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Space News Update — December 30, 2014 —

Contents

In the News

Story 1:

Ratchet Wrench ‘E-mailed’ to Space Station

Story 2:

15 Amazing Space Missions to Watch in 2015

Story 3:

Signs of Europa Plumes Remain Elusive in Search of Cassini Data

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. Ratchet Wrench ‘E-mailed’ to Space Station

Astronaut Barry “Butch” Wilmore shows off the 3D printed ratchet wrench on the International Space Station. Credit:

NASA

A future where mission control can digitally dispatch tools, spare parts and other vital materials to far-flung

space crews took one giant leap toward reality when a 3D printer aboard the International Space Station

produced a ratchet wrench on demand.

The 3D printer has been on the space station since it launched on an automated SpaceX supply ship in

September, printing test coupons designed to prove the device functions in the weightless environment more

than 200 miles above Earth.

On Dec. 17, engineers took the demonstrations a step further, uplinking a custom-made digital design file of a

ratchet wrench to a laptop attached to the printer.

The ratchet is the first “uplink tool” produced by the 3D printer, according to Made in Space, a Silicon Valley

startup that partnered with NASA to build and test the machine.

So far, the printer has only made things that were designed before it launched and tested on an identical

machine on the ground. The ratchet produced Dec. 17 is an “uplink tool” that was designed, qualified, tested

and printed in space in less than a week, according to Made in Space.

“The ‘uplink’ is the way we communicate with the ISS crew using a transmitting frequency from Earth to the

International Space Station,” Made in Space wrote in a blog post. “Therefore an uplink tool refers to a tool

design that was transmitted to the space station via the uplink and manufactured on-demand in space.”

The 3D printer works by extruding a special type of hot plastic — known as acrylonitrile butadiene styrene, or

ABS — into layers to form a three-dimensional object. Engineers can upload the specifications of the finished

product to the printer’s computer controller, which oversees the unit’s production.

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Made in Space engineer Noah Paul-Gin created the ratchet design on Autodesk Inventor, a computer-aided

design application, at the company’s ground station in California.

“During the rapid prototyping process, Noah realized that rounded edges and finger grooves on the handle

would make the tool more ergonomic and improve the grip,” Made in Space said in a blog post. “The ratchet

was designed as one print with moveable parts without any support material. The parts and mechanisms of

the ratchet had to be enclosed to prevent pieces from floating in the microgravity environment.”

When Made in Space was satisfied with the design, they sent the file to NASA for a safety check. NASA then

emailed the socket wrench’s specs to a laptop connected to the 3D printer.

The wrench took about four hours to print, Made in Space officials said. It will not be used by the astronauts

but will be returned to Earth for inspection and analysis to see how the 3D printer in space compares to the

performance of an exact copy of the device on the ground.

Astronaut Barry “Butch” Wilmore displayed the finished ratchet wrench in a photo sent back to Earth.

The demo printer does not require much attention by the astronauts, who only need to set up the system and

remove the printed part at the end of the process.

Assuming the testbed works, a second 3D printer is on track for liftoff to the space station next year. It will be

available for use by NASA, international space agencies and commercial users, according to Jason Dunn, co-

founder and chief technology officer of Made in Space.

Aaron Kemmer, another Made in Space co-founder, tweeted Sunday that the company has completed the

design phase of the second 3D printer.

For future missions into deep space — where supply lines with Earth may be thin — astronauts could use 3D

printers to manufacture spare parts.

3D printing in space would avoid putting parts through the intense shaking and noise of launch, and it could

allow engineers to design and build components on the fly as parts break down in space.

Future printers could manufacture whole structures for CubeSats, tools, medical gear, exercise equipment and

other items to keep the space station operating.

“It’s especially important when we consider human space exploration,” said Niki Werkheiser, NASA’s manager

for the 3D Printing in Zero-G project. “From day one, the supply chain has been very constrained. We have to

launch every single thing we ever need from Earth, so being able to make what you need on orbit — when

you need it — is a real game changer.”

Source: SpaceflightNow Return to Contents

The ratchet wrench was designed by Noah Paul-Gin, an engineer at Made In Space Inc., a northern California company that NASA contracted to design, build and operate the printer. Paul-Gin created a 3-D model of the ratchet and made several wrenches, such as the one shown here on an identical printer. Image Credit: Made In Space

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2. 15 Amazing Space Missions to Watch in 2015

The European Space Agency is expected to launch a test flight of its reusable Intermediate eXperimental Vehicle (IXV) in

2015. Credit: ESA-J. Huart, 2012

Space fans have a lot to look forward to next year.

Closely watched spacecraft are expected to start pumping out science, while private spaceflight companies

have a number of launches on the books for 2015. A Mars rover will celebrate its third anniversary chugging

along on the Red Planet, and a Japanese spacecraft will have another chance to make it into orbit around

Venus. Next year could also mark the return of Orbital Sciences Corp.'s Cygnus spacecraft to the International

Space Station after a launch accident in October 2014.

Here are Space.com's major missions to keep an eye out for next year:

XCOR Aerospace and the Lynx space plane: Through 2015

XCOR Aerospace — the company building the Lynx space plane — has been making steady progress with the

Lynx for the last few years. The plane is designed to take commercial customers and science payloads on

flights to suborbital space. Lynx has room for one pilot and one passenger (as well as scientific experiments)

on each flight, which reaches 330,000 feet (100 kilometers) into the air.

SpaceX reusable rocket landing on ocean platform: No earlier than Jan. 6

The private spaceflight company SpaceX is planning to land the first stage of a Falcon 9 rocket on a floating

platform in the Atlantic Ocean no earlier than Jan. 6, after launching an uncrewed Dragon cargo capsule to the

International Space Station. This will mark the first time anyone has ever attempted this kind of reusable

rocket test, SpaceX representatives have said. SpaceX is also planning three more cargo launches in 2015

under a contract with NASA.

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DSCOVR satellite launching to space: No earlier than Jan. 29

The Deep Space Climate Observatory (DSCOVR) is set for launch on SpaceX's Falcon 9 rocket on Jan. 23. The

satellite is designed to monitor solar wind from about 900,000 miles (1.5 million kilometers) from Earth. The

DSCOVR mission is a partnership among NOAA, NASA and the U.S. Air Force, and some version of the mission

has been in process for more than 10 years.

Europe's IXV space plane prototype test flight: Feb. 11

Europe is due to launch a test flight of its reusable Intermediate eXperimental Vehicle (IXV) on Feb. 11. The

spacecraft is designed to make it back through Earth's atmosphere safely after flying to space. The European

Space Agency currently launches spacecraft to the International Space Station to deliver cargo; however,

those robotic craft burn up harmlessly as they come back through Earth's atmosphere. The IXV could allow

officials to bring experiments and other materials down from the space station safely. (SpaceX's Dragon

capsule already offers this capability.)

MESSENGER mission at Mercury ends: March or thereabouts

NASA's MESSENGER mission — currently orbiting Mercury — is expected come to an end by about March with

a planned impact into the closest planet to the sun. (The probe launched to space in 2004.) In December,

MESSENGER mission scientists announced that while the orbiter is out of fuel, the team had found a way to

use the probe's pressurant — used to pressurize fuel — to keep it in orbit longer, possibly up to another

month. During its time orbiting Mercury, MESSENGER (short for MErcury Surface, Space ENvironment,

GEochemistry and Ranging) has helped scientists snap pictures and craft the best map ever made of the

planet. The long-lived spacecraft also helped NASA confirm that Mercury does harbor water ice.

NASA's Dawn spacecraft arrives at Ceres: March 6

NASA's Dawn probe — which orbited the giant asteroid Vesta from July 2011 to September 2012 — is

expected to start circling another target, the dwarf planet Ceres, on March 6. The space agency wants to get

an up-close view of Ceres partially because it is the biggest object in the asteroid belt between Mars and

Jupiter. Some scientists even think Ceres could be a favorable place for life in the solar system.

Astronaut, cosmonaut launch on one-year mission: March 27

NASA astronaut Scott Kelly and cosmonaut Mikhail Kornienko are scheduled to launch to the International

Space Station for a one-year stay in space on March 27. This will mark the first time an American has ever

spent a continuous year in space, and it is the first-ever mission of this length attempted on the space station.

Usually missions to the orbiting outpost last about six months.

The Hubble Space Telescope turns 25: April 2015

The Hubble Space Telescope is about to turn 25 years old. The giant telescope launched to space aboard the

space shuttle Discovery in 1990. Hubble has gone through a variety of repairs, but it is still beaming back

amazing views of the universe from space. Scientists are expecting it to continue functioning through at least

2018, when its successor, the James Webb Space Telescope is scheduled to launch.

X-37B space plane launches on 4th secret mission: May 2015

The U.S. Air Force's secretive X-37B robotic space plane is expected to launch on its fourth mission sometime

in May. The space plane recently came back from a nearly two-year mission, landing in California on Oct. 17,

2014, after launching to space in December 2012. It's still not clear what X-37B's missions are designed to do;

information surrounding the vehicle's missions (including what it brings to orbit) is classified.

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New Horizons spacecraft flies by Pluto: July 14

NASA's New Horizons spacecraft will make its much-anticipated flyby of the dwarf planet Pluto on July 14. The

probe will start making observations of the relatively small cosmic body in January, but it will get its best look

at Pluto during the flyby. The spacecraft launched toward Pluto's distant part of the solar system in 2006.

Once it passes Pluto, the probe could fly by another frigid, faraway object during an extended mission (if NASA

approves the plan).

Rosetta spacecraft makes closest approach to sun with comet: August 2015

The European Space Agency's Rosetta spacecraft will accompany Comet 67P/ Churyumov-Gerasimenko on its

closest approach to the sun in August. Rosetta will monitor the way the comet changes as it gets closer to the

star, beaming back unprecedented science as it goes. ESA officials are also hoping that the Philae lander,

currently hibernating on Comet 67P/C-G, will wake up in the early months of 2015 and continue gathering

data. The Rosetta mission marks the first time humans have ever put a spacecraft in orbit around a comet,

and Philae is also the first probe to soft-land on a comet.

Curiosity's 3rd anniversary on Mars: Aug. 5

NASA's Curiosity rover will celebrate its third anniversary on the planet Mars on Aug. 5. The 1-ton robot has

already discovered some incredible things about the Red Planet during its time on the Martian surface.

Curiosity measured methane in Mars' atmosphere for the first time, a finding that could have implications for

whether life existed (or still exists) on the planet. The rover will continue exploring the base of Mt. Sharp, its

destination in Gale Crater, throughout 2015.

Japanese Akatsuki spacecraft may enter Venus' orbit: November 2015

After missing its chance to enter into orbit around Venus in December 2010, Japan's Akatsuki spacecraft will

have another chance to make it into orbit around the planet in November. The spacecraft missed its first

orbital opportunity when a key main-engine burn failed, but Japanese officials might be able to get it into orbit

in 2015 by using the probe's smaller thrusters to do the job. Akatsuki launched to space with the Ikaros solar

sail, which was the first successful demonstration of solar sail technology in space.

Cygnus rides to International Space Station again: Late 2015

The private spaceflight company Orbital Sciences Corp. has purchased space aboard United Launch Alliance's

Atlas V rocket to fly Orbital's robotic Cygnus spacecraft to the International Space Station in 2015 after a

rocket accident in October 2014. Cygnus cargo craft usually launch to the station via Orbital's Antares rocket,

but after an Antares carrying a Cygnus exploded just after liftoff, the rockets have been grounded by Orbital

until upgrades can be made. The first Atlas 5-carrying Cygnus should launch in late 2015.

Europe's LISA Pathfinder mission launching: 2015

The European Space Agency's LISA Pathfinder mission — designed as a technology demonstration to detect

ripples in space-time produced by the mergers of massive cosmic bodies — is expected to launch to space in

2015. If the probe does detect gravitational waves, it will be the first time a craft in space will have found

evidence of these giant cosmic crashes.

Source: Space.com Return to Contents

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3. Signs of Europa Plumes Remain Elusive in Search of Cassini Data

3.

Jupiter's icy moon Europa displays many signs of activity, including its fractured crust and a dearth of impact craters.

Scientists continue to hunt for confirmation of plume activity. Image Credit: NASA/JPL-Caltech/SETI Institute

A fresh look at data collected by NASA's Cassini spacecraft during its 2001 flyby of Jupiter shows that Europa’s

tenuous atmosphere is even thinner than previously thought and also suggests that the thin, hot gas around

the moon does not show evidence of plume activity occurring at the time of the flyby. The new research

provides a snapshot of Europa's state of activity at that time, and suggests that if there is plume activity, it is

likely intermittent.

The Europa results were being presented December 18th at the American Geophysical Union fall meeting in

San Francisco and published in the Astrophysical Journal. Europa is considered one of the most exciting

destinations in the solar system for future exploration because it shows strong indications of having an ocean

beneath its icy crust.

Members of Cassini's ultraviolet imaging spectrograph (UVIS) team analyzed data collected by their instrument

during the brief time it observed Europa in 2001, as Cassini sped through the Jupiter system enroute to

Saturn. The observations show that most of the hot, excited gas, or plasma, around Europa originates not

from the moon itself, but from volcanoes on the nearby moon Io. In fact, from their data, the researchers

calculated that Europa contributes 40 times less oxygen than previously thought to its surrounding

environment.

"Our work shows that researchers have been overestimating the density of Europa's atmosphere by quite a

bit," said Don Shemansky, a Cassini UVIS team member with Space Environment Technologies in Pasadena,

California, who led the study. The team found that the moon's tenuous atmosphere, which was already

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thought to be millions of times thinner than Earth’s atmosphere, is actually about 100 times less dense than

those previous estimates.

A downward revision in the amount of oxygen Europa pumps into the environment around Jupiter would make

it less likely that the moon is regularly venting plumes of water vapor high into orbit, especially at the time the

data was acquired.

Scientists would expect that ongoing plume activity at Europa, as Cassini has observed at Saturn's moon

Enceladus, would inject large amounts of water vapor into the area around Europa's orbit if the plumes were

large enough, but that is not what UVIS observed.

"We found no evidence for water near Europa, even though we have readily detected it as it erupts in the

plumes of Enceladus," said Larry Esposito, UVIS team lead at the University of Colorado at Boulder.

"It is certainly still possible that plume activity occurs, but that it is infrequent or the plumes are smaller than

we see at Enceladus," said Amanda Hendrix, a Cassini UVIS team member with the Planetary Science Institute

in Pasadena, who co-authored the new study. "If eruptive activity was occurring at the time of Cassini's flyby,

it was at a level too low to be detectable by UVIS."

Indications of possible plume activity were reported in 2013 by researchers using NASA's Hubble Space

Telescope, launching a wave of interest in searching for additional signs, including this effort by the UVIS

team. Cassini's 2001 Jupiter flyby provided UVIS the opportunity to directly measure the environment near

Europa, which is not possible with Hubble.

For more than a decade, Cassini's UVIS has observed the cold, dense doughnut of gas that encloses the orbit

of Enceladus. There, the massive amount of gas being breathed into orbit around Saturn by the Enceladus

plumes acts like a brake on electrons being dragged through it by Saturn's magnetic field, which rotates with

the planet. This braking helps to keep down the temperature of the plasma. Apparently there is no such brake

at Europa.

Since UVIS saw a hot plasma, rather than a cold one, around Europa's orbit, it suggests Europa is not

outputting large amounts of gas -- including water.

Snapshots provided by missions that visited Jupiter prior to Cassini provided strong indications that Io is the

major contributor of material to the environment around Jupiter, and indicated a hot, low density plasma

surrounding Europa. The new results confirm that. "Io is the real monster here," Shemansky said.

“Europa is a complex, amazing world, and understanding it is challenging given the limited observations we

have,” said Curt Niebur, Outer Planets program scientist at NASA Headquarters in Washington. “Studies like

this make the most of the data we have and help guide the kinds of science investigations NASA should pursue

in the future.”

Scientists are currently using the Hubble Space Telescope to conduct an extensive six-month long survey

looking for plume activity, and NASA is also studying various possible Europa missions for future exploration.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian

Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in

Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. JPL designed,

developed and assembled the Cassini orbiter. The UVIS team is based at the University of Colorado, Boulder,

where the instrument was designed and built.

Source: NASA Return to Contents

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The Night Sky

Source: Sky and Telescope Return to Contents

Tuesday, December 30

As Gemini rises into nice evening view, keep watch on

its red variable star R Geminorum: an unusual type-S

star with a weird mix of rare elements. It should be

about 9th magnitude now, on its way to a roughly

7th-magnitude maximum in February.

Wednesday, December 31

After the midnight cheering at the turning of 2015,

step outside into the silent dark. Look south. There

shines Sirius, the highest you'll see it. Upper right of it

stands Orion. Upper left of it is Procyon. Off your right

shoulder, the gibbous Moon hangs in the west. And

off your left shoulder, bright Jupiter dominates the

east.

Earlier this evening, Jupiter's moon Ganymede

disappears into eclipse by Jupiter's shadow at 10:18

p.m. EST. Europa follows Ganymede into Jupiter's

shadow at 11:00 p.m. EST, fading away more rapidly.

Keep watch as Mercury edges up closer to Venus day

by day this week and next.

Thursday, January 1

The waxing gibbous Moon shines in or near the

Hyades this evening. Late tonight the Moon's invisible

dark limb will occult (cover) Delta1 and/or Delta2

Tauri (magnitudes 3.8 and 4.8, respectively) for much

of the southern and western U.S.

Keep watch as Mercury edges up closer to Venus day by day this week and next.

Friday, January 2

This evening the Moon shines among some of the sky's brightest relatively cool stars. Look for orange-red Aldebaran (spectral type K5 III) to the Moon's upper right, similarly tinted Betelgeuse (type M2 Iab) a little farther below the Moon, and orange Pollux (type K0 III) much farther to the Moon's lower left. Bright Capella, yellow-white (type G5 III), shines high to the Moon's upper left.

Saturday, January 3

Are you tracking Venus and Mercury yet? They're now just 2½° apart, low in the afterglow of sunset, with brilliant Venus on top. Look southwest. They're drawing closer together; they will appear closest, just 0.6° apart, a week from today.

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ISS Sighting Opportunities (from Denver)

Not Available

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

NASA-TV Highlights (all times Eastern Time Zone)

Tuesday, December 30

9:55 a.m. - ISS Expedition 42 In-Flight Interviews with BBC Radio and the CBS News Radio Network

and Newspath Syndication Service (all channels)

Monday, January 5

12 p.m. - NASA ISS Earth Science Briefing: Cloud Aerosol Transport System (CATS) (all channels)

1:30 p.m. - NASA ISS Research and Technology Briefing (all channels)

4 p.m. - SpaceX Commercial Resupply Services (CRS) -5 Prelaunch News Conference (all channels)

Tuesday, January 6

4:30 a.m. - Video B-Roll Feed of SpaceX/Dragon CRS-5 Processing (all channels)

5 a.m. - Coverage of the Launch of the SpaceX/Dragon CRS-5 Cargo Ship to the ISS (Launch scheduled

at 6:18 a.m. ET) (all channels)

7:45 a.m.- SpaceX/Dragon CRS-5 Post-Launch News Conference – KSC (all channels)

9:15 a.m. - ISS Expedition 42 In-Flight Interviews with KGO-TV, San Francisco and the Associated

Press (all channels)

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

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Space Calendar

Dec 30 - EuropaSat Proton M-Briz M Launch

Dec 30 - Mercury Passes 3.7 Degrees From Venus

Dec 30 - Comet C/2014 R4 (Gibbs) Closest Approach To Earth (1.396 AU)

Dec 30 - Comet 16P/Brooks Closest Approach To Earth (1.538 AU)

Dec 30 - Comet 181P/Shoemaker-Levy Closest Approach To Earth (1.797 AU)

Dec 30 - Asteroid 25143 Itokawa Closest Approach To Earth (1.611 AU)

Dec 31 - Feng Yung 2G CZ-3A Launch

Dec 31 - Comet 110P/Hartley Closest Approach To Earth (1.494 AU)

Dec 31 - Comet C/2014 W7 (Christensen) Perihelion (1.510 AU)

Dec 31 - Asteroid 10 Hygiea At Opposition (10.0 Magnitude)

Dec 31 - Asteroid 6032 Nobel Closest Approach To Earth (1.897 AU)

Dec 31 - Asteroid 12757 Yangtze Closest Approach To Earth (2.065 AU)

Jan 01 - Comet 110P/Hartley At Opposition (1.494 AU)

Jan 01 - Comet 191P/McNaught At Opposition (1.705 AU)

Jan 01 - Comet 9P/Tempel At Opposition (3.112 AU)

Jan 01 - Kuiper Belt Object 230965 (2004 XA192) At Opposition (34.694 AU)

Jan 02 - Comet C/2014 Q2 (Lovejoy) At Opposition (0.488 AU)

Jan 02 - Comet C/2014 F2 (Tenagra) Perihelion (4.314 AU)

Jan 02 - Comet C/2014 W3 (PANSTARRS) Closest Approach To Earth (5.476 AU)

Jan 02 - Asteroid 4245 Nairc Occults HIP 19009 (5.5 Magnitude Star)

Jan 02 - Asteroid 2005 YQ96 Near-Earth Flyby (0.026 AU)

Jan 02 - Asteroid 18725 Atacama Closest Approach To Earth (1.445 AU)

Jan 02 - Asteroid 1981 Midas Closest Approach To Earth (2.210 AU)

Jan 03 - Quadrantids Meteor Shower Peak

Jan 03 - Comet 268P/Bernardi Closest Approach To Earth (1.618 AU)

Jan 03 - Comet 271P/van Houten-Lemmon Closest Approach To Earth (4.086 AU)

Jan 03 - Asteroid 241418 Darmstadt Closest Approach To Earth (2.019 AU)

Jan 04 - Earth At Perihelion (0.983 AU From Sun)

Jan 04 - Comet 37P/Forbes At Opposition (4.313 AU)

Jan 04 - Asteroid 9725 Wainscoat Closest Approach To Earth (1.834 AU)

Jan 04 - Asteroid 13681 Monty Python Closest Approach To Earth (2.212 AU)

Jan 05 - Mercury Passes 1.7 Degrees From Venus

Jan 05 - Comet P/2005 T2 (Christensen) At Opposition (3.821 AU)

Jan 05 - Asteroid 85990 (1999 JV6) Near-Earth Flyby (0.083 AU)

Jan 06 - CRS-5 Cloud-Aerosol Transport System (CATS)/ AggieSat 4/ Bevo 2/ SERPENS Falcon 9R Launch (International Space Station)

Source: JPL Space Calendar Return to Contents

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Food for Thought

What Does It Mean To Be ‘Star Stuff’?

The Tycho supernova remnant. This type of structure is all that remains after a massive star dies, releasing

the chemical building blocks of life and planetary systems into space. Credit: NASA/CXC/Chinese Academy of Sciences/F.

Lu et al.

At one time or another, all science enthusiasts have heard the late Carl Sagan’s infamous words: “We are

made of star stuff.” But what does that mean exactly? How could colossal balls of plasma, greedily burning

away their nuclear fuel in faraway time and space, play any part in spawning the vast complexity of

our Earthly world? How is it that “the nitrogen in our DNA, the calcium in our teeth, the iron in our blood, and

the carbon in our apple pies” could have been forged so offhandedly deep in the hearts of

these massive stellar giants?

Unsurprisingly, the story is both elegant and profoundly awe-inspiring. All stars come from humble

beginnings: namely, a gigantic, rotating clump of gas and dust. Gravity drives the cloud to condense as

it spins, swirling into an ever more tightly packed sphere of material. Eventually, the star-to-be becomes so

dense and hot that molecules of hydrogen in its core collide and fuse into new molecules of helium. These

nuclear reactions release powerful bursts of energy in the form of light. The gas shines brightly; a star is born.

The ultimate fate of our fledgling star depends on its mass. Smaller, lightweight stars burn though the

hydrogen in their core more slowly than heavier stars, shining somewhat more dimly but living far longer lives.

Over time, however, falling hydrogen levels at the center of the star cause fewer hydrogen fusion reactions;

fewer hydrogen fusion reactions mean less energy, and therefore less outward pressure.

At a certain point, the star can no longer maintain the tension its core had been sustaining against the mass of

its outer layers. Gravity tips the scale, and the outer layers begin to tumble inward on the core. But their

collapse heats things up, increasing the core pressure and reversing the process once again. A new hydrogen

burning shell is created just outside the core, reestablishing a buffer against the gravity of the star’s

surface layers.

While the core continues conducting lower-energy helium fusion reactions, the force of the new hydrogen

burning shell pushes on the star’s exterior, causing the outer layers to swell more and more. The star expands

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and cools into a red giant. Its outer layers will ultimately escape the pull of gravity altogether, floating off into

space and leaving behind a small, dead core – a white dwarf.

Heavier stars also occasionally falter in the fight between pressure and gravity, creating new shells of atoms to

fuse in the process; however, unlike smaller stars, their excess mass allows them to keep forming these

layers. The result is a series of concentric spheres, each shell containing heavier elements than the one

surrounding it. Hydrogen in the core gives rise to helium. Helium atoms fuse together to form carbon. Carbon

combines with helium to create oxygen, which fuses into neon, then magnesium, then silicon… all the way

across the periodic table to iron, where the chain ends. Such massive stars act like a furnace, driving these

reactions by way of sheer available energy.

But this energy is a finite resource. Once the star’s core becomes a solid ball of iron, it can no longer fuse

elements to create energy. As was the case for smaller stars, fewer energetic reactions in the core of

heavyweight stars mean less outward pressure against the force of gravity. The outer layers of the star will

then begin to collapse, hastening the pace of heavy element fusion and further reducing the amount of energy

available to hold up those outer layers. Density increases exponentially in the shrinking core, jamming

together protons and electrons so tightly that it becomes an entirely new entity: a neutron star.

At this point, the core cannot get any denser. The star’s massive outer shells – still tumbling inward and still

chock-full of volatile elements – no longer have anywhere to go. They slam into the core like a speeding oil rig

crashing into a brick wall, and erupt into a monstrous explosion: a supernova. The extraordinary energies

generated during this blast finally allow the fusion of elements even heavier than iron, from cobalt all the way

to uranium.

The energetic shock wave produced by the supernova moves out into the cosmos, disbursing heavy elements

in its wake. These atoms can later be incorporated into planetary systems like our own. Given the right

conditions – for instance, an appropriately stable star and a position within its Habitable Zone – these

elements provide the building blocks for complex life.

Today, our everyday lives are made possible by these very atoms, forged long ago in the life and death throes

of massive stars. Our ability to do anything at all – wake up from a deep sleep, enjoy a delicious meal, drive a

car, write a sentence, add and subtract, solve a problem, call a friend, laugh, cry, sing, dance, run, jump, and

play – is governed mostly by the behavior of tiny chains of hydrogen combined with heavier elements like

carbon, nitrogen, oxygen, and phosphorus.

Other heavy elements are present in smaller quantities in the body, but are nonetheless just as vital to proper

functioning. For instance, calcium, fluorine, magnesium, and silicon work alongside phosphorus to strengthen

and grow our bones and teeth; ionized sodium, potassium, and chlorine play a vital role in maintaining the

body’s fluid balance and electrical activity; and iron comprises the key portion of hemoglobin, the protein

that equips our red blood cells with the ability to deliver the oxygen we inhale to the rest of our body.

So, the next time you are having a bad day, try this: close your eyes, take a deep breath, and contemplate the

chain of events that connects your body and mind to a place billions of light-years away, deep in the distant

reaches of space and time. Recall that massive stars, many times larger than our sun, spent millions of

years turning energy into matter, creating the atoms that make up every part of you, the Earth, and everyone

you have ever known and loved.

We human beings are so small; and yet, the delicate dance of molecules made from this star stuff gives rise to

a biology that enables us to ponder our wider Universe and how we came to exist at all. Carl Sagan himself

explained it best: “Some part of our being knows this is where we came from. We long to return; and we can,

because the cosmos is also within us. We’re made of star stuff. We are a way for the cosmos to know itself.”

Source: Universe Today Return to Contents

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Space Image of the Week

Galactic Get-Together Has Impressive Light Display

Image Credit: X-ray: NASA/CXC/SAO/S.Mineo et al, Optical: NASA/STScI, Infr

At this time of year, there are lots of gatherings often decorated with festive lights. When galaxies get

together, there is the chance of a spectacular light show as is the case with NGC 2207 and IC 2163

Located about 130 million light years from Earth, in the constellation of Canis Major, this pair of spiral galaxies

has been caught in a grazing encounter. NGC 2207 and IC 2163 have hosted three supernova explosions in

the past 15 years and have produced one of the most bountiful collections of super bright X-ray lights known.

These special objects – known as “ultraluminous X-ray sources” (ULXs) – have been found using data from

NASA’s Chandra X-ray Observatory.

As in our Milky Way galaxy, NGC 2207 and IC 2163 are sprinkled with many star systems known as X-ray

binaries, which consist of a star in a tight orbit around either a neutron star or a “stellar-mass” black hole. The

strong gravity of the neutron star or black hole pulls matter from the companion star. As this matter falls

toward the neutron star or black hole, it is heated to millions of degrees and generates X-rays.

ULXs have far brighter X-rays than most “normal” X-ray binaries. The true nature of ULXs is still debated, but

they are likely a peculiar type of X-ray binary. The black holes in some ULXs may be heavier than stellar mass

black holes and could represent a hypothesized, but as yet unconfirmed, intermediate-mass category of black

holes.

This composite image of NGC 2207 and IC 2163 contains Chandra data in pink, optical light data from the

Hubble Space Telescope in red, green, and blue (appearing as blue, white, orange, and brown), and infrared

data from the Spitzer Space Telescope in red.

Source: NASA Return to Contents