THIS WEEK

14 | NewScientist | 21 September 2013

FIND a clear, dark sky and look for a constellation shaped like a giraffe, and you may see the future resting place of Voyager 1.

After years of repeated but unconfirmed rumours that the spacecraft had broken free of the sun’s protection, NASA scientists announced last week that the probe entered interstellar space in August last year.

Voyager 1 has enough nuclear

fuel to keep doing science through to 2025, and then it will be dead, adrift. On its current trajectory, the probe should eventually end up within 1.5 light years of a star in Camelopardalis, a northern constellation that looks like a cross between a giraffe and a camel. No one knows if there are any planets around that star, nor if aliens will be in residence by the time the probe arrives.

“But if they are there, maybe they will capture Voyager 1,” says

mission scientist Tom Krimigis of Johns Hopkins University in Baltimore, Maryland.

Since 2004 Voyager 1 had been travelling through a border zone in the heliosphere, the magnetic bubble blown by charged particles streaming from the sun. The motions of objects beyond the heliosphere showed that the charged gas, or plasma, that fills the space between stars should be much denser outside the border than within, and the Voyager team was at last convinced of an exit from the heliosphere thanks to a sudden increase in plasma density.

Oscillations in the plasma surrounding the probe seen in late 2012 and early 2013 showed that

its density has been on the rise and is now about 40 times higher than it was before. Extrapolating backwards, the increase must have started on 25 August 2012.

This corresponds to readings from another of Voyager 1’s instruments, also taken in August last year, that showed a drop in solar cosmic rays hitting the probe. Instead, the craft saw an excess of galactic cosmic rays, which come from sources outside the heliosphere. Together, the lines of evidence suggest that Voyager 1 has truly crossed over.

The probe may no longer be bathed in solar particles, but the galactic cosmic rays show that its surroundings are still being tugged on by solar magnetic field lines. This suggests Voyager 1 is in a final transition zone.

Premature reports of the probe’s “exits” from the heliosphere show how little we know about the solar outskirts. So what will Voyager 1 tell us about them? “I’m very reticent to make predictions when our track record is so poor,” says Krimigis. “But I do anticipate surprises.”

As the craft ploughs deeper into the galaxy, the NASA team will look for an anticipated change in magnetic field direction that would indicate that Voyager 1 is at last clear of all solar influences except gravity, as well as anything that can be gleaned about interstellar space, before we lose contact. n

Michael Slezak and Lisa Grossman

–Drift long and prosper–

Voyager 1 hits space betwixt the stars

Healthy living turns back the ageing clockHERE’S yet another reason to follow a healthy lifestyle: it can reverse ageing – in cells, at least.

The finding relates to telomeres, the caps that protect the tips of chromosomes when cells divide. With each cell division these get shorter, so as we age they wear away like a candle wick burning down. Now it seems that telomeres can regrow if a

person’s lifestyle becomes healthier.The study involved 10 men in their

early 60s with prostate cancer, who were asked to follow a strict healthy-living regime rather than take a course of drugs. They ate a meat-free diet, did exercise and yoga daily, and went to weekly group therapy.

After five years, the telomeres on a type of white blood cell were 10 per cent longer on average in these men. In contrast, 25 men with the same condition who kept to their usual lifestyles saw the telomeres on these cells shrink by an average of 3 per cent over the same period.

“In a biological sense, they are getting younger,” says team leader Dean Ornish of the Preventive Medicine Research Institute in Sausalito, California, who says he is not yet sure of the mechanism causing the telomeres to regrow.

Studies comparing telomere lengths in individuals against the population as a whole suggest that shorter telomeres are linked with ill

health and a shorter life. Telomeres are known to regenerate in stem cells and some cancer cells, but this is the first time a lifestyle change has been shown to make them do so in ordinary cells (The Lancet, doi.org/nt4).

“The results hold promise for preventive medicine,” says Maria Blasco of the Spanish National Cancer Research Centre in Madrid. However, Carol Greider of Johns Hopkins University School of Medicine in Baltimore cautions that it’s unclear if the changes seen are real, or normal fluctuation in noisy data. Andy Coghlan n

“In a biological sense, the men following the healthy-living regime are getting younger”

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