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