This image of the Orion Nebula was produced by a team of
astronomers and other specialists led by Dr Massimo Robberto of the
Space Telescope Science Institute in Baltimore, Maryland. This
truly vast reach of roiling dust and gas is approximately 1500
light-years away but is the nearest star-forming region to
Earth.
Q&A: DR MASSIMO ROBBERTOWhat goes
into capturing an image like this?
The Hubble Space Telescope image of the Orion Nebula is a
by-product of a scientific study that required imaging the full
region. About 10 years ago, it became clear that measuring with
high precision the main parameters (luminosity, mass, age etc) of
the ~3000 protostars forming in the Orion Nebula would provide
a critical contribution to our understanding of how stars and
planets forms. This required detailed observations with Hubble and
it is from these observations that we have reconstructed the
image.
In more detail, the process starts with the write-up and
submission of a science proposal for obtaining observing time with
the Hubble. This is a highly competitive process, as only a small
fraction of the proposals can be approved and get time. I have put
together an international team of about 15 renowned experts that
helped me write the science justification. Plus, I had to craft a
clever way of using the satellite to reduce our request to
"only" 104 orbits of telescope time, still a large amount. One
orbit takes about 96 minutes, but only about 45 minutes can be
used to take data (the rest of the time the Earth is in the
way).
The proposal was ranked very high and we got our Hubble time. The
next step was the preparation of the observations, i.e.
the choreography that has to be executed by the telescope
to perform the program. This is basically a long list of
commands, detailed to one second of accuracy. The Space Telescope
Science Institute provides software and specialists to support
astronomers in this phase. Then the data started arriving, spread
over a period of six months, as we designed. I had a small team of
three analysts helping me with the analysis of each image, to make
sure there were no problems. Then we started the process of
removing all instrumental artefacts (again, the Space Telescope
Science Institute provided the needed software and support) and
combined the images into sub-mosaics. This process lasted about one
year. At the end, we were ready to begin our analysis, i.e.
measuring the properties of the stars. At the same time, I
delivered the sub-mosaics (35 pieces) to Zolt Levay and his
graphics team at the Space Telescope Science Institute. Zolt put
together the full mosaic, consulting me for the optimal choice of
colours in order to reproduce the most realistic view of the
region. I provided him with some ancillary data I had taken in
Chile to fill gaps at the edges, and he finally delivered the
image.
Overall, about 50 people were directly involved with the
production of the image.
Does the image represent only visible light, or is it a
synthesis of visible light and other wavelengths?
Unlike commercial CCD cameras, the Hubble instruments use
CCDs that take pictures in black and white. The instruments,
however, have a large selection of filters (basically, coloured
glass) that we can use to select particular wavelength ranges. So,
for a three-colour (RGB) image we need three different images. In
the case of the Orion picture, we had taken five images, so Zolt
Levay could play with two extra colours to synthesize the
final image. Of our filters, four selected wavelengths visible to
the eye, while a fifth one selected a wavelength that we cannot
see, in what I would call the "very-near Infrared" spectral
region (about 8,500 - 10,000 Angstrom).
How do you categorise your work? Is there an aesthetic
aspect and an interest in the mystery of the cosmos or is it a
matter of scientific discovery and mathematical
clarity?
I would say both, and I would say that there is no difference.
'Cosmos' in Greek means 'order' (the opposite is 'Caos'), not
'space' or 'sky', for which the right word is 'Uranos'. Cosmos is
the right word to describe reality, which has a profound order that
we can discover and understand with our reason. I find it amazing
that our reason can understand the cosmos, as we are so limited and
'animal' in so many respects. There is a unique reason, a common
'logos', to use another Greek word, that we find in us and in what
we have in front of us, at any single instant. I find that true
beauty lies here, finding this more profound order in reality and
realising that it corresponds, mysteriously, to what we are
made of, and for.
This image was produced back in 2006, what are you working
on currently?
I am quite busy working on the next giant space
telescope, the James Webb Space Telescope, that we plan to launch
in 2018. It will be an infrared telescope of unprecedented
capabilities and will revolutionise astronomy. But I am also still
working on the Orion Nebula. Our science program is a real treasure
chest that we are still mining for discoveries, plus it allowed us
to carry out extremely interesting follow-up observations. I should
remark that a generation of post-doctoral students that worked with
me on Orion is now growing into first-rank astronomers, bringing
new leads and ideas. This may well be the most important
contribution of the project.
Vere
(Faith), 6 Nov - 7 Dec 2013, Drama Theatre, Sydney Opera
House