2019-06-01+Sky+and+Telescope

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skyandtelescope.com • JUNE 2019 11


SPACE MISSIONS
Israeli Lander Launches
for the Moon
A SPACEX FALCON 9 ROCKET car-
ried the lunar lander Beresheet (“in the
beginning” in Hebrew) to space on Feb-
ruary 21st. It’s headed for a soft landing
on the Moon in mid-April.
The privately funded lander, built
by Israeli company SpaceIL, was a
secondary payload accompanying an
Indonesian communications satellite
and a U.S. Air Force satellite. All three
were placed in geostationary orbit, but
that only takes Beresheet about a tenth
of the way to the Moon. The lander
must propel itself the rest of the way by
slingshotting around Earth in increas-
ingly elongated orbits. After a seven-
week journey, the mission will target a
landing in the northern part of Mare
Serenitatis (“Sea of Serenity”).
SpaceIL and its Beresheet lander were
born from the Google Lunar XPRIZE,

Earth Beresheet’s path

Moon

sending more than a thousand recovery
commands, but to no avail.
About 14½ years ago, Opportunity
bounced to a landing inside Eagle Crater
on January 25, 2004, ultimately travers-
ing 45.16 km (28.06 miles). Its record-
breaking journey broke new ground in
both exploration and planetary geology.
The rover was the fi rst mission to
identify and characterize a sedimen-
tary rock record on a world other than
Earth. The layers of sulfate-rich sand-
stone it discovered pointed to a wet past
for the Red Planet. But as Steve Squyres
(Cornell University) noted, “It wasn’t
‘water on Mars, water on Mars!’ It was
really ‘sulfuric acid on Mars.’”

In 2008, Opportunity embarked on
what was essentially a second mission.
Driving 21 kilometers over three years
to Endeavour Crater, the rover arrived
to fi nd older rocks along the crater’s rim
that were laden with clay minerals. This
evidence suggested Mars went through
an earlier era when the water coursing
through its rocks had been fi t to drink.
The end of the Opportunity mission
leaves Curiosity as the sole rover on
Mars, but it should soon have company:
NASA’s Mars 2020 rover and the Euro-
pean Space Agency’s Rosalind Franklin
rover are due to head to the Red Planet
during next year’s launch window.
■ DAVID DICKINSON

which challenged teams to land on and
explore the Moon. The competition’s
March 31, 2018, deadline for $30 mil-
lion has passed, so SpaceIL won’t win
any money. Still, the team did well for
itself, raising $100 million to fund the
lander from the Israeli Space Agency
and private donors.
The solar-powered lander is expected
to last 2 to 3 days on the lunar surface.
Although it’s primarily a technol-
ogy demonstrator, Beresheet carries a
small science package equipped with an
instrument to measure magnetism in
Moon rocks, as well as a laser retrore-
fl ector contributed by NASA and several
cameras. Beresheet also bears a small
time capsule, including a 30 million-
page archive of human history and
civilization encoded on nickel discs.
If the mission is successful, Israel
will become the fourth nation — behind
the United States, Russia, and China —
to make a soft landing on the Moon.
■ DAVID DICKINSON

IN BRIEF


A First Wave of
Transient Discoveries
The Zwicky Transient Facility (ZTF) is
now fully operational, scanning the entire
northern sky every three days. After fi rst
light in November 2017, the ZTF began
science operations in March 2018. Its fi rst
order, though, was to build an archive of
“reference images” for comparison against
new images; now that step is complete.
The ZTF has already identifi ed nearly
1,200 supernovae and 50 small near-Earth
asteroids, including two that zipped past
Earth at roughly a third of the distance to
the Moon. Another asteroid, 2019 AQ 3 ,
was discovered on January 4th with the
shortest known orbital period: It whips
around the Sun every 165 days, keeping
it within Venus’s orbit. The ZTF has also
observed more than a billion stars, spot-
ted new binary star systems, and caught
two star-shredding black holes in the act.
Many of these observations are detailed in
papers to appear in a special issue of the
Publications of the Astronomical Society
of the Pacifi c, but this wave of discoveries
is only a hint of what’s to come.
■ SHANNON HALL

Gravitational-Wave Alerts
from LIGO
Now that the Laser Interferometer Gravita-
tional-wave Observatory (LIGO) has 11 de-
tections under its metaphorical belt, the
team is prioritizing follow-up observations.
To that end, LIGO is making all gravitation-
al-wave detections public knowledge right
away during its third observing run (April
2019 – April 2020). As improvements have
been made to both the LIGO and Virgo
detectors in between observing runs, this
observing run should herald a period of
enhanced discovery. Scientists expect
at least a few black hole mergers every
month, as well as at least one neutron star
merger per year. The team will be distribut-
ing all gravitational-wave signals via the
Gamma-ray Coordinates Network (GCN).
Coordinates of new events will be distrib-
uted via GCN Notices, while announce-
ments of follow-up observations will come
in GCN Circulars. You can visit the GCN
website (https://gcn.gsfc.nasa.gov ) to
subscribe to Notices, Circulars, or both via
your email. Or, if you prefer to have an app
for that, citizen scientist Peter Kramer has
created Gravitational Wave Events for iOS.
■ MONICA YOUNG
Free download pdf