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We are finally going to get to see what Pluto looks like, thanks to the New Horizons mission, which is set for a closest approach on July 14. It’s amazing to me that as much as we know about the solar system (and indeed the Universe) that we have not ever really gotten a good look at this object. The problem is that Pluto really is that far away from Earth – New Horizons launched 9 years ago and is only getting there now. The images it is sending back are already so much better than anything we’ve yet seen – and they are so tantalizing.

Here are a few of the latest images from New Horizons – but stay tuned because more are coming in – and closest approach is less than a week away.

Pluto, July 8

This image of Pluto from New Horizons’ Long Range Reconnaissance Imager (LORRI) was received on July 8, and has been combined with lower-resolution color information from the Ralph instrument.

Pluto, July 1 and 3

The Long Range Reconnaissance Imager (LORRI) obtained these three images between July 1 and 3 of 2015. The left image shows, on the right side of the disk, a large bright area on the hemisphere of Pluto that will be seen in close-up by New Horizons on July 14. The three images together show the full extent of a continuous swath of dark terrain that wraps around much of Pluto’s equatorial region. The western end of the swath (right image) breaks up into a series of striking dark regularly-spaced spots, each hundreds of miles in size, which were first detected in New Horizons images taken in late June. Intriguing details are beginning to emerge in the bright material north of the dark region, in particular a series of bright and dark patches that are conspicuous just below the center of the disk in the right image. In all three black-and-white views, the apparent jagged bottom edge of Pluto is the result of image processing. The inset shows Pluto’s orientation, illustrating its north pole, equator, and central meridian running from pole to pole.Credit: NASA/JHUAPL/SWRI

I also wanted to talk a bit about something that I’ve been writing about recently for Blueshift – the idea that science is collaborative and cooperative. And I don’t even mean just between scientists or institutions, but the idea that to understand something, you need to see it from lots of different perspectives. This can mean studying an object at different wavelengths – but also means using the different tools at our disposal. Imaging is great, but to really understand an object, we also need to use things like spectroscopy – looking at and breaking down the light an object is either giving off or reflecting. It’s one way we can understand the chemical make-up of an object.

Some missions have multiple instruments and can do a range of observations on an object. Sometimes a mission has a particular strength in one area and scientists benefit by using data from other missions. Since it’s a mission I’m familiar with and work on, I will, of course, use the James Webb Space Telescope as an example. JWST is often thought of as a mission that will see only far away things – but it will actually make observations of objects in our solar system as well. (As long as those objects are not in the direction of the Sun! JWST can see from Mars on out. Any inner solar system bodies would make us point towards the sun and warm up the telescope!) JWST will have powerful spectrographs on it and can, for example, be used to observe Saturn. Cassini, which is there now, will end its mission in 2017 by crashing into Saturn, so JWST will help scientists to keep up with their seasonal observations of Titan (and other bodies in the outer solar system), and also be able to provide data at wavelengths complimentary to Cassini.

The question then is – can JWST observe Pluto? And what will it tell us? I chatted with planetary (and JWST) scientist Dr. Stefanie Milam about this – and I thought I’d share her answer to me.

New Horizons will get a glimpse of Pluto during its approach/flyby on July 14, and give us unprecedented details of the surface composition with images and some spectroscopy. Precursor images from ground-based facilities do not compare to that mission’s image quality – however, this will be a recording of only one moment of Pluto’s long journey around the sun. New Horizons will offer maps of the surface features down to about 250 meters from its camera as well as map the amounts of nitrogen, methane, carbon monoxide, and frozen water and other materials with spectrometers on board.

The James Webb Space Telescope will offer further insight and follow-up for the New Horizons findings. While imaging Pluto with JWST is not nearly as defined, offering only a few pixels across, the unprecedented spectral sensitivity and factor of ~6 in spectral resolution will allow for the detection of new species, determine isotope ratios, and routinely measure the water and methane temperatures on the planet. Regular observations of these volatiles and ices will provide details on seasonal variation in the composition. Pluto experiences solstice in 2029, and may express significant changes in abundance and perhaps composition as that time approaches.

JWST Pluto Observation Capabilities

The figure above shows some of the features that can potentially be observed using the Fixed Slit (FS) mode of NIRSpec. The shaded region marks the comparable near-IR coverage from New Horizons Ralph instrument. Credit: NASA

Planetary Missions

There are no outer solar system missions after Cassini until 2030! Image credit: Stefanie Milam

And this is why science is great. New Horizons is going to do a truly amazing thing – give us our first real look at Pluto – and it will be able to make measurements of the elements present there and do some mapping. But it is only a glimpse. We’re going to want to know so much more once we’ve had a taste of what Pluto can offer us. I’m sure New Horizons will (as many missions do) create so many more new questions than it answers. And the fact that missions like JWST (and the missions that will come after JWST) can team up with current missions to give us more pieces of the puzzle is what makes exploring our universe so exciting.

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