Popular Science - USA (2020 - Winter)

TALES FROM THEFIELD

MARIA PIA MIGLIETTA,PROFESSOR OF MARINE

BIOLOGY AT TEXAS A&M UNIVERSITY AT GALVESTON

In my youth, on the shores of

southern Italy, I’d constantly play

with Turritopsis dohrnii, a tiny jellyfish

discovered in the Mediterranean Sea

in 1883. Today you can find the species

all over the world’s oceans because

they reproduce like crazy—and it’s no

exaggeration to say they live forever.

When T. dohrnii reaches mature size,

it can curl into a tiny ball and split itself

into a colony of newborns, sometimes

as many as hundreds of baby jellies. In

this process, called trans dif fer en tiation,

adult cells reconfigure themselves into

new ones. Uncovering how this change

My team and I have been sequenc-

ing the adult’s genes, looking at which

ones control the transdifferentiation

process and how exactly they pull it

off. We’ve found that in addition to

loads of cellular repair, the jellyfish

also prevent their telomeres— caps at

the ends of DNA strands that protect

against aging— from shortening, as

they do in almost all other species on

the planet. We believe that this could

be key to keeping cells young.

Next, I want to pinpoint why this jelly

can cheat death, while its nearly identi-

cal sister species (T.  nutricula) still

succumbs to old age. I want to find and

study those life-altering genes.

By the time the Opportunity and

Spirit rovers touched down on

Mars in January 2004, my colleagues

and I were already pondering new proj-

ects. We’d designed the pair of rovers

knowing that the Red Planet is a gritty

place. We weren’t sure exactly when

Mars’ infamous dust clouds would coat

their solar panels and block out the sun,

rendering them powerless.

We planned for roughly 90 days of

exploration, but no one told the rovers.

Spirit traipsed the sandy plains for about

six years, and Opportunity kept going for

around 14. Our lucky streak started right

away: Mars gave us what we called

“cleaning events”—gentle winds that un-

expectedly dusted off the rovers and

boosted power production. Because the

planet receives adequate sunlight, the

solar panels we’d expected to fail actu-

ally gave a nearly infinite energy source.

Fortunately, expecting a short mission

hadn’t stopped designers from picking

the most reliable components. Even after

14 years, most of Opportunity’s motors

could have lasted for at least another

decade. And when parts did act up, we

thought creatively. After a heater’s

switch got stuck in the on position, for

instance, our team reworked Opportu-

nity’s standard bedtime routine to

force nonessential systems to shut

down, which switched off the faulty

part and saved needed power.

The team felt devoted to the rovers—

like they were friends, pets, or even

family members. We did whatever we

could to keep them going. Ultimately, a

spill into a sand trap hobbled Spirit in

year six. If not for a Martian dust storm—

the thickest we’ve ever seen—blotting

out the sun in year 14, Opportunity

might still be rolling along as usual.

The current generation of rovers,

Curiosity and Perseverance, run on nu-

clear power and have more backup

parts. That’s largely because Opportu-

nity and Spirit proved we could operate

for far longer than 90 days, empower-

ing mission designers to start planning

expeditions that last for years.

the little rovers

that could

as told to Charlie Wood

MATT KEUNEKE, MARS EXPLORATION ROVER
MISSION OPERATIONS MANAGER AT NASA

118 WINTER 2020 / POPSCI.COM

as told to Sara Kiley Watson