The Economist - USA (2019-12-21)

The EconomistDecember 21st 2019 Science & technology 119

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without detailed instructions from Earth.

Once the fetch rover has collected all the

tubes, it will deliver the rack to a nasa-built

craft called the Mars Ascent Vehicle (mav).

This rocket will have arrived from Earth,

filled with fuel, in the same mission as the

fetch rover. Once it has the samples, it will

launch itself from the surface of Mars—the

first ever rocket launch from a planet other

than Earth.

Once in orbit, the mavwill throw its

basketball-sized payload overboard. Wait-

ing nearby to intercept the cargo will be yet

another craft, the Earth Return Orbiter

(ero), built by esa. This will have been

launched from Earth independently of the

mav-and-fetch-rover mission. The ero

will find, ingest and seal the payload, to

avoid contaminating it with any organisms

that might have hitched a ride all the way

from Earth. Using a gentle, solar-powered

electric propulsion system, the erowill

then take the payload back to Earth over the

course of the subsequent few years.

When the eroeventually goes into orbit

around Earth (which will be in 2031, at the

earliest) it will release the payload. This

will be packed into a special, dome-shaped

Earth Return Vehicle designed to carry the

samples safely through the ferocity of at-

mospheric re-entry to a landing in the des-

ert of Utah—whence they will be taken to

their new bio-fortified home for examina-

tion. Once examined and deemed safe, the

samples will then be distributed to re-

searchers around the world for study.

Lakeside view

It is, then, an extraordinary enterprise. But

all of this complexity does raise the ques-

tion of why researchers would go to so

much effort to collect Mars rocks. The an-

swer, as Michael Meyer, the scientific boss

of nasa’s Mars Exploration Programme,

told the conference, is that although, when

you are on another planet, you have to

hand all the rocks that you could ever want,

you are also stuck with the handful of in-

struments that you took with you to look at

them. Using sophisticated X-ray scanners

or grinding samples up and feeding them

through a chemistry set is not an option.

It is true that Martian rocks are already

available for study, in the form of 200 or so

meteorites that have arrived on Earth after

having been blasted from the Martian sur-

face by asteroid impacts. However, though

these are geologically valuable they have

little to offer about any putative Martian bi-

ology because they have spent millions of

years travelling through the harsh condi-

tions of space, being bombarded by radia-

tion that will probably have destroyed any

complex molecules within them that were

made by living things.

A sample-return mission will not be

cheap. Researchers from nasa and esa,

who have established a working group to

harmonisetechnicaleffortsforthevarious

stagesoftheproject,estimateitwillcost

$7bntocomplete.esaalreadyhasapproval

forsomeofitsparts.Whenministersfrom

its 22 membercountriesmetinNovember

to discuss the agency’s next three-year

budget, they agreed to make €450m

($500m)availabletopayfortheproject’s

earlystages.Foritspart,nasaexpectsto

hearaboutfunding formsrinFebruary

2020,aspartofnextyear’sfederalbudget.

nasaneedstoconfirmitsroleinthe

projectassoonaspossibleiftheplanned

timetableistobemet.If it isbegunandnot

ended,though—perhapsbecausethemon-

eyrunsouthalfwaythrough—participants

willhavethecomfortthatthebottled-up

samplesarereadyandwaitingforcollec-

tionwheneveritisthatpoliticianschoose

toloosentheappropriatepursestrings. 7

T

he differentparts of a health-care

system have different focuses. A hospi-

tal’s dementia unit keeps records of pa-

tients’ mental abilities. The stroke unit

monitors blood flow in the brain. The car-

diac unit is interested in that same flow,

but through and from the heart. Each ag-

glomeration of equipment and data is ef-

fective in its own domain, but for the most

part has little relevance to other bits of the

body and the conditions that plague them.

Thus, like the proverbial blind men feeling

an elephant, modern health care offers

many fragmented pictures of a patient, but

rarely a useful cohesive one.

On top of all this, the instruments that

doctors use to monitor health are often ex-

pensive, as is the training required to wield

them. That combined cost is too high for

the medical system to scan regularly, for

early signs of illness, all patients at risk of

dementia, heart disease or a stroke. Rather,

doctors work to manage symptoms after a

disease has obviously taken hold.

An unusual research project called Alz-

Eye, run from Moorfields Eye Hospital in

London, in collaboration with University

College, London (ucl), may change this. It

is attempting to use the eye as a window

through which to detect signals about the

health of other organs. The doctors in

charge of it, Siegfried Wagner and Pearse

Keane, are linking Moorfields’ database of

eye scans, which offer a detailed picture of

the health of the retina, with information

about other aspects of its patients’ health

garnered from other hospitals around Eng-

land. This will allow them to look for tell-

tales of disease in the eye scans.

The data set includes, whether they

know it or not, every one of the 300,000 pa-

tients who visited Moorfields between

2008 and 2018 and was over the age of 40—

though names and other easily identifiable

information are not preserved. The idea is

to examine changes to people’s eyes within

that ten-year period, and correlate these

with, say, the emergence of Alzheimer’s

disease in the same patient. Building such

a data set while respecting privacy and con-

fidentiality has been a challenge. It took

the doctors two and a half years to go

through a series of ethics-committee ap-

provals at Moorfields, ucland nhsDigital,

the body which handles agglomerated data

from English hospitals. In order to create

the database without the consent of the pa-

tients involved they invoked a special legal

provision known as Section 251 assent,

which comes with its own review process

and, in essence, empowers senior govern-

ment health officials to give consent on be-

half of patients from whom it would be im-

practical or impossible to acquire such

individually. The data sets were linked to-

gether on November 1st, and the process of

correlation is now under way.

The Moorfields data set has a lot of

linked cases to work with—far more than

any similar project. For instance, the uk

Biobank, one of the world’s leading collec-

tions of medical data about individual peo-

ple, contains 631 cases of a “major cardiac

adverse event”. The Moorfields data con-

tain about 12,000 such. The Biobank has

data on about 1,500 stroke patients. Moor-

fields has 11,900. For the disease on which

the Moorfields project will focus to start

with, dementia, the data set holds 15,100

cases. The only comparable study had 86.

Drs Wagner and Keane are searching for

patterns in the eye that betray the emer-

gence of disease elsewhere in the body, and

are focusing first, as the name AlzEye sug-

gests, on Alzheimer’s disease. They will

A system based on aiwill search the

retina for early signs of disease

Medical diagnosis

iScanning

Keeper of secrets