Capturing our First Planetary Snapshots

 

Kepler has confirmed more than 1000 planets outside our solar system, but so far only a few of Earth-like size and in the habitable zone — rocky planets with just the right temperature for liquid water. And none of those potential Earth-analogues have been observed directly, but through the interpretation of astronomical data, such as the wobble of the star, or the dimming on the star’s light due to planetary transit.

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So far, some pictures of other planets have been taken from ground-based telescopes, but those planets are large, bright and orbit far from their suns — not like potential Earth-twins which will be far smaller and orbit closer to their suns.

NASA scientists and engineers are working on two new technologies to help look for new planets, a starshade and a coronagraph, which will both work to block the light of the star, allowing the telescope to examine the reflected light of the planet itself.

This means we can not only take pictures of prospective Earth-like planets, but also use spectrographic analysis to analyse what in their atmospheres as well. This will give us clues to what might exist there. For example, evidence of plant life and animals similar to those on our Earth would show up as a series of simple signature compounds in the planet’s atmosphere: such as oxygen, ozone, water and methane.

A starshade is a type of spacecraft that actually flies in front of the telescope to block the light of the sun under observation. Despite the fact it will be only tens of metres wide, it will fly quite a bit in front of the telescope — in fact around 50,000 km away — more than four Earth diameters. Getting it into space is a challenge. It will be folded up like a super-origami prior to launch to unfurl in space,  somewhat like an unwinding spring, into to a crazy-sized sunflower. The pointed petals are crucial to its design: they control the light the right way to reduce the glare to levels where planets can be seen. The petal-fringed shape creates a softer edge that causes less bending of the light waves.

Both the starshade and the telescope will be independent spaceships, allowing them to move into just the right position for observations. The petals of the starshade need to be positioned with millimetre accuracy.

Blocking out the starlight while preserving the light emitted from the planet is called starlight suppression.

The light of a sun can be billions of times brighter than the reflected light from the planet. Our own sun is 10 billion times bright than Earth.

Coronagraphs were originally introduced in the early 20th century to study our own sun, blocking out the light from the sun’s disk to allow scientists to study its outer atmosphere, or corona; hence coronagraph. They are much smaller than the starshade, located within the telescope itself.

These starlight-blocking coronagraphs will be more sophisticated.

These new generation coronagraphs uses multiple masks as well as smart mirrors that can deform, to suppress starlight in sequential stages. There are many other challenges in delivering the coronagraph technology, including being able to suppress or compensate for the warping and vibrations that all space telescopes experience.

Need Dry Ice? Try Mars.

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A new study on the Red Planet suggests that the sharply etched channels that crisscross its surface may have been cut by frozen CO2, rather than water.

The contention is that these gullies are very much active, and continue to form on Mars even now in cold weather. If that’s the case, than it is almost certainly ‘dry ice’ or frozen CO2 that is developing this geological feature.

Recent photographs captured by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter, have enable a new look at the phenomenon, allowing researchers such as lead author Colin Dundas to examine the timing of gully formation over the last couple of years.

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The conclusion was that the gully formation is occurring in winter, when the Martian atmosphere is condensing out as a solid. Unlike Earth, where the temperature and pressure conditions for the formation of dry ice does not occur in nature, on Mars they occur every winter, most notably in the form of a seasonal polar ice cap.

As many as 38 sites have now been identified as showing active gully formation. All at times when it would be too cold for liquid water to flow.

So if your heading out the Red Planet – don’t forget the Beer Cooler. The dry ice is free :).

 

Yes – Our Solar System Really is Weird

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The lengthening lists of new planet finds have allowed astronomers to start building on the science and knowledge of planet and solar system formation to draw some fascinating conclusions.

According to Astrophysicist Lars Buchhave (Harvard-Smithsonian Centre for Astrophysics) there are three sorts of solar system. The key to the classification system is the elemental composition or ‘heaviness’ of the progenitor nebula – specifically how metallic they are. Rather than the observation of a smooth transition between these three types, the collected data on exoplanets shows distinct types of solar system with little in between.

Planets above a blue planet

Planets around the most metallic stars tend to be big – gas giants in the Jupiter class and above. The reason being that the presence of these heavier elements allows more planetary development before the protostar ignites, allowing the growing planet to get heavy enough to attract the lighter elements of hydrogen and helium.

Planets around the least metallic stars tend to be mainly rocky planets, but larger than the rocky planets around our own sun

Those suns in the middle range of metallicity are associated with a third (unfamiliar) type of planet called gas dwarfs. These planets have rocky cores, but are large enough to hold an atmosphere of hydrogen and helium.

So where does our own solar system fit in? Apparently nowhere. Our solar system with our four small rocky planets and four gas giants is an unusual one. In terms of the metallicity spectrum, Earth’s Sun is an example of a metal-rich star, common in the spiral arms of the Milky Way galaxy, so I guess at least our gas giants make sense based on this latest theory.

This got me thinking. Maybe our solar system was formed in the collision of two proto-systems early on? Would this explain the weird fact that Venus rotates in the opposite direction to all the other planets that spun off the ecliptic? Perhaps a metal-poor (Population II) star that went supernova leaving its drifting rocky planets to be snapped up by our Sun?

This oddness in our planetary composition is just the latest in a series of weirdness that relates to our solar system. I’ve noticed this before. The more we look – with the benefit of science – the more atypical we are. Like how both the Moon and the Sun are exactly the same angular size in the sky.

Some of these strange coincidences allowed the development of life as we know it. Jupiter has had a very positive role in protecting life on Earth, acting as our planetary ‘guardian’, preventing many of the asteroid impacts that would have sent life back to the drawing board again and again.