MIRI: Preparing for Send-Off

MIRI in all its glory, in RAL Space's clean rooms at STFC's Rutherford Appleton Laboratory, 8th November 2010.

This past week I spent a few days in Leiden for a meeting of MIRI’s European Consortium, of which I’m a memebr, and a number of our closest US collaborators from NASA, the Space Telescope Science Institute and the University of Arizona. Over the summer, we completed our final test campaign for the instrument at the Rutherford Appleton Lab in Didcot.

For 86 days a fully assembled MIRI was held at its chilly operating temperature, 7 Kelvin, inside the cryo-chamber at RAL. During this time, every single wheel and pixel of the instrument got a workout, and with our test equipment, specifically designed to emulate scientific operations on board the James Webb Space Telescope (JWST), we got to see the first science-like images from all parts of the instrument, the imager, coronagraph and the spectrographs. Apparently this is the longest a space instrument has ever been tested continuously at cryo temperatures in Europe, prior to delivery.

Some other fun stats: 51 people worked for around 6000 person-hours (I did a measly 80 of those); we produced 6.5 terabytes of data, consisting of 8562 exposures, 2,775,036 detector frames. Those 51 people now have on average 168 exposures to work through – and that’s a conservative estimate, as not all 51 people are involved in the in-depth test analysis.

The completion of the test campaign in early August got some good coverage in the media, which was great to see.

Our meeting this week was the first opportunity for the team to get together in person and discuss our results since testing ended, and it was amazing to see how much work everyone’s turned around in such a short space of time. The good news is that all is essentially well with MIRI, and we’re making good progress towards confirming the requirements for its performance that we set out to verify. We have a few more crazy busy weeks to complete our analyses and the accompanying small forest of documentation, and that will be a huge milestone on our way to delivering MIRI to our NASA colleagues around the end of the year.

Working on an instrument in its earliest phases of operation, as MIRI’s test team is currently doing, can seem pretty dull to many astronomers. We’re not working with images of exoplanets, or of high-redshift galaxies, and test data are not the stuff of Nature papers – career-wise, that can be problematic at times. No one wins prizes for studying noisy pixels in the lab.

But the only way instruments can be successful is when the scientists have all the information about the data at hand to interpret their observations scientifically – and that is a big aspect of what the test campaign is all about. As well as checking that MIRI works properly, our in-depth study of this huge dataset will help provide the blueprints of the data analysis recipes scientists will use when analysing their MIRI observations. And win Nobel prizes, etcetera.

In case you’re wondering, I’m of course well aware of the huge pink elephant in the room: will JWST ever fly, and if not, isn’t this all a huge waste of time? The main news on the top-level troubles for the telescopeĀ  is that NASA has formally announced it’s working towards a 2018 launch date, at a projected cost of $8.7 bn [pdf].

I continue to support JWST as a hugely important, inspirational and audacious scientific undertaking, and I think I would still feel that way even if I weren’t so closely involved. But considering the basic facts that are on the table, the cost overruns and launch delays, there’s clearly a discussion to be had. Some good recent analysis and comment here, here, here.

From where we stand here in Europe, it’s important to dig in and work hard – good news from MIRI is good news for the mission.

In the next few months the team will navigate the road to gaining official acceptance for MIRI by the JWST project leadership at NASA. Behind that simple word, “acceptance”, lies all manner of bureaucracy that no one particularly enjoys being familiar with. But it will be a momentous milestone that we are sure to celebrate. All that stands between us and the party of the decade in Didcot is 6.5 TB of data and several thousand pages of documentation. I’ll keep you posted.

[Update, 12/09/11 – The SaveJWST page on facebook posted the following announcement earlier: “SaveJWST has received word that, on Thursday, September 15th the Senate Appropriations Committee [http://1.usa.gov/HPFZm] will be marking up [http://1.usa.gov/omrFw2] the House Subcommittee bill that proposed cancellation of JWST this past July. ” So it looks like the Senate battle begins this week.]

[Update, 12/09/11 – another MIRI test teamer and PhD student in my former group in Leiden, Rafael Martinez,has written about JWST here, in Spanish.]

[Update 13/09/11 – and here’s a nice and clear post from Phil Plait.]


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