Astronomy - February 2014

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Despite previous reports that the martian

atmosphere was home to methane, NASA’s

Curiosity rover failed to detect such mole-

cules. The chemical, composed of four

hydrogen atoms and one carbon atom, is of

special interest to scientists because metab-

olizing microbes sometimes produce it.

Although not slam-dunk evidence, the pres-

ence of methane could have hinted at life on

the Red Planet.

Curiosity sampled Mars’ atmosphere six

times between October 2012 and June 2013,

and analysis revealed that if methane is

there, it must be less than 1.3 parts per bil-

lion. Other missions — either in orbit around

Earth or Mars — had reported pockets of up

to 45 parts per billion, but Curiosity is newer,

more sensitive, and on the ground. Its

results, therefore, trump others’ prior work.

This result, published in the October 18

issue of Science, does not quite put a nail in

the microbes’ coffin. “It reduces the probabil-

ity of current methane-producing martian

microbes,” says Michael Meyer, NASA’s lead

scientist for Mars exploration, “but this

addresses only one type of microbial metab-

olism. As we know, there are many types of

terrestrial microbes that don’t generate

methane.” — S. S.

QUICK TAKES

MAVEN TO MARS

NASA’s Mars Atmosphere and

Volatile Evolution (MAVEN)

spacecraft launched Novem-

ber 18 at 1:28 P.M. EST.

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LIGHT TANTRUM

An October Astronomy &

Astrophysics paper describes

X-ray observations of gas

clouds 30 to 100 light-years

from the Milky Way’s super-

massive black hole, which

suggest the region became a

million times brighter during

outbursts in the past few

hundred years.

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JOVIAN JOURNEY

NASA’s Juno spacecraft

entered safe mode October

9 as it flew by Earth for a

gravity boost on its way to

Jupiter. Two days later, the

craft was fully operational

and all systems functional.

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IN MEMORIAM

George H. Herbig, known for

his important research on

star formation, died October

12 at the age of 93.

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COMET PIECE

A black pebble found years

ago in the Sahara is a frag-

ment of a comet nucleus

that exploded in Earth’s

atmosphere some 28 million

years ago, say scientists in

the November 15 Earth and

Planetary Science Letters.

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FAST WORLDS

Researchers found six likely

exoplanets that orbit their

stars in fewer than 12 hours.

They presented their finding

October 8 at the Division for

Planetary Sciences meeting.

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CLOUD CHAMBER

A study in the September

issue of the Journal of Geo-

physical Research: Planets

describes how scientists re-

created Mars-like tempera-

ture and humidity conditions

and found that martian

clouds required 190 percent

of the chamber’s relative

humidity to form.

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HOT STUFF

Astronomers discovered an

unexpected cloud of glow-

ing hot “ionized” hydrogen

gas around the red supergi-

ant star W26. They published

their finding online October

16 in the Monthly Notices of

the Royal Astronomical Soci-

ety Letters. — Liz Kruesi

Curiosity smells no

methane on Mars

While studying the debris disks around

stellar remnant white dwarfs, astrono-

mers came across two ingredients

for habitable worlds no scientist had

previously found together: water and

a rocky surface. What they uncov-

ered was the shattered remains of an

asteroid composed of 26 percent water

by mass that likely was once at least 55

miles (90 kilometers) in diameter. The

scientists report their findings in the

October 11 issue of Science.

White dwarfs provide an excellent

laboratory for studying the composition

of the building blocks of solar systems

beyond our own. The only way to see

what distant planets or asteroids are

made of is to break them apart, and

a white dwarf ’s extreme gravitational

pull on nearby worlds does just that.

In the case of the white dwarf GD 61,

its shredding revealed that parts of its

planetary system survived its transition

from a star somewhat larger than the

Sun, and this debris had water amounts

similar to those found on Ceres, the

largest asteroid in our solar system.

“This planetary graveyard swirling

around the embers of its parent star

is a rich source of information about

its former life,” says co-author Boris

Gänsicke of the University of Warwick.

“In these remnants lie chemical clues

which point towards a previous exis-

tence as a water-rich terrestrial body.”

Adds lead author Jay Farihi of the

University of Cambridge’s Institute of

Astronomy: “The finding of water in

a large asteroid means the building

blocks of habitable planets existed

— and may still exist — in the GD 61

system and likely also around a sub-

stantial number of similar parent stars.”

— Karri Ferron

Water found in exoplanet remnants

Null result. The Curiosity rover, which has been on Mars for more than a year,

failed to detect methane, a chemical that could have been a sign of microbial life.

Water-rich remNaNts. Scientists have discovered the remnants of a rocky, water-rich

asteroid that was torn apart by the strong gravity of its white dwarf parent star, as this illus-

tration portrays. MARk A. GARliCk (SPACE-ART.CO.uk)/uNiV. Of WARWiCk/uNiV. Of CAMbRiDGE

NASA/JPl-CAlTECH/MAliN SPACE SCiENCE SySTEMS

Curiosity’s older sibling, the Oppor-

tunity rover, has been exploring the

Red Planet for a decade.

FAST

FACT