Asteroid Vesta comes into focus

13 June 2011 Last updated at 17:27 GMT By Jonathan Amos Science correspondent, BBC News Getting closer: Vesta is missing a big chunk out of its south polar region The Dawn spacecraft is starting to get an eye-full of the Vesta asteroid.

The probe expects to reach the 530km-wide body in late July, whereupon it will go into orbit around the rock.

Vesta is what scientists term a protoplanet - a body that never acquired the proportions of "grown-up" planets such as Earth and Mars.

It is nonetheless an impressive object - the second most massive asteroid in the belt of rocky debris that orbits between Mars and Jupiter.

Nasa's (US space agency) Dawn satellite will be spending about 12 months at Vesta before moving on to Ceres which, at 950km in diameter, is by far the largest and most massive body in the asteroid belt.

The new images released on Monday are a big improvement on the dot-like navigation shots released last month that were used to fine-tune the probe's approach to the rock.

The latest pictures were acquired on 1 June, from a distance of about 480,000km. Vesta's irregular form is now unmistakeable. In the images, one pixel corresponds to 45km on Vesta's surface.

In the days since 1 June, Vesta has started to acquire pictures with resolutions of around 30km per pixel - slightly better than the best shots we have from the Hubble Space Telescope.

"This is really a new world which we've never seen before, so it should be very exciting," said Dr Andreas Nathues from the Max Planck Institute for Solar System Research (MPS) in Germany which processed the imagery.

"We will have five times Hubble resolution by the beginning of July," he told BBC News.

The asteroid has the look of a punctured football, the result of a colossal collision sometime in its past that ripped a big chunk out of its south polar region (the five o'clock position).

The debris from that smash-up was sent far and wide. About one in every 20 meteorites that falls on the surface of the Earth is probably a bit of Vesta.

Ceres and Vesta will make for interesting subjects. They are both evolved bodies - objects that have heated up and started to separate into distinct layers.

In the case of Vesta, telescopes have spied evidence for the eruption of lava (basalt) on its surface.

"The goal is to acquire the first colour pictures of Vesta in early July," said Dr Nathues. "We will go into three different kinds of orbits and the last of these will be about 200km in height from the surface. The best resolution at that stage will be about 20m per pixel."

Jonathan.Amos-INTERNET@bbc.co.uk

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Energy saving plan comes closer

2 June 2011 Last updated at 10:36 GMT The cost of the work will be added to electricity or gas bills The government has revealed more details of its Green Deal scheme to help people pay for home insulation and other energy saving measures.

The plan should be launched in the autumn of next year.

Under it, authorised companies will pay for the insulation work and homeowners will repay the money, plus interest, through additional charges on their energy bills.

The government hopes people will repay loans of up to ?10,000, over 25 years.

Climate change minister Greg Barker said: "The Green Deal is the government's flagship energy saving plan to transform the country's homes to make them warmer and cheaper to run.

"From next year, people will be able to access up to ?10,000 upfront to pay for energy efficiency work, repaying the costs through savings on energy bills."

Legal changes

The scheme still requires a lot of work before it is ready to start.

A few firms such as Marks & Spencer, B&Q, Tesco and British Gas have expressed an interest in marketing the scheme and providing the finance.

But the law will need to be changed so that energy firms will be obliged to collect the repayments from homeowners via their energy bills.

The law will also need to be altered so that anyone who buys after the work has been done, but before the bill has been fully paid, is obliged to take on the debt and repay it.

These legal changes are included in the current Energy Bill, which is going through parliament and should receive its Royal Assent this July.

It has also not yet been decided just how much interest will be added to the loans.

How will it work?

The firms who eventually market the Green Deal will employ assessors to estimate just how much a householder can save through various insulation or heating measures.

These may include loft insulation, condensing boilers, draught proofing, solar panels and double glazing.

Once the work is assessed and agreed, the installation work will be contracted out to accredited installers.

Then the homeowners will have to start paying.

A key feature is that homeowners must be able to save more on their energy bills than they pay back.

What is the attraction for the big firms that the government hopes will market the scheme?

"Companies will see it as a marketing opportunity to sell other things," said a spokeswoman for the Department of Energy and Climate Change.

Anne Robinson, of the price comparison website Uswitch, said: "People who have the Green Deal will be paying a lot less for their energy after a year or two."

But Richard Lloyd, of the consumers' association Which?, warned against the dangers of shoddy workmanship.

"Our latest research into cavity wall insulation uncovered inadequate inspections and poor advice," he said.

"For this scheme to be a success, Green Deal assessors need to be held to the highest standards."

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