13 March 2010 | NewScientist | 7

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A SERIES of 12 fly-bys by Europe’s Mars Express spacecraft are about to uncover the deep secrets of Mars’s moon Phobos. The passes will map its gravitational field

more thoroughly than ever before, and should reveal the distribution of material within. Six of the planned fly-bys have so far been completed, including the closest ever pass to Phobos, at 67 kilometres, last week.

The craft is equipped with a radar system, MARSIS , which will probe for underground structures in the moon, thought to be riddled with caverns. The gravity data will help Russia’s Phobos-Grunt mission, due for launch in 2011 or 2012, manoeuvre accurately around the moon before landing.

New portraits of Phobos are also on the way. “Until now, the encounters have been on the [moon’s] night side,” says Olivier Witasse of the European Space Agency. “This week we switch to flying by the daylight side, allowing the camera and spectrometers to begin working.” That will hint at the moon’s composition, testing the idea that Phobos formed from rocks that had been orbiting Mars .

Closer encounters

AND the award for being the world’s largest emitter goes to: the US. Europeans import nearly twice as much carbon dioxide per head, but the US is still dirtier.

The Carnegie Institution for Science in Stanford, California, reports that in 2004 23 per cent of global CO

2 emissions went in

making products that were traded internationally, many from China.

The average European is responsible for adding more than

4 tonnes of CO2 to the atmosphere

from the manufacture of goods imported from other countries. For people in the US, the figure was nearly half that – 2.5 tonnes – thanks to US exports of emissions-intensive goods that offset much of the CO

2 it imports

(Proceedings of the National

Academy of Sciences, DOI: 10.1073/pnas.0906974107).

The Carnegie study is one of a growing number that track emissions based on where goods are consumed. Official national inventories currently only consider emissions produced in each country’s own territory.

“We have to understand that

others are emitting on our behalf to make our goods and services,” says co-author Ken Caldeira.

Another study, which Glen Peters of Norway’s Center for International Climate and Environmental Research in Oslo is to publish soon, shows the US still leads the world in CO

2 emissions

even though its exports offset some of its territorial emissions.

Ice up and downThe US National Snow and Ice Center

reports that the average extent of

sea ice in the Arctic for February

was the fourth lowest since satellite

records began in 1979 . Meanwhile,

Antarctic sea ice is up slightly: its

summer minimum is 88,500 square

kilometres above the average for

1979 to 2000.

Shakers and moversThe magnitude 8.8 Chile earthquake

moved a city. Using GPS

measurements, Mike Bevis of Ohio

State University, Columbus, and

colleagues found that Concepción,

the closest city to the epicentre of

the recent quake, moved around

3 metres to the west.

He’s electricThe physicist Arthur Rosenfeld,

who helped California reduce its

electricity use , will have a

measurement unit named after

him. The “Rosenfeld” will be the

unit for emissions reduction and

energy saving, with 1 Rosenfeld

representing the amount of

electricity used by a US city with

a population of 250,000.

Ultra-fast star tangoA pair of white dwarf stars have

been seen revolving around each

other in 5.4 minutes. Hawaii’s Keck

telescope observed the binary

system, called HM Cancri, whose

diameter is no more than 8 times

Earth’s (The Astrophysical Journal

Letters, vol 711, p L138).

Blood simple?The collection of umbilical cord

blood by untrained hospital staff and

parents could be harmful to mothers

and babies, and render samples

useless, says the UK’s Human Tissue

Authority. The warning follows

reports of staff being pressured to

collect cord blood – and even parents

doing it themselves in car parks.

Whether cord blood, which contains

stem cells , is an insurance policy

against disease remains unclear.

Far-flung footprint

Herpes vaccine

“The gravity data will help Russia’s Phobos-Grunt spacecraft to manoeuvre accurately before landing”

“We have to understand that others are emitting on our behalf to make our goods and services”

THE love of your life has genital herpes: do you sleep with them anyway? It’s a dilemma that could vanish if a new approach to a herpes vaccine is successful.

The vaccine fights the herpes simplex 2 virus (HSV2), which coexists with the humans it infects for long periods, only rarely causing bouts of sores. It achieves this feat by suppressing its host’s immune system, and this has meant attempts to use the virus itself as a vaccine have failed.

Now researchers at BioVex in Woburn, Massachusetts, have produced a vaccine by deleting five of the virus’s genes. The altered virus neither causes disease nor suppresses our immune system. Animals that had been injected with the altered virus did not develop symptoms when exposed to normal HSV2.

BioVex will now begin trials of the vaccine in people in London.

60 SECONDS

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Europeans import twice as much CO2 per capita as US citizens,

but the US remains the biggest net emitter

Major CO2 importers Major exporters Flow of CO2 emissions in trade

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