

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3m, it’s deep enough that seasonal changes won’t affect the data. But as of now, it’s nowhere near deep

enough.

In May NASA announced that they were using the scoop on the end of InSight’s robotic arm to exert

downward pressure on the Mole. That was risky, since the Mole’s wiring harness is on the top, where the

scoop needed to exert pressure. Damage the harness, and that could spell the end.

But NASA and DLR personnel were between a rock and a hard place. A type of compacted soil called duracrust

was preventing the hammering action of the Mole from penetrating the soil. They were running out of things

to try.

Now NASA has tweeted that the Mole is underground, which represents progress.

After several assists from my robotic arm, the mole appears to be underground. It’s been a real

challenge troubleshooting from millions of miles away. We still need to see if the mole can dig on its

own. More from our @DLR_en partners: https://t.co/7YjJIF6Asx #SaveTheMole

pic.twitter.com/qHtaypoxPp

— NASA InSight (@NASAInSight) June 3, 2020

Using the instrument arm scoop to get the Mole into the ground is a victory of sorts, but the method has

limitations. Once it’s buried, the arm scoop can no longer apply any downward force to the submerged

instrument. Now the Mole has to resume the hammering motion that it uses to work its way into the ground.

This is schematic of the

estimated temperature profile

of Earth. On Earth, the heat

has several causes, including

the decay of naturally

radioactive elements. The

Mole’s job is to begin to piece

together a similar profile for

Mars. Image Credit: By Bkilli1

– Own work, CC BY-SA 3.0,

https://commons.wikimedia.or

g/w/index.php?curid=2893430

8

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Will it work?

Mission personnel saw this moment coming back in May, when they took the calculated risk of pressing down

on the Mole with the instrument arm scoop. They knew that if that worked, it would not be a complete

solution. They could use the method to get the Mole started, but now it’s up to the instrument’s self-

hammering motion to drive the Mole deeper.

The Mole relies on friction between itself and the soil to drive itself into the ground. The duracrust prevented

that from happening, because it was too solid to fall into the Mole’s hole, filling it and providing the necessary

friction. If the Mole is now deeper than the problematic duracrust, there might be enough friction for the Mole

to continue downward.

So even though this latest announcement represents some progress, the future is still uncertain.

Source: Universe Today Return to Contents

This is an image from the DLR’s

test bed, where they’re trying to

solve the Mole’s problem. One of

the complications is that the Mole

is not at 90 degrees right now.

The instrument arm scoop can

only contact the Mole in one tiny

spot, and in between each

placement and self-hammering

action, it has to be carefully

repositioned. The placement of

the Mole and the limited reach of

the arm compounds the problem.

Image Credit: DLR

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2. Two New Beasts for an Explosive Zoo

Artist’s illustration comparing FBOTs to normal supernovae and gamma-ray bursts.

Bill Saxton / NRAO / AUI / NSF

And that makes three: Astronomers are beginning to understand what may be causing a special kind of flare in the

distant universe. And you thought gamma-ray bursts were spectacular!

Well, they are: Those titanic stellar explosions vastly outshine complete galaxies and shoot out tenuous jets at near-

light speed. But a new class of objects, known as Fast Blue Optical Transients (FBOTs) for their rapid flares and

blue-hot color, compare to gamma-ray bursts as dinosaurs compare to jaguars. The jets they produce are slower,

shooting out at about half the speed of light. But they can also be 10,000 times more massive, carrying up to 10%

of the Sun’s mass.

Introducing the Menagerie

Radio observations revealed these properties in one explosion known as CSS161010, which occurred in a dwarf

galaxy some 500 million light-years away in the constellation Eridanus. Brightening and fading in just a few days,

the burst was discovered on October 10, 2016, by the automated Catalina Sky Survey and, independently, by the All

Sky Automated Supernova Survey (ASAS-SN). Deanne Coppejans (Northwestern) and colleagues carried out follow-

up studies of the blast with the Very Large Array in New Mexico, the GMRT radio telescope in Mexico, and NASA’s

Chandra X-ray Observatory, publishing the results in Astrophysical Journal Letters.

CSS161010 resembles another stellar explosion, discovered by the ATLAS survey on June 16, 2018, 200 million

light-years away in Hercules. Researchers presented observations in early 2019 of this weird, extreme supernova,

officially known as AT2018cow but quickly nicknamed “The Cow.” In the case of CSS161010, however, “it took

almost two years to figure out what we were looking at just because it was so unusual,” according to coauthor

Raffaella Margutti (also at Northwestern).

Meanwhile, the Zwicky Transient Facility at Palomar Mountain (California) had bagged another luminous burst. That

brings the total number of extremely energetic FBOTs to three. Officially the event is ZTF18abvkwla, but

astronomers soon nicknamed it “The Koala.” (Soon there may be a whole zoo!) ZTF's telescope recorded the event

on September 12, 2018, in a dwarf galaxy 3.4 billion light-years away in the constellation Aries, the Ram.

Again, follow-up radio and X-ray observations, this time by Anna Ho (Caltech) and colleagues, revealed the

explosion to be much more powerful than normal supernovae, rivaling gamma-ray bursts in energy. In their paper,

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Ho and her colleagues conclude that FBOTs are “at least two to three orders of magnitude less common” than core-

collapse supernovae.

An artist's illustration of a fast blue optical transient (FBOT). Bill Saxton / NRAO / AUI / NSF

A New Kind of Supernova?

So what are these “new beasts,” as Margutti calls them? Most astronomers believe they are indeed massive stellar

explosions, like gamma-ray bursts, leaving neutron stars or black holes in their wake. But in the case of FBOTs,

thick, dense clouds of material surround the exploding stars, possibly formed as the result of interaction with a

binary companion. Another technical difference is that FBOT spectra contain signatures of hydrogen and helium.

Gamma-ray burst spectra do not, probably because the progenitor star completely lost its hydrogen-rich outer

envelope at an earlier stage.

Still, there may be a connection. Ralph Wijers (University of Amsterdam), who was not involved in the new studies,

believes there could be a continuum between regular supernova explosions and the most energetic gamma-ray

bursts. “It looks like these FBOTs, with associated radio and X-ray emissions that indicate mild relativistic outflows,

might well fill in part of the gap,” he says.

Yet another clue to FBOTs’ true nature may be found in their host galaxies. In all three cases mentioned here, Keck

Telescope spectra revealed that the blasts occurred in puny galaxies with a high star formation rate. The low

abundance of elements heavier than hydrogen or helium in dwarf galaxies may have influenced stellar evolution in

some uncommon way, enabling these rare explosions. Alternatively, FBOTs may represent so-called tidal disruption

events, where unlucky stars are ripped apart and consumed whole by intermediate-mass black holes.

Source: Sky and Telescope Return to Contents

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3. The Detective Aboard NASA's Perseverance Rover

As seen in this artist's concept, the SHERLOC instrument is located on the end of the robotic arm of NASA's

Perseverance Mars rover. Credits: NASA/JPL-Caltech

Mars is a long way from 221B Baker Street, but one of fiction's best-known detectives will be represented on

the Red Planet after NASA's Perseverance rover touches down on Feb. 18, 2021. SHERLOC, an instrument on

the end of the rover's robotic arm, will hunt for sand-grain-sized clues in Martian rocks while working in

tandem with WATSON, a camera that will take close-up pictures of rock textures. Together, they will study

rock surfaces, mapping out the presence of certain minerals and organic molecules, which are the carbon-

based building blocks of life on Earth.

SHERLOC was built at NASA's Jet Propulsion Laboratory in Southern California, which leads the Perseverance

mission; WATSON was built at Malin Space Science Systems in San Diego. For the most promising rocks, the

Perseverance team will command the rover to take half-inch-wide core samples, store and seal them in metal

tubes, and deposit them on the surface of Mars so that a future mission can return them to Earth for more

detailed study.

SHERLOC will be working with six other instruments aboard Perseverance to give us a clearer understanding of

Mars. It's even helping the effort to create spacesuits that will hold up in the Martian environment when

humans set foot on the Red Planet. Here's a closer look.

The Power of Raman

SHERLOC's full name is a mouthful: Scanning Habitable Environments with Raman & Luminescence for

Organics & Chemicals. "Raman" refers to Raman spectroscopy, a scientific technique named after the Indian

physicist C.V. Raman, who discovered the light-scattering effect in the 1920s.

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"While traveling by ship, he was trying to discover why the color of the sea was blue," said Luther Beegle of

JPL, SHERLOC's principal investigator. "He realized if you shine a light beam on a surface, it can change the

wavelength of scattered light depending on the materials in that surface.”

This effect is called Raman scattering. Scientists can identify different molecules based on the distinctive

spectral "fingerprint" visible in their emitted light. An ultraviolet laser that is part of SHERLOC will allow the

team to classify organics and minerals present in a rock and understand the environment in which the rock

formed. Salty water, for example, can result in the formation of different minerals than fresh water. The team

will also be looking for astrobiology clues in the form of organic molecules, which among other things, serve as

potential biosignatures, demonstrating the presence life in Mars' ancient past.

An engineering model of SHERLOC, one the instruments onboard NASA's Perseverance Mars rover. Located on the end of

the rover's robotic arm, SHERLOC will help determine which samples to take so that they can be sealed in metal tubes

and left on the Martian surface for future return to Earth. Credits: NASA/JPL-Caltech

"Life is clumpy," Beegle said. "If we see organics clumping together on one part of a rock, it might be a sign

that microbes thrived there in the past."

Nonbiological processes can also form organics, so detecting the compounds isn't a sure sign that life formed

on Mars. But organics are crucial to understanding whether the ancient environment could have supported life.

A Martian Magnifying Glass

When Beegle and his team spot an interesting rock, they'll scan a quarter-sized area of it with SHERLOC's laser

to tease out the mineral composition and whether organic compounds are present. Then WATSON (Wide

Angle Topographic Sensor for Operations and eNgineering) will take close-up images of the sample. It can

snap images of Perseverance, too, just as NASA's Curiosity rover uses the same camera — called the Mars

Hand Lens Imager on that vehicle — for science and for taking selfies.

But combined with SHERLOC, WATSON can do even more: The team can precisely map SHERLOC's findings

over WATSON's images to help reveal how different mineral layers formed and overlap. They can also combine

the mineral maps with data from other instruments — among them, PIXL (Planetary Instrument for X-ray

Lithochemistry) on Perseverance's robotic arm — to see whether a rock could hold signs of fossilized microbial

life.

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Meteorites and Spacesuits

Any science instrument exposed to the Martian environment for long enough is bound to change, either from

the extreme temperature swings or the radiation from the Sun and cosmic rays. Scientists occasionally have to

calibrate these instruments, which they do by measuring their readings against calibration targets —

essentially, objects with known properties selected in advance for cross-checking purposes. (For instance, a

penny serves as one calibration target aboard Curiosity.) Since they know in advance what the readings should

be when an instrument is working correctly, scientists can make adjustments accordingly.

In this test image by SHERLOC, an instrument aboard NASA's Perseverance rover, each color represents a different

mineral detected on a rock's surface. Credits: NASA/JPL-Caltech

About the size of a smartphone, SHERLOC's calibration target includes 10 objects, including a sample of a Martian

meteorite that traveled to Earth and was found in the Oman desert in 1999. Studying how this meteorite

fragment changes over the course of the mission will help scientists understand the chemical interactions

between the planet's surface and its atmosphere. SuperCam, another instrument aboard Perseverance, has a

piece of Martian meteorite on its calibration target as well.

While scientists are returning fragments of Mars back to the surface of the Red Planet to further their studies,

they're counting on Perserverance to gather dozens of rock and soil samples for future return to Earth. The

samples the rover collects will be exhaustively studied, with data taken from the landscape in which they

formed, and they'll include different rock types than the meteorites.

Next to the Martian meteorite are five samples of spacesuit fabric and helmet material developed by NASA's

Johnson Space Center. SHERLOC will take readings of these materials as they change in the Martian landscape

over time, giving spacesuit designers a better idea of how they degrade. When the first astronauts step on to

Mars, they might have SHERLOC to thank for the suits that keep them safe.

Source: NASA Return to Content

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The Night Sky

FRIDAY, JUNE 5

THURSDAY, JUNE 11

The Big Dipper hangs high in the northwest as the stars come out. The Dipper's Pointers, currently its bottom

two stars, point lower right toward Polaris. Above Polaris, and looking very similar to it, is Kochab, the lip of the

Little Dipper's bowl.

Kochab stands precisely above Polaris around the very end of twilight now. How precisely can you time this

event for your location, perhaps using a hanging plumb bob or the vertical edge of a building? Every day it

happens 4 minutes earlier, as with everything among the stars.

FRIDAY, JUNE 12

Mercury remains under Pollux and Castor in twilight, as shown below, but it has now faded to magnitude 1.3.

That's less than half as bright as Procyon, mag 0.4.

Last-quarter Moon tonight (exactly last-quarter at 2:24 a.m. Saturday morning EDT). The Moon rises around 1

or 2 a.m. local daylight-saving time, with bright Mars (magnitude –0.2) shining dramatically orange above or

upper right of it (by about 4°). As Saturday's dawn brightens, they stand high in the southeast.

Source: Sky and Telescope Return to Contents

TUESDAY, JUNE 9

After dark, Vega dominates the eastern sky.

Barely lower left of it is 4th-magnitude Epsilon

Lyrae, the famous Double-Double. Epsilon forms

one corner of a roughly equilateral triangle with

Vega and Zeta Lyrae. The triangle is less than 2°

on a side, hardly the width of your thumb at arm's

length.

Binoculars easily resolve Epsilon. And a 4-inch

telescope at 100× or more should resolve each of

Epsilon's wide components into a tight pair.

Zeta Lyrae is also a double star for binoculars;

much closer and tougher, but plainly resolved in

any telescope.

And Delta Lyrae, below Zeta, is a much wider and

easier pair.

WEDNESDAY, JUNE 10

Arcturus, magnitude 0 – the same as Vega –

shines pale yellow-orange high overhead toward

the south. The kite shape of Bootes, its

constellation, extends up from Arcturus. The kite

is narrow, slightly bent, and 23° long: about two

fists at arm's length.

Just east (left) of the Bootes kite is Corona

Borealis, the pretty but mostly dim Northern

Crown. It has only one modestly bright star, 2nd-

magnitude Alphecca or Gemma: its crown jewel.

Mercury remains under Pollux and Castor in twilight, though at magnitude 1.3 it no longer outshines even Pollux,

magnitude 1.2. In fact Mercury will appear even fainter considering the greater atmospheric extinction at its lower

altitude and the brighter sky there too. Binoculars may help.

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ISS Sighting Opportunities (from Denver)

No sightings at Denver through Tuesday Jun 16, 2020

Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Time Zone)

NASA TV Schedule for Week of June 8

Live Programming

June 11, Thursday

10:35 a.m. – International Space Station Expedition 63 in-flight interview with KNX NewsRadio, Los

Angeles and Commander Chris Cassidy of NASA (All Channels)

June 12, Friday

11 a.m. - SpaceCast Weekly (All Channels)

Watch NASA TV online by going to the NASA website. Return to Contents

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Space Calendar

Jun 09 - Apollo Asteroid 2013 EC20 Near-Earth Flyby (0.067 AU)

Jun 09 - Virtual Meeting: Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020) -

Presentation on Radio-Frequency Interference

Jun 10 - Amor Asteroid 2020 KY Near-Earth Flyby (0.044 AU)

Jun 10 - Online Lecture: Alcohol in Space

Jun 10 - Lecture: The Hubble Space Telescope - Unveiling an Incredible Universe, Washington DC

Jun 10 - UK Launch Vehicles Webinar

Jun 10 - Online Webinar: Rethinking PAROS and Looking Ahead at Multilateral Approaches

Jun 10 - Online Colloquium: Pulsar Observation and Study with FAST and the Parkes Radio Telescope

Jun 11 - ELanA 32 (ANDESITE) Electron Launch

Jun 11 - Amor Asteroid 2020 JS1 Near-Earth Flyby (0.025 AU)

Jun 11 - Amor Asteroid 2020 JQ2 Near-Earth Flyby (0.039 AU)

Jun 11 - Webinar: Setting the Scene - The Climate Resilience Challenge and How ESA is Responding

Jun 11 - Live Chat: The Dragonfly Mission to Titan

Jun 11-12 - International Conference on Astroparticle Physics and Higgs Physics (ICAPHP 2020),

Copenhagen, Denmark

Jun 11-13 - AGU-SEG Airborne Geophysics Workshop, Davie, Florida

Jun 12 - Mars Passes 1.7 Degrees From Neptune

Jun 12 - Webinar: Emerging Space Program - Lessons Learned for the Future

Jun 13 - Starlink 8 (60)/ SkySat 16-18 Falcon 9 Launch

Jun 13 - Amor Asteroid 2020 KB3 Near-Earth Flyby (0.008 AU)

Jun 13 - Apollo Asteroid 2020 JU1 Near-Earth Flyby (0.049 AU)

Jun 13 - Atira Asteroid 2010 XB11 Closest Approach To Earth (0.706 AU)

Jun 13 - 10th Anniversary (2010), Hayabusa (MUSES-C) Return To Earth

Jun 13-19 - Summer School: Matrix Membranes and Emergent Spacetime, Dublin, Ireland

Source: JPL Space Calendar Return to Contents

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Food for Thought

Was Interstellar Oumuamua a Dark Hydrogen Iceberg?

Artist’s impression of the interstellar object, `Oumuamua, experiencing outgassing as it leaves our Solar System. Credit:

ESA/Hubble, NASA, ESO, M. Kornmesser

When Canadian astronomer Robert Weryk discovered `Oumuamua passing through our Solar System with the Pan-

STARRS telescope, in October 2017, it caused quite a stir. It was the first interstellar object we’d ever seen coming

through our neighborhood. The excitement led to speculation: what could it be?

There was lots of fun conjecture on its origins. Was it an alien spacecraft? A solar sail? Or something more prosaic?

As more observational evidence rolled in, ideas on `Oumuamua’s nature followed. Was it a comet? It had no coma,

so some thought it was a partially disintegrated comet, or an extrasolar comet. Could it be an asteroid?

`Oumuamua was similar to asteroids in some respects, like its rotation rate. But it was an elongated cigar-shaped

object, not round.

As time went on, more studies came out, their thoroughness hampered by `Oumuamua’s brief appearance in our

Solar System, and by limited opportunity for observations. A 2019 study suggested that the object was indeed the

fragment of a larger disintegrated interstellar comet.

Then in April 2020 a pair of researchers published another study on `Oumuamua. They confirmed the extrasolar

origin of `Oumuamua, saying that it was a fragment of a larger parent body, torn apart by tidal forces when it got

too close to its star and trespassed on the Roche limit. `Oumuamua was sent on a trajectory out of its solar system

of origin, into ours.

Now, a new study presents evidence suggesting a different origin for our first interstellar visitor: It’s not a fragment

of a much larger body, but a chunk of frozen hydrogen. A space iceberg.

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The new study is titled “Evidence that 1I/2017 U1 (‘Oumuamua) was composed of molecular hydrogen ice.” The

authors are Darryl Seligman (Dep’t. of Geosciences, University of Chicago) and Gregory Laughton (Dep’t. of

Astronomy, Yale University.) The paper has been accepted for publication in The Astrophysical Journal Letters.

“It’s a frozen iceberg of molecular hydrogen,” said Seligman in a press release. “This explains every mysterious

property about it. And if it’s true, it’s likely that the galaxy is full of similar objects.”

`Oumuamua was difficult to observe. It was on its way out of our Solar System when it was discovered. It had

already gone past the Sun, and its trajectory showed that it came from outside our Solar System, and would never

return.

The object also accelerated, and there was no gravitational reason why it should. That led to some conjecture that

it was a comet, since comets sometimes accelerate as they approach the Sun, due to off-gassing. But that leaves a

coma, and `Oumuamua didn’t have one.

Then in 2019, the authors of this new study published, with Konstantin Batygin, a paper titled “On the Anomalous

Acceleration of 1I/2017 U1 `Oumuamua.” That work showed that Oumuamua was indeed a comet, just an unusual

type of comet.

At the time, Seligman told NBC News, “We are quite confident in our hypothesis, and do not believe that there is a

need to rely on alternative, less likely explanations for the non-gravitational acceleration.” At the same time, co-

author Batygin told NBC News, “What our paper demonstrates is that some of its remarkable properties can be

understood within the framework of relatively standard cometary physics.”

In their new paper, Seligman and Laughton have refined that idea, writing “We show that all of ‘Oumaumua’s

observed properties can be explained if it contained a significant fraction of molecular hydrogen (H2) ice.”

In a press release, Seligman added that “The only kind of ice that really explains the acceleration is molecular

hydrogen.”

Molecular hydrogen ice has some strange properties. It only forms at a specific temperature, -259.14 °C, which is

only a little above absolute zero, which is -273.15 °C. When it sublimates, it neither produces light nor reflects light.

That’s what makes it so hard to spot with telescopes.

The sublimation of the molecular hydrogen ice explains `Oumuamua’s acceleration. In their paper, Seligman and

Laughton explain that “H2 sublimation at a rate proportional to the incident solar flux generates a surface-covering

jet that reproduces the observed acceleration.”

The authors say that the molecular hydrogen ice also explains `Oumuamua’s strange cigar shape, unusual for an

object in space. They write “Mass wasting from sublimation leads to monotonic increase in the body axis ratio,

explaining ‘Oumuamua’s shape.”

In the press release, Seligman explained it in plain language: “Imagine what happens to a bar of soap. It starts out

as a fairly regular rectangle, but as you use it up, it gets smaller and thinner over time.”

This explanation begs the question: How many more of these objects are there? Are they common? Quite likely, the

researchers say.

“That we saw one at all implies that there’s a ton of these things out there,” Seligman said. “The galaxy must be

filled with these dark hydrogen icebergs. That’s incredibly cool.”

The next question is, where did it come from? Where and how do these hydrogen icebergs form?

There aren’t many possibilities, according to Seligman and Laughton. They say that `Oumuamua likely formed in a

Giant Molecular Cloud (GMC), the same structure that stars form from. GMCs are massive structures of freezing

hydrogen, between 15 to 600 light years across with some helium present as well.

This is what makes `Oumuamua even more exciting.

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It’s very difficult, even impossible, to see what’s going on inside these dense clouds. Their cores are hidden from

view. That means that `Oumuamua, and other objects like it, should hold clues to what’s going on inside GMCs. If

there was some way to intercept one of these objects, we could learn a lot.

“It would be the most pristine primordial matter in the galaxy. It’s like the galaxy made it, and FedExed it out

straight to us,” said Seligman.

If Seligman and Laughton are correct, then we should keep our telescopic eyes open for the next `Oumuamua that

comes through our system. Since they say that the object got its cigar shape from travelling through our Solar

System, if we spot the next one soon enough, we can verify their theory and watch it take on a cigar shape as it

moves through our neighborhood.

Fortunately for all of us, a telescope ideally equipped to spot all kinds of transient objects is about to see first light.

Sometime later this year, the Vera Rubin Observatory, formally known as the Large Synoptic Survey Telescope, will

come online. That telescope’s wide field of view and 8.4 meter primary mirror will image the entire available sky

every few nights, and catalogue 90% of near-Earth objects larger than 300m.

It’ll also spot supernovae, Kuiper Belt Objects, and other transients. If another `Oumuamua comes, it’s a fair bet

that the Vera Rubin Observatory will spot it.

Though `Oumuamua was the first one of these hydrogen icebergs we’ve spotted, that fact alone doesn’t tell us

much about their abundance. The authors think there’s likely a great number of these objects, and that their

numbers has consequences for planet formation.

“If ‘Oumuamua’s anomalous acceleration stemmed from sublimating H2 ice, it is likely that a large population of

similar objects exists,” they write in their paper. “An analysis by Do et al. (2018) suggests that the space density of

‘Oumuamua-like objects is n = 0.2 AU-3. Our estimate of ‘Oumuamuas initial mass thus suggests a total mass of ~ 1

Earth mass of H2-rich bodies per star. A galactic sea of unbound planetesimal-sized objects has potential

consequences for star and planet formation.”

Source: Universe Today Return to Contents

An image from the paper showing the

evolution of Oumuamua’s size and shape as it traverses our Solar System. H2 sublimation and its

trajectory through the Solar System has

changed the object. Pairs of orientations at three discrete points on the trajectory are shown in the upper left. Image Credit:

Seligman et al, 2020.

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Space Image of the Week

Halo of the Cat's Eye Image Credit & Copyright: R. Corradi (Isaac Newton Group), Nordic Optical Telescope

Explanation: The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its haunting symmetries are seen in the very central region of this stunning false-color picture, processed to reveal the enormous but extremely faint halo of gaseous material, over three light-years across, which surrounds the brighter, familiar planetary nebula. Made with data from the Nordic Optical Telescope in the Canary Islands, the composite picture shows extended emission from the nebula. Planetary nebulae have long been appreciated as a final phase in the life of a Sun-like star. Only much more recently however, have some planetaries been found to have halos like this one, likely formed of material shrugged off during earlier active episodes in the star's evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years.

Source: NASA APOD Return to Contents