- Messenger is expected to hit the surface of Mercury on April 30
- Probe has been orbiting Mercury since 2011, taking 250,000 pictures
- Latest image shows features such as volcanic vents and fresh craters
After four years orbiting the closest planet to our sun, the Messenger spacecraft will this week make a death-dive into Mercury.
But
the probe hasn't finished its mission yet, with new, detailed views
emerging of the planet as Messenger spirals closer to its surface.
Now
Nasa has released an image taken by the probe's Visual and Infrared
Spectrometer (Virs) revealing distinct features such as volcanic vents
and fresh craters.
Nasa has released an image taken by
the probe's Visual and Infrared Spectrometer (Virs) to reveal distinct
features such as volcanic vents and fresh craters. To highlight the
geological features, the images have been overlain on a black and white
mosaic from the Mercury Dual Imaging System (MDIS)
To
highlight the geological features, the images have been overlain on a
black and white mosaic from the Mercury Dual Imaging System (MDIS).
This is an instrument with wide- and narrow-angle cameras that has been mapping the rugged landforms on Mercury’s surface.
The
spacecraft is expected to smash into the planet's surface at 2.4 miles
per second (3.9km/s). The event will take place on Thursday 30 April at
3:30pm Eastern Time (7.30pm GMT).
However, when it does, Messenger will be behind Mercury, and hidden from Earth.
'The last couple of hours will probably be pretty quiet,' Mercury mission head Sean Solomon told Nature.
'There will be a final orbit when the spacecraft passes behind the planet and we won't hear from it again.
'I
have worked on the mission for 19 years. It's like losing a member of
the family. Even pre-knowledge doesn't prepare you completely for the
loss.'
The Mercury Dual Imaging System (MDIS)
is an instrument with wide- and narrow-angle cameras that has been
mapping the rugged landforms on Mercury’s surface. It was used to helped
create these images of Mercury
The spacecraft is expected to smash into the planet's surface on Thursday 30 April after a four-year mission
Among
the features Messenger has revealed to scientists in the past month are
patterns of distinctive hollows - each around a couple of hundred
metres wide - in the bottom of a huge impact basin.
It has also sent back detailed images of huge 1.2 mile (2km) high cliffs that cut across a crater named Duccio on the surface.
Another image shows a 621 miles (1,000km) long cliff that rises 1.8 miles (3km) above the surface, called Enterprise Rupes.
Data
sent back by Mercury suggests these cliffs, or lobate scarps as they
are called, have formed as Mercury has cooled and contracted over time,
creating dramatic tectonic faults on the surface.
Another
image shows a meteorite crater that has almost completely filled with
lava on Mercury's northern volcanic plains, leaving just the hint of a
rim behind.
It
also shows how the contracting surface of the planet has also created
strange formations where ridges and cliffs have hit other lava filled
craters.
Among the images sent back by
Messenger as its mission draws to an end is this picture of 1.2
mile-high (2km) cliffs cutting through the Carnegie crater. They are
thought to have formed as Mercury cooled
Distinctive hollows on the floor of the Zeami impact basin on Mercury can be seen in this Messenger image
Andy
Calloway, Messenger Mission operatoins manager at Johns Hopkins Applied
Physics Laboratory, said: 'The Messenger spacecraft operates in one of
the most challenging and demanding space environments in our solar
system.
'We
have met that challenge directly through innovation and hard work, as
exemplified by the stunning discoveries and data return achievements.
'Our
only regret is that we have insufficient propellant to operate another
10 years, but we look forward to the incredible science returns planned
for the final eight months of the mission.'
Launched
in August 2004, Messenger has traveled more than 4.9 billion miles (7.9
billion kilometers) during its mission to Mercury.
Its
journey included 15 trips around the sun before it entered orbit around
Mercury in 2011 - the first spacecraft to ever do so.
During
its mission is has acquired more than 250,000 images and collected more
than 10 terabytes of data with its suite of seven instruments.
It
has helped reveal volcanic vents that measure up to 15 miles (24km)
across that were once sources for the large volumes of lava that have
covered the surface and carved out valleys.
It
has also revealed Mercury's complex internal structure and that the
planet has an unusually large core that is still partially liquid.
On 6 April engineers used the last of the Messenger spacecraft's hydrazine fuel to try to push it into a higher orbit.
However, the tanks ran dry before they could raise it to more than 11 miles (18km) above the surface.
This image shows some of the mysterious irregularly shaped hollows on Mercury's surface in greater detail
The above artist's impression shows
Messenger as it orbits above the surface of Mercury. It is due to impact
on the surface at the end of April as the planet's gravity slowly pulls
it down out of its current orbit
Messenger has also revealed the
temperature of Mercury's surface. This image of the planet's north pole
shows the extreme heat it is subjected to with red indicating
temperatures greater than 126°c and blue -220°c