Sunday, 17 April 2011

Success on Saturn

Tonight the observing gods are on our side - clear skies, low to zero humidity, and no problems with the telescope or its instruments. So Tom Stallard and I managed to get ~2 hours observing Saturn, whilst the Cassini spacecraft took a series of infrared images. Our infrared spectra of H-three-plus are designed to complement Cassini's Visual and Infrared Mapping Spectrometer (VIMS).

Our spectra on the Keck II telescope have nearly 100 times the ability to find the emission lines of individual molecules. But VIMS gets a much broader sweep of the whole spectrum of Saturn. Our spectra scan the planet from north-to-south, but only at one longitude - the noonday meridian, where the local time on Saturn is 12 noon. Cassini VIMS, however, gets a full picture of the northern hemisphere facing the spacecraft.

Tonight our Keck observations are also being backed up by Henrik Melin and James Donaghue working on the NASA Infrared Telescope Facility. They are getting images of the northern and southern aurora, at a wavelength sensitive to the H-three-plus emissions.

That means that, between the ground-based observations and the spacecraft, we should build up a really good picture of what's happening to Saturn's atmosphere on a semi-global scale. And that's important, because it enables us to understand all the pressures pushing and pulling the ringed planet.

Europe's planetary scientists have not been so good at carrying out this ground-based support for their space missions as their American colleagues. That's one of the reasons for Europlanet's NA1 "Ground-based support for space missions" activity.

Friday, 15 April 2011

Yet more frustration

Following on from Henrik Melin's and Tom Stallard's blogs, it's a shame to have to report that the weather on Maunakea is still playing with us unfairly. Tom and I are currently using the Keck II telescope. This is one of the William Keck Observatory's two 10-meter telescopes on the summit. Our target is Saturn; our purpose to support observations being made by the Cassini spacecraft orbiting the Ringed Planet.

Except ... just when the sky is clear, the air immediately around the telescope has decided to get rather too moist for observing. The danger is that drops of water, or even ice crystals, will start to form either on the primary, light-gathering, mirror, or on the secondary mirrors, that focusses the light back down into the instruments. So, after a few short observations to show that we really could get the spectra of Saturn that we wanted, the weather has decided that we can't! And it looks as if by the time we can open the telescope again, Saturn will have dropped below our horizon.

It's at times like this when you realise that astronomy really is real-time. Saturn will never be quite the same again, and if it had been doing something really, really interesting, well - we missed it. Never mind, we have another shot at it in two days time - weather permitting.

So our plan had been to try to measure the spectrum coming from Saturn's upper atmosphere at a very high spectral and spatial resolution. The upper atmospheres of giant planets are composed mainly of molecular and atomic hydrogen, into which a bit of helium has been mixed. Sunlight and the impact of high-energy electrons, hurled at the planet from its magnetosphere and the solar wind, create a third form of hydrogen called H3+ (H-three-plus) that consists of three hydrogen atoms joined together and then ionised by the loss of a negative electron to form a positively charged, molecular ion.

H3+ is a signature molecule; it shows up where energy is being deposited into Saturn and energetic processes are occurring. Tracing where it is to be found, how much, and how hot, helps us to understand just how the saturnian magnetosphere - that region of space controlled by Saturn's magnetic field - couples into the planet itself. And we are hoping that will then help us to understand some other key questions - like why is the upper atmosphere of Saturn (and Jupiter, Uranus and Neptune) much hotter than it should be, based on the amount of sunlight the planet receives.

Tonight, Tom and I are not actually on the summit of Mauna Kea (4,200 meters above sea level) but at the much more comfortable 800-ish meter altitude level of Waimea. For the Keck observatory, working astronomers are kept pretty well oxygenated at the main HQ itself, communicating by video conference with the telescope operator, who is at the summit controlling things. It works pretty well, although I still prefer the hands-on feel of being at the summit and sitting next to the telescope operator.

PS we just got open again and onto Saturn - for one minute. Hey-ho!

Begin again

Sometimes the weather just doesn't treat you right, especially at 4km up a mountain. It is essential that, as an observer, you don't let it effect you. Getting mad at the weather isn't going to help, so you just accept your fate and wait it out. We finally came down the mountain, knowing that we had, at least, gotten three half nights of decent data. We brushed ourselves off, and slowly the weather cleared.

Now, it is round two. We have a second set of observations, this time, perhaps, even more important. Not only is Cassini observing Saturn's aurora, not only is Hubble, but now we have observations on both IRTF and Keck. Two of the best infrared telescopes in the world, both observing at the same time. Needless to say, it feels as if the weight of the long, slow run without result has lifted. Our IRTF observations begin tomorrow, but tonight is all about Keck.

The twin telescopes of Keck. In our observations, we will be using NIRSPEC on Keck 2, the dome on the right in this picture.

Keck consists of two separate telescopes, each of which have a ten meter dish, still considered close to the largest telescopes on Earth. Tonight, for a span of only two or three hours, we will focus in on the aurora of Saturn, hopefully producing the richest auroral infrared spectra ever seen from the planet. You can even look in on us between 11am-5pm on Friday 15th (BST).

Thursday, 7 April 2011

Thunder and lightening, very very boring

The thing we fear most arrived with a certain inevitability. A massive storm front crashed into the Hawaiian island from the North. I awoke yesterday to rain and hail so loud, I thought I'd left my heating fan on overnight. Today, as a change, I awoke to thunder. Astronomers fear high cirrus clouds because they block the view of the night sky, and they fear summit cloud, because the rain and snow can cause black ice, a real danger. We have both in great supply. And so the mountain turns from being a hard working environment, to an incredibly dull, unsatisfying one.

The all-sky camera at UH2.2 - during the day this typically shows clear skies and telescopes on the horizon, at night the milky way in all its glory. This is the picture today, rain on the lens and fog obscuring the telescopes

Instead of preparing for observations, observing at the summit and reducing the data the next day, we are caught at 3000m trying to do other work, work that doesn't interest us, all at the high altitudes that make concentrating so difficult. It is a lonely time at 3am, the entire building dark, when you're the only one awake. And now it is almost as quiet, 3pm, up before everyone because sleeping at the mountain is always a gamble. I usually sleep better than most, but in these conditions, the daily rhythm broken, I sit in a quiet office, trying to plow through admin work from back home as the mountain storm gently rumbles to me in the background.

Mauna Kea is regarded as one of the premier observing sites in the world, due to its dry clear air.

Monday, 4 April 2011

A storm's a brewin'

It is our third night here at the summit of Mauna Kea and already the nights are starting to drag by. No matter how important the observations you are making, or how amazing the night time sky or day time views, the slow drag of nightly repetition makes it hard to maintain concentration. This evening, though, our alertness has been raised by the weather. Not, you understand the weather at the summit, and certainly not the rain clouds that always lap against the eastern shores of the Big Island; these weather systems are far below us, looking more like an ocean of cloud from the summit. We are more concerned with the high clouds above us - cirrus.

An image taken from the GOES satellite - taken from the Mauna Kea Weather Center - showing the location of cirrus around the Hawaiian islands.

Cirrus clouds are the bane of an observer's existence, because these high ice clouds can cover over the sky, even when you observe from the top of a mountain as high as Mauna Kea. There's nothing you can do about them, but try and wait them out. Tonight, as you can see in the satellite image, we are riding the edge of a giant mass of cirrus to the south of us. Right now the sky is clear, but we saw our data getting scattered by thin wisps an hour ago. It could easily come back soon. To make matters worse, the even thicker set of cirrus to the north is slowly, day by day, forcing its way towards us and there are rumours of a storm coming. Storms are bad, because they cause hot air to rise much higher than is normal, dragging the water laden clouds with them. If they reach us, then the telescope has to close, in case water starts to condense on the telescope mirror.

So we sit, gripped by satellite imagery, high intensity all-sky cameras and even looking out at the night sky with night-vision goggles, hoping to understand what the weather holds for us.

Sunday, 3 April 2011

Observing Saturn at the NASA IRTF

Tom Stallard and I, both from the University of Leicester, arrived here at Mauna Kea in Hawaii a couple of days ago and have already spent a full night observing the aurora of Saturn. On our first night we observed for a whole 12 hours which is great since we can observe a complete rotation of Saturn (10 hours), but it can also be somewhat intense, especially with the effects that 14,000 feet of altitude has on mental aptitude. Luckily, we did get some great observations of Saturn and Tom tested out the live streaming of our observations to the web - more on that later.

We are using an instrument on the NASA IRTF called CSHELL, a high resolution spectrograph that allows us to look emission from a molecular ion called H3+, emitting in the auroral region on the planet. These observations will enable us both to determine how the wind is blowing at these high latitudes and what the shape of the aurora is, which in turn will tell us more about the processes responsible for the emission.

All in all, we are going to observe here at the IRTF for 14 nights, scattered throughout the month of April. At the same time we are observing Saturn here from the IRTF, the Cassini spacecraft, which is in orbit about Saturn, will also observe the aurora, both in the infrared (as we are) and the ultraviolet. During this period the Hubble Space Telescope (HST) will also turn its eye towards the aurora Saturn, and as if all this wasn't enough, Tom will head down to Waimea to operate the Keck II telescope for a copule of nights - the world's largest infrared telescope. All in all, this mounts up to a very exciting and unprecedented series of observations - helping us to better understand how the aurora of Saturn is formed and how it evolves over time.

If you would like to look in on us while we observe, then head to: - we are observing for the next week between midnight and 6am, Hawaii time. That's 11am and 5pm BST, or noon and 6pm CET.

Tom monitoring the incoming observations of Saturn's aurora. Note the image of Saturn as seen through the guide camera on the right.

Bill keeping an eye on the 1s and the 2s. Each monitor contains information about the status, health and movement of the 3.0 meter telescope.

The 3m NASA IRTF telescope and the shiny inside of the dome. The prime mirror cannot be seen from this angle, but is located in the base of the orange structure - at the top of which is the secondary mirror that reflects the light back down through a hole in the primary mirror to the CSHELL instrument. The height of the orange telescope truss is about 6 metres.

Saturday, 2 April 2011

Observing Saturn

Tom Stallard and Henrik Melin, planetary scientists from Leicester University in the UK, have arrived at  Mauna Kea, Hawaii, for an observing run of Saturn.  They are going to be using the Keck and NASA Infra Red Telescope Facilities to support observations from the Cassini spacecraft's VIMS instrument (to find out all about VIMS, see: .  On 12th April, they will be joined by Europlanet's Steve Miller.  Tom, Henrik and Steve will be blogging about their time up the mountain, here on the Europlanet Blog.  We are also going to be setting up some live chats, so you can ask them questions and get live feeds of some of the things that they will be looking at.