Astronomy - 06.2019

ASTRONEWS

10 ASTRONOMY • JUNE 2019

One of InSight’s instruments is stuck

in the ground; engineering models

on Earth could solve the problem.

N

ASA’s Mars InSight lander touched

down in November and immediately

got to work studying Mars’ deep

interior, including what it’s made of

and how the planet’s layers move. InSight

spent months studying the area around its

landing site, practicing its movements and

scouting the best locations to place instru-

ments. Then, in late February, it started

digging — and promptly got stuck.

ABRUPT STOP

InSight’s Heat Flow and Physical Properties

Package (HP^3 ) instrument includes a “mole”

— a self-hammering spike — designed to

burrow up to 16 feet (5 meters) underground.

But the mole made it only about a foot

(0.3 m) deep before stopping. In March, HP^3

principal investigator Tilman Spohn told

Astronomy the team’s best guess was that the

mole hit a rock or a gravel layer shortly after

beginning to dig February 28.

To find out more, the NASA team

turned to InSight’s camera and other sen-

sors. They also set to work on re-creating

the problem with engineering models on

Earth: InSight has a twin in Berlin, and

copies of its various instruments, including

the mole, also exist. Any potential solutions

will be tested extensively using the models

on Earth before trying them on the real

InSight on Mars.

But some scenarios might stop the

$800 million mission where it stands. “If it’s

a 1-meter (3 feet) block of rock at the spot,

there’s no way we can handle that situation,”

Spohn says. “The hope is that what we’re

hammering against is a small rock, say half

the size of the mole’s length. We could push

that aside by continuing to hammer.” Spohn

calls this the “brute force” approach.

One possible tactic would be to press

down on the mole or its support structure,

probably with InSight’s arm, lending the

mole more force and limiting recoil. But the

arm wasn’t designed for such a move. “If

you make a mistake, it’s gone,” Spohn says.

But he also points out that if the mole is

able to dig freely again, it could reach its

target depth within about four hours.

InSight has plenty of power to finish the

dig, as the lander runs on solar power and

was designed for two Earth years of duty.

STILL GOOD SCIENCE

The mole needs to descend at least 10 feet

(3 m) to measure heat flow from Mars’

interior. If it can’t continue, “we would lose

a significant amount of science,” Spohn

admits. But InSight’s other instruments are

working as planned, and NASA could still

get information from the dirt InSight has

already dug through. “It would still be stuff

that hasn’t been done before,” Spohn says.

“Not as bold as originally planned, but still

good science.” — Korey Haynes

MARS LANDER DIGS IN, THEN GRINDS TO A HALT

SYSTEMS GO. NASA plans to launch the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices

Explorer, or SPHEREx, in 2023 to observe the entire sky in almost 100 different wavelengths and illuminate the origins of the universe.

SITTING PRETTY. The HP^3 instrument sits on the martian surface in this image taken March 19 by InSight’s

Instrument Deployment Camera. NASA is trying to find out why a hammering spike on HP^3 has stopped digging.

NASA/JPL-CALTECH

Summer storms on Uranus and Neptune

CLOUDY SKIES. Astronomers use the Hubble

Space Telescope to check on our outer solar system

neighbors annually. These images, taken in September

and November 2018, show weather on the ice giants.

At right, a dark storm spanning about 6,800 miles

(11,000 kilometers) rages on Neptune. It is the fourth

such tempest Hubble has imaged on the planet

since 1993. To the right of the dark vortex are white

companion clouds, which form as methane gas is

thrust upward by the storm’s vortex and freezes into

clouds. On the left is Uranus, with a large, white cloud

over its north polar cap. Researchers believe the

cloud is a result of the planet’s unique rotation and

tilt, which expose the north pole to uninterrupted

sunlight during the long summer season. Astronomers

aren’t sure how the narrow band of clouds around

the equator formed. Charting the weather on these

two ice giants helps scientists better understand the

differences — and similarities — between the planets

that share our Sun. — Alison Klesman NASA, ESA, A. SIMON (NASA GODDARD SPACE FLIGHT CENTER), AND M.H. WONG AND A. HSU (UNIVERSITY OF CALIFORNIA, BERKELEY)