1 of 14

Space News Update — March 31, 2020 —

Contents

In the News

Story 1:

NASA Selects Mission to Study Causes of Giant Solar Particle Storms

Story 2:

Are the Gaps in These Disks Caused by Planets?

Story 3:

Comet ATLAS: Will It Become a Naked-Eye Object?

Departments

The Night Sky

ISS Sighting Opportunities

NASA-TV Highlights

Space Calendar

Food for Thought

Space Image of the Week

2 of 14

1. NASA Selects Mission to Study Causes of Giant Solar Particle Storms

A new NASA mission called SunRISE will study what drives solar particle storms – giant surges of solar particles that erupt

off of the Sun – as depicted in this illustration. Understanding how such storms affect interplanetary space can help

protect spacecraft and astronauts. Credits: NASA

NASA has selected a new mission to study how the Sun generates and releases giant space weather storms –

known as solar particle storms – into planetary space. Not only will such information improve understanding of

how our solar system works, but it ultimately can help protect astronauts traveling to the Moon and Mars by

providing better information on how the Sun’s radiation affects the space environment they must travel

through.

The new mission, called the Sun Radio Interferometer Space Experiment (SunRISE), is an array of six

CubeSats operating as one very large radio telescope. NASA has awarded $62.6 million to design, build and

launch SunRISE by no earlier than July 1, 2023.

NASA chose SunRISE in August 2017 as one of two Mission of Opportunity proposals to conduct an 11-month

mission concept study. In February 2019, the agency approved a continued formulation study of the mission

for an additional year. SunRISE is led by Justin Kasper at the University of Michigan in Ann Arbor and managed

by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

"We are so pleased to add a new mission to our fleet of spacecraft that help us better understand the Sun, as

well as how our star influences the space environment between planets," said Nicky Fox, director of NASA's

Heliophysics Division. "The more we know about how the Sun erupts with space weather events, the more we

can mitigate their effects on spacecraft and astronauts."

The mission design relies on six solar-powered CubeSats – each about the size of a toaster oven – to

simultaneously observe radio images of low-frequency emission from solar activity and share them via NASA’s

Deep Space Network. The constellation of CubeSats would fly within 6 miles of each other, above Earth's

atmosphere, which otherwise blocks the radio signals SunRISE will observe. Together, the six CubeSats will

3 of 14

create 3D maps to pinpoint where giant particle bursts originate on the Sun and how they evolve as they

expand outward into space. This, in turn, will help determine what initiates and accelerates these giant jets of

radiation. The six individual spacecraft will also work together to map, for the first time, the pattern of

magnetic field lines reaching from the Sun out into interplanetary space.

NASA's Missions of Opportunity maximize science return by pairing new, relatively inexpensive missions with

launches on spacecraft already approved and preparing to go into space. SunRISE proposed an approach for

access to space as a hosted rideshare on a commercial satellite provided by Maxar of Westminster, Colorado,

and built with a Payload Orbital Delivery System, or PODS. Once in orbit, the host spacecraft will deploy the six

SunRISE spacecraft and then continue its prime mission.

Missions of Opportunity are part of the Explorers Program, which is the oldest continuous NASA program

designed to provide frequent, low-cost access to space using principal investigator-led space science

investigations relevant to the Science Mission Directorate’s (SMD) astrophysics and heliophysics programs. The

program is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for SMD, which conducts

a wide variety of research and scientific exploration programs for Earth studies, space weather, the solar

system and universe.

Credit: NASASPAceflight.com

Source: NASA Return to Contents

4 of 14

2. Are the Gaps in These Disks Caused by Planets?

The column on the left shows gas distribution in five of the circumstellar debris disks in the study. On the right are

measurements for gas in those disks in different velocity channels. Those images show “velocity kinks.” Image Credit: C.

Pinte et al, 2020.

Astronomers like observing distant young stars as they form. Stars are born out of a molecular cloud, and once

enough of the matter in that cloud clumps together, fusion ignites and a star begins its life. The leftover material

from the formation of the star is called a circumstellar disk.

As the material in the circumstellar disk swirls around the now-rotating star, it clumps up into individual planets. As

planets form in it, they leave gaps in that disk. Or so we think.

One of the most observed young stars is called HL Tauri. It’s in the constellation Taurus and is about 450 light years

away. The Atacama Large Millimeter Array (ALMA) captured a well-known image of HL Tauri in 2014. That image is

the sharpest image ever taken by ALMA.

5 of 14

Since then, astronomers have observed other young stars, and also found gaps in their disks. Note that ALMA, as its

name tells us, is not a visible light telescope. There’s so much gas and dust in circumstellar disks that visible light is

useless for studying them. ALMA observes in wavelengths of light between infrared and radio waves, so it can see

into the swirling disk of gas and dust.

A new study looked at 18 young stars and their disks, and found evidence that 8 of those stars have what they call

“velocity kinks” that may signal the presence of young, still-forming planets. The study is titled “Nine Localized

Deviations from Keplerian Rotation in the DSHARP Circumstellar Disks: Kinematic Evidence for Protoplanets Carving

the Gaps.” Lead author of the study is Christophe Pinte of Monash University, Australia, and the University of

Grenoble Alpes, France). The paper is published in The Astrophysical Journal Letters.

Though astronomers can see the gaps in circumstellar disks, they can’t see the planets. After years of trying with

some of the world’s best telescopes, astronomers have only directly imaged a single exoplanet in a gap around one

star. So even though it might seem obvious that baby planets are responsible, and there’s really no other way they

could form, it’s still an unproven theory. This new study helps make the case that at least some of the observed

gaps in circumstellar disks are caused by planets.

This study used data from the Disk Substructures at High Angular Resolution (DSHARP) project. DSHARP uses ALMA

to study nearby bright circumstellar disks (also called protoplanetary disks). According to the website, DSHARP is

“designed to assess the prevalence, forms, locations, sizes, and amplitudes of small-scale substructures in the

distributions of the disk material and how they might be related to the planet formation process.”

There are other candidate explanations for the gaps in the disks. One is snow lines, or frost lines. In a circumstellar

debris disk, a frost line is the distance from the star where it’s cold enough for volatiles to freeze. This includes not

only water ice, but also ammonia, methane, carbon dioxide and others. Beyond the frost line, these substances

freeze into solid ice grains.

This is the sharpest image ever taken by

ALMA — sharper than is routinely achieved in visible light with the

NASA/ESA Hubble Space Telescope. It shows the

protoplanetary disc surrounding the young

star HL Tauri. With young stars like this one, and CI Tau, the observations reveal

substructures within the disc that have never

been seen before and even show the possible

positions of planets forming in the dark patches within the

system. In this picture the features seen in the

HL Tauri system are labelled. Credit: ALMA

(ESO/NAOJ/NRAO)

6 of 14

Another possible explanation for these gaps is dust grain sintering. That’s when dust compacts into a solid structure

through heat and pressure, but without melting. A team of scientists explored that idea in this paper.

Other candidates include magneto-hydrodynamic effects, zonal flows, and self-induced dust traps. After the 2014

ALMA image of HL Tauri and its rings, researchers published a number of papers presenting evidence in favor of all

of these possible explanations.

But none of them are as intriguing as the baby planet explanation. And since we now know that most, if not all,

stars host exoplanets, it makes sense.

ALMA doesn’t just take pictures of these young stars and their debris disks. It uses its power to study the gas

distribution in the disks. The image below is from the new study. It compares gas distribution in five disks with

velocity measurements of the same disk.

At the heart of this new study are what’s called “velocity kinks.”

The circumstellar debris disk around HL Tauri and other young stars is largely made of gas, and it’s rotating. As it

rotates, its movement is governed by Keplerian velocity. Keplerian velocity describes how a disk of material should

move when it’s dominated by a massive body at its center. But as the image above shows, there are kinks in the

gas. According to the authors of the new paper, these kinks are evidence of young planets.

From the paper: “Embedded planets perturb the Keplerian gas flow in their vicinity, launching spiral waves at

Lindblad resonances both inside and outside their orbits.”

For at least one of the 20 young stars, the disrupted flow is evidence of large gas giants: “Accurate measurements

of rotation curves revealed, for instance, radial pressure gradients and vertical flows, likely driven by gaps carved in

the gas surface density by Jupiter-mass planets in the disk of HD 163296.”

The study presents a lot of strong evidence in support of protoplanets. But the authors acknowledge that there

could be other causes. One of them is in the data itself.

“Several observational effects and physical mechanisms may produce features in the channel maps that look like

velocity kinks,” the authors say. “The most obvious one is the reconstruction process at low signal-to-noise ratio

that often results in patchy emission that could be mistaken for kinks. We cannot exclude that such artifacts are

present in the DSHARP data…”

But they’ve taken steps to eliminate those errors, and in the end of their paper they make several statements in

summary:

“We found nine localized (channel-specific) velocity perturbations indicative of non-Keplerian motion in

DSHARP observations of 8 protoplanetary disks, out of the 18 selected sources.”

“The presence of embedded planets would naturally explain both the continuum rings and gas velocity

deviations from Keplerian rotation.”

“If planets are indeed responsible for these tentative velocity kinks, they should have masses of the order of

a Jupiter mass.”

In several cases, the authors couldn’t reach definitive conclusions. “… non-detections in other disks or in

other gaps in disks where we detected a kink do not necessarily imply the absence of Jupiter-mass planets.”

So there we have it. This thorough and interesting paper advances the idea that gaps in circumstellar debris disks

are indeed caused by baby planets.

As our observing power grows, and as telescopes like the James Webb and others become operational, the

evidence will likely grow more conclusive.

Source: Universe Today Return to Contents

7 of 14

3. Comet ATLAS: Will It Become a Naked-Eye Object?

Glowing aqua from carbon and cyanogen emissions and sprouting a 15′ long tail, Comet ATLAS passes near Rho (ρ)

Ursae Majoris on March 22nd. Its coma has ballooned in recent days to 15′ across, which at its current distance is equal

to half the size of the Sun. South is up. Gerald Rhemann

Not since Comet 46P/Wirtanen passed near the Pleiades star cluster in December 2018 has a naked-eye comet

graced the night sky. That may soon change. On December 28, 2019, astronomers with the automated Asteroid

Terrestrial-impact Last Alert System (ATLAS) survey discovered a 20th-magnitude comet in Ursa Major that was

subsequently named Comet ATLAS (C/2019 Y4).

Once a reasonable orbit was determined, Comet ATLAS proved a close match to the Great Comet of 1844 (C/1844

Y1). Both have periods around 4,000 years, approach within 0.25 astronomical unit (a.u.), or 37.4 million

kilometers, of the Sun at perihelion, and are inclined 45° to the ecliptic. These and other orbital similarities were

strong enough to conclude that both objects were fragments of a single, much larger comet that broke apart about

5,000 years ago. For all we know there may be additional fragments en route for future appearances.

Comet ATLAS’s orbit is

tilted 45° with respect to

the plane of the planets.

Closest approach to the

Earth occurs on May

23rd (116.7 million

kilometers), prior to its

May 31st perihelion.

NASA / JPL Horizons

8 of 14

Because the Great Comet reached 2nd magnitude and grew a 10° tail in January 1845 many of us wondered if its

sibling might be capable of doing the same. The answer is a qualified "yes." But one thing is certain — the comet is

brightening exponentially.

How Bright Will Comet ATLAS Be? While a hundredfold increase in brightness in a month makes a comet

lover's heart palpitate, it could also mean that the comet's volatile ices are rapidly vaporizing as it nears the Sun.

Once those materials are depleted some astronomers expect Comet ATLAS's brightness curve to flatten out, a

common occurrence in comets that have rarely or never come close to the Sun before. Long-period comets that

approach within 1 a.u. of our star have been known to split apart, disintegrate, and disappear. Comet ISON (C/2012

S1) offers a classic example. Shortly before its November 2013 perihelion, the comet crumbled into a cloud of dust

and ice, dashing hopes for the spectacle so many of us had anticipated.

According to NASA’s JPL Horizons the comet could reach magnitude –5, exceeding Venus in brightness at perihelion

on May 31st. Because it will lie 13° southwest of the Sun at that time, it might be possible to see the object in

broad daylight with a properly shielded telescope.

That prediction may be overly optimistic however. In a March 19th notice from the Central Bureau for Astronomical

Telegrams (CBAT), Director Daniel Green applied a formula based on the behavior of previous long-period, Sun-

hugging comets and derived a more conservative peak magnitude of –0.3.

It's good news either way. In both predictions Comet ATLAS will reach naked-eye brightness in mid-May before it's

lost in the solar glare. The JPL Horizons formula predicts a peak magnitude between 1 and 2, while Green

anticipates that number to be between 2 and 3. During the first half of May the comet will appear low in the

evening sky at dusk and early nightfall as it tracks through Perseus. Binoculars should reveal a bright, strongly

condensed coma followed by dust and gas tails pointing away from the Sun. With a little luck we might even see

the tail without optical aid.

After rounding the Sun, Comet ATLAS returns to view around June 15th at dawn in Orion for Southern Hemisphere

skywatchers. Initially glowing at magnitude 3 or 4, the comet will fade quickly — assuming it survives a sizzling

perihelic encounter!

For now, observers in the Northern Hemisphere can follow the comet from Ursa Major through Camelopardalis with

a 6-inch or larger telescope. While visible in binoculars the comet is still quite diffuse and takes some effort to see.

That should change soon.

The comet remains a circumpolar object for much of the U.S. and Europe until about two weeks before perihelion,

when best viewing will be during the early evening hours. If the comet is especially dusty, we'll likely see a more

spectacular tail instead of a bright, spiked fuzz ball. Be hopeful, but as always when it comes to these fragile

objects, temper your expectations.

Source: Sky and Telescope Return to Contents

The chart shows the

position of Comet ATLAS

(C/2019 Y4) through April

24th at 0h UT for the dates

shown. As the comet

approaches perihelion, we'll

be providing updated

charts. Sky & Telescope

9 of 14

The Night Sky

Friday, April 3

Venus this evening shines right in the left edge of the Pleiades! How soon before the end of twilight can

you first begin to see the little cluster? Bring out your telescope, binoculars, and/or long-focus camera!

Of course they're nowhere near each other, really. Venus this evening is 5.2 light-minutes from us, while

the Pleiades are 440 light-years in the background. That's 150 million times farther. To put that in

perspective: If Venus was a mark on your eyeglasses a half inch from your eye, the Pleiades would be

1,200 miles away in front of it − and 30 miles from side to side.

Saturday, April 4

This evening look right or lower right of the Moon for Regulus, the leading star of Leo. They're about 5°

apart for North America. Above the Moon by a similar distance or a bit more is Algieba, the second-

brightest star after Regulus in the Sickle of Leo The Sickle, a backward question mark, forms the Lion's

stick-figure's head, neck, chest, and front foot.

Source: Sky and Telescope Return to Contents

On the evening of Friday April 3rd, the Pleiades seem to leak out of Venus! As seen from most of North America, they spill to the lower right.

Tuesday, March 31 First-quarter Moon (exactly so at 6:21

a.m. Wednesday morning EDT). The

Moon is in the feet of Gemini. After

dark you'll find Orion far below it,

Procyon off to its left, and brighter

Capella farther to its right. More or

less above the Moon are Gemini's

head stars, Pollux and Castor.

Wednesday, April 1 The Moon after dark shines high below

Pollux. Farther lower left of the Moon

is brighter Procyon. Far below Procyon

is Sirius, the brightest star in the night.

Thursday, April 2 Look left of the Moon this evening for

Pollux and Castor. Farther below the

Moon are Procyon, the Little Dog Star,

and farther down Sirius, the big Dog

Star. The three form a tall, nearly

vertical line.

10 of 14

ISS Sighting Opportunities (from Denver)

Date Visible Max Height Appears Disappears

Tue Mar 31, 7:57 PM 3 min 13° 10° above NNW 10° above NE

Tue Mar 31, 9:33 PM 1 min 25° 15° above NW 25° above NNW

Wed Apr 1, 8:46 PM 3 min 26° 11° above NNW 24° above NE

Thu Apr 2, 7:59 PM 5 min 20° 10° above NNW 11° above ENE

Thu Apr 2, 9:36 PM < 1 min 34° 22° above WNW 34° above WNW

Fri Apr 3, 8:49 PM 3 min 67° 22° above NW 47° above E

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

NASA-TV Highlights (all times Eastern Time Zone)

April 1, Wednesday

4 p.m. - Video file of the International Space Station Expedition 63 Crew’s pre-launch activities at the

Baikonur Cosmodrome in Kazakhstan (Cassidy, Ivanishin, Vagner; includes material recorded from March

24-April 1) - Johnson Space Center via Baikonur, Kazakhstan (Media Channel)

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

11 of 14

Space Calendar

Mar 31 - Mars Passes 0.9 Degrees From Saturn

Mar 31 - Amor Asteroid 2020 FB4 Near-Earth Flyby (0.031 AU)

Mar 31 - Apollo Asteroid 2020 FA1 Near-Earth Flyby (0.047 AU)

Mar 31 - Atira Asteroid 2013 TQ5 Closest Approach To Earth (0.412 AU)

Mar 31 - 15th Anniversary (2005), Mike Brown, et al's Discovery of Dwarf Planet Makemake

Mar 31 - 1620th Anniversary (400 AD), Comet C/400 F1 Near-Earth Flyby (29.8 Lunar Distance)

Mar 31-Apr 02 - Space Science Week

Apr 01 - Astro2020 Teleconference: Panel on Cosmology

Apr 01 - 60th Anniversary (1960), Tiros 1 Launch (1st Weather Satellite)

Apr 01-07 - Conference: Protostar and Planets VII, Kyoto, Japan

Apr 02 - Apollo Asteroid 2020 FG6 Near-Earth Flyby (0.014 AU)

Apr 02 - Apollo Asteroid 2019 GM1 Near-Earth Flyby (0.023 AU)

Apr 02 - 175th Anniversary (1845), 1st Photo of Sun taken by Louis Fizeau & Leon Foucault

Apr 03 - Mercury Passes 1.4 Degrees From Neptune

Apr 03 - Venus Passes 0.3 Degrees from the Pleiades

Apr 03 - Apollo Asteroid 2020 FK3 Near-Earth Flyby (0.027 AU)

Apr 04 - Apollo Asteroid 2020 FL6 Near-Earth Flyby (0.013 AU)

Apr 04 - Apollo Asteroid 2015 FC35 Near-Earth Flyby (0.027 AU)

Source: JPL Space Calendar Return to Contents

TIROS Weather Satellite

Left, Credit: Smithsonian

Right Credit:

NOAA

12 of 14

Food for Thought

Planetary Defenders Validate Asteroid Deflection Code

Lawrence Livermore researchers compared results of asteroid deflection simulations to experimental data and found that

the strength model has a substantial effect on momentum transferred.

Planetary defense researchers at Lawrence Livermore National Laboratory (LLNL) continue to validate their ability to

accurately simulate how they might deflect an Earth-bound asteroid in a study that will be published in the April

issue of the American Geophysical Union journal Earth and Space Science.

The study, led by LLNL physicist Tané Remington, also identified sensitivities in the code parameters that can help

researchers working to design a modeling plan for the Double Asteroid Redirection Test (DART) mission in 2021,

which will be the first-ever kinetic impact deflection demonstration on a near-Earth asteroid.

Asteroids have the potential to impact Earth and cause damage at the local to global scale. Humankind is capable of

deflecting or disrupting a potentially hazardous object. However, due to the limited ability to perform experiments

directly on asteroids, understanding how multiple variables might affect a kinetic deflection attempt relies upon

large-scale hydrodynamic simulations thoroughly vetted against relevant laboratory‐scale experiments.

“We’re preparing for something that has a very low probability of happening in our lifetimes, but a very high

consequence if it were to occur,” Remington said. “Time will be the enemy if we see something headed our way

one day. We may have a limited window to deflect it, and we will want to be certain that we know how to avert

disaster. That’s what this work is all about.”

13 of 14

This study investigated the accuracy of the codes by comparing simulation results to the data from a 1991

laboratory experiment conducted at Kyoto University, where a hyper-velocity projectile impacted a basalt sphere

target.

Remington used an adaptive smoothed-particle hydrodynamics code named Spheral to produce simulation results

that closely resemble the experimental findings. The simulations also helped the researchers identify which models

and material parameters are most important to accurately simulate impact scenarios with a brittle, rocky asteroid.

They found that selection of the strength model and its parameters had a substantial effect on the predicted crater

size and the amount of momentum transferred into the target asteroid. In addition to the strength model, the team

found that simulation results also are sensitive to strain models and material parameters.

These findings highlight the link between having properly validated codes and having the confidence needed to

effectively plan a deflection mission. While no asteroids pose an immediate threat to Earth, LLNL researchers are

collaborating with the National Nuclear Security Administration and NASA in the development of a modeling plan for

the DART mission. These findings will help the team hone its modeling plan for DART.

The DART spacecraft will launch in late July 2021. The target is a binary (two asteroids orbiting each other) near-

Earth asteroid named Didymos that is being intensely observed using telescopes on Earth to precisely measure its

properties before impact. The DART spacecraft will deliberately crash into the smaller moonlet in the binary asteroid

— dubbed Didymoon — in September 2022 at a speed of approximately 6.6 kilometers/second. The collision will

change the speed of the moonlet in its orbit around the main body by a fraction of 1 percent, but this will change

the orbital period of the moonlet by several minutes — enough to be observed and measured using telescopes on

Earth.

“This study suggests that the DART mission will impart a smaller momentum transfer than previously calculated,”

said Mike Owen, LLNL physicist, coauthor on the paper and developer of the Spheral code. “If there were an Earth-

bound asteroid, underestimating momentum transfer could mean the difference between a successful deflection

mission and an impact. It’s critical we get the right answer. Having real world data to compare to is like having the

answer in the back of the book.”

Schematic of the DART mission shows the impact on the moonlet of asteroid (65803) Didymos. Post-impact observations

from Earth-based optical telescopes and planetary radar would, in turn, measure the change in the moonlet’s orbit about

the parent body. Credits: NASA/Johns Hopkins Applied Physics Lab

Source: Lawrence Livermore National Laboratory Return to Contents

14 of 14

Space Image of the Week

A 212-Hour Exposure of Orion

Image Credit & Copyright: Stanislav Volskiy, Rollover Annotation: Judy Schmidt

Explanation: The constellation of Orion is much more than three stars in a row. It is a direction in space that is rich with impressive nebulas. To better appreciate this well-known swath of sky, an extremely long exposure was taken over many clear nights in 2013 and 2014. After 212 hours of camera time and an additional year of processing, the featured 1400-exposure collage spanning over 40 times the angular diameter of the Moon emerged.

Of the many interesting details that have become visible, one that particularly draws the eye is Barnard's Loop, the bright red circular filament arcing down from the middle. The Rosette Nebula is not the giant red nebula near the top of the image -- that is a larger but lesser known nebula known as Lambda Orionis. The Rosette Nebula is visible, though: it is the red and white nebula on the upper left. The bright orange star just above the frame center is Betelgeuse, while the bright blue star on the lower right is Rigel. Other famous nebulas visible include the Witch Head Nebula, the Flame Nebula, the Fox Fur Nebula, and, if you know just where to look, the comparatively small Horsehead Nebula. About those famous three stars that cross the belt of Orion the Hunter -- in this busy frame they can be hard to locate, but a discerning eye will find them just below and to the right of the image center.

Source: NASA APOD Return to Contents