The Economist - USA (2020-11-21)

74 Science & technology The EconomistNovember 21st 2020

1

I

n january 2019, when a Chinese space-

craft called Chang’e 4visited the Moon,

the mission broke new ground, figuratively

speaking, by landing on the far side of that

orb, which is perpetually invisible from

Earth and thus also out of direct radio con-

tact. This meant communications had to

be relayed by a satellite which had been

cunningly located for the purpose at a

place where the interaction of the gravita-

tional fields of Earth and Moon meant it

could orbit a point in empty space.

China’s next lunar mission, by contrast,

will break ground literally. Chang’e 5,

scheduled for launch around November

24th, is intended to drill two metres down

into the Moon’s surface, retrieve about 2kg

of rock, and then return this to Earth. If

successful, it will be the first lunar sample-

return mission since 1976, when a Soviet

probe called Luna 24sent back a mere 170g

of the stuff. And it will be another step for-

ward in China’s space programme.

The Chang’e missions, named after a

Chinese Moon goddess, have had their ups

and downs. Chang’e 5was originally sched-

uled for blast off in 2017, but the failure in

July of that year of an otherwise-unrelated

project that was, like Chang’e 5, using a

Long March 5 as its launch vehicle, caused a

delay. (Chang’e 4used a different sort of

launcher, a Long March 3b.) The “go” does,

however, now seem to have been given.

State media reported on November 17th

that the rocket with Chang’e 5on board has

been moved to its launch pad at Wenchang

space centre, on Hainan island.

Assuming the launch goes to plan, suc-

cess will then depend on a complex ballet

involving the craft’s four components.

These are a service module, a return-to-

Earth module, a lunar lander and an as-

cender—a configuration originally used by

America’s Apollo project. Once the mission

is in lunar orbit, the lander and the ascend-

er will separate from the orbiting mother

ship of service and return modules as a sin-

gle unit and go down to the surface. The

landing site is in the northern part of a vast

expanse of basalt called Oceanus Procella-

rum, a previously unvisited area. Research-

ers hope rocks collected here will confirm

that volcanic activity on the Moon contin-

ued until far more recently than the 3.5bn

years ago that is the estimate derived from

studies of currently available samples.

Once the new material has been gath-

ered, which will take several days, the as-

cender will lift off, dock with the mother

ship and transfer its haul to the return

module. The service module will then carry

the return module back to Earth, releasing

it just before arrival to make a landing at a

recovery site in Inner Mongolia, also used

for China’s crewed missions, in December.

Digging into the lunar surface may,

however, pose problems. InSight, an Amer-

ican rover now on the surface of Mars, has

struggled to operate a drill nicknamed “the

mole” that is designed to reach three me-

tres below ground level. According to

nasa, America’s space agency, this is be-

cause the mole has encountered clumpier

regolith than its designers were expecting,

causing it to bounce rather than burrow.

If Chang’e 5does manage to overcome

such hazards and return samples to Earth,

China has said little so far about which for-

eign countries, if any, will be granted ac-

cess to them. But America is likely to be last

in the queue. For the past couple of decades

American governments of all stripes have

been reluctant to co-operate with China in

space-related matters, largely because of

fears about giving away secrets useful for

designing ballistic missiles. In space, as in

so much else, the two powers are not-so-

friendly rivals. China’s stated goal is to es-

tablish a crewed base near the Moon’s

south pole, where water is available in the

form of ice perpetually shielded from sun-

light by crater walls. America has similar

plans. Watch, as it were, this space. 7

BEIJING

China plans to bring back the first

Moon rocks for 40 years

Space exploration

Mandate of heaven

This picture shows the 5,000-year-old

aftermath of a merger between two

stars—though the light that created it

took a further 6,000 years to reach Earth’s

neighbourhood. It was published in this

week’s Natureby Keri Hoadley of the

California Institute of Technology and her

colleagues. It is a composite of three

images taken at different frequencies, two

by the Galaxy Evolution Explorer, a space

telescope which operated from 2003 to

2012, and one from the ground. The blue

area represents gas ejected during the

merger. The faint red rings are the visible

traces of shock waves from the resulting

explosion. Such collisions are reasonably

common in binary star systems. But this

image is reckoned one of the clearest so

far of the consequences.

When stars collide

W

aiting for a breakthrough in the

fight against covid-19 has been a bit

like waiting for a bus to arrive. After almost

a year of watch-checking and neck-cran-

ing, two come along at once. First, on No-

vember 9th, Pfizer, an American pharma

giant and BioNTech, a German minnow,

announced that they had jointly developed

an effective vaccine for the illness. They

were followed, on November 16th, by Mo-

derna, an American biotech firm.

Moderna says its offering is 94.5% ef-

fective. Pfizer says the efficacy of its is 95%.

Moderna’s figure is an estimate based on a

peek at data being gathered in a continuing

trial involving 30,000 volunteers. Pfizer’s

comes from the final analysis of a trial in-

volving 43,000 people, in which 170 cases

of covid-19 were seen. Of these, 162 were in

the placebo arm (ie, those involved had re-

ceived dummy injections).

The news bodes well for a third candi-

date, from AstraZeneca and Oxford Univer-

sity. This pair have, rather notably, not re-

leased any interim data from their trials so

far. They have also been vaguer about when

their vaccine might be available, saying

only, “the end of the year”. But it is thought

their trials are only weeks away from hav-

ing a full set of data. Mene Pangalos, Astra-

Zeneca’s head of r&d, told the Greenwich

Economic Forum, a conference held last

week, that the firm might apply for full ap-

proval—rather than the emergency autho-

risation sought by the other two pro-

jects—in America, and perhaps in Britain

and other parts of Europe as well.

More good news was to be found among

the details of how, and for whom, these

vaccines work. All the severe cases of covid

were seen in unvaccinated volunteers. It is

also now clear that the vaccines worked in

participants of a range of ages, including

those over 65, and from a variety of ethnic

backgrounds. This means both vaccines

Another new vaccine arrives, and a

new class of drugs is born

Covid-19 vaccines

And then there

were two