Astronomy – October 2019

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24 ASTRONOMY • OCTOBER 2019

rover’s landing ellipse, which spanned

just 12 by 4 miles (20 by 7 km).

Thus, the InSight team wanted the

spacecraft to land in a big, flat, rock-free,

sand-free, low-dust parking lot. Indeed,

it was almost the exact opposite of what

most planetary geologists seek — exotic

minerals, sedimentary layers, hills, val-

leys, water-related landforms — when

they want to land on Mars. Luckily for

the InSight team, Mars has an abun-

dance of f lat, relatively boring places.

One particular site — in Elysium Planitia

near 4.5° north latitude and 135.0° east

longitude — also satisfied the mission’s

additional requirements: a low elevation

for the parachute to work well and an

equatorial region so the mission could

operate under solar power.

After a speedy and relatively unevent-

ful six-and-a-half-month cruise to Mars,

InSight team members and millions fol-

lowing online experienced their own

“seven minutes of terror” as the space-

craft autonomously executed its carefully

choreographed set of entry, descent, and

landing activities November 26, 2018.

Scientists on the ground monitored

many of these activities in near-real

time, delayed only by the eight-minute

light travel time from Mars, as the

lander relayed its radio signals back

to Earth through two CubeSats. These

small satellites, each about the size of a

cereal box, had been launched with the

main spacecraft back in May. Called

Mars Cube One (MarCO) A and B and

nicknamed Eve and Wall-E by their JPL

engineering creators, the satellites did

their job perfectly. They relayed telem-

etry and eventually the first dusty

InSight photos from the surface as they

sped past Mars, performing f lawlessly

The lander’s Temperature and Winds for InSight (TWINS) meteorology

package has been producing daily weather reports from the martian
surface since February 19. The instrument takes temperature, wind

speed and direction, and atmospheric pressure measurements every

second, then downloads the data to Earth every martian day, or sol.
To see the daily weather report from Mars, visit https://mars.nasa.gov/

insight/weather. The site gives the high, low, and average temperatures

(in both Fahrenheit and Celsius) and pressures in pascals (1,000 pascals

equals 0.01 bar, or about one-hundredth of the atmospheric pressure at

Earth’s surface). The station reports wind speed in both miles per hour

and meters per second and gives the most common direction of the wind

that day. In the three-day plots the website provides, the wind directions

appear as barbs extending from the speed data point, with due south

angled straight down and due east to the right. — Richard Talcott

BABY, IT’S COLD OUTSIDE

InSight’s robotic arm places its copper-colored

seismometer onto Mars’ surface December 19, 2018.

The seismometer records seismic rumbles caused

by marsquakes and nearby meteorite strikes.

The dome-shaped Wind and Thermal Shield covers

InSight’s seismometer. The shield protects the

sensitive seismometer from background noise that

could drown out the weak seismic whispers it seeks.

The weather on Mars has been chilly since InSight landed. In late June, the temperature averaged

around –94 degrees Fahrenheit (–70 degrees Celsius), with daytime highs rising to near –12 F (–24 C)

and nighttime lows plummeting to –154 F (–103 C). InSight’s meteorology station provides daily

updates of the temperature, wind, and surface pressure in Elysium Planitia. NASA/JPL-CALTECH/CORNELL/CAB