Scientists say they may have detected what might be complex carbon compounds on the surface of the comet the craft landed on two weeks ago.
The results are from the Ptolemy instrument which is a miniaturised on-board laboratory.
The detection of carbon supports a view that comets may have brought key chemicals to Earth to kick start life.
The team leader Prof Ian Wright has told BBC News: “We can say with absolute certainty that we saw a very large signal of what are basically organic (carbon) compounds.
“There is a rich signal there. It is not simple, it is not like there are two compounds, there is clearly a lot of things there – a lot of peaks. Sometimes a complicated compound can give a lot of peaks.”
The “peaks” refer to the graph produced by the Ptolemy instrument of the different molecules it has detected. The result in line with initial observations made by a similar German led instrument on Philae.
In an exclusive interview with BBC News Prof Wright explained that Ptolemy had gathered huge amounts of scientific data. Normally a quiet understated man, he was marginally better at containing his enthusiasm than his co-worker and wife Prof Monica Grady, who jumped for and then wept with joy and relief when Philae landed.
Prof Wright told me: “I am as excited now as I was a couple of weeks ago. It’s tremendous!”
Tense moments as the Ptolemy team wait to see how much of their data will stream back before Philae’s power runs out
“For years I’ve been giving public lectures about what we plan to do. Now we have some data and now it’s: Wow! This is what scientists do this stuff for.”a
Much of the data gathered by Ptolemy was collected on the fly. Shortly after the Rosetta spacecraft was activated in January, Prof Wright and his team saw the opportunity to analyse the comet’s tail as the spacecraft approached.
“It is not something we had planned to do but it became obvious that it was something we could do.”
The early data suggests that the composition of the gases changed as the spacecraft got closer to the comet.
Prof Wright also explained that Philae’s bouncy landing suited his experiment. Among Ptolemy’s capabilities is to analyse gases and particles around it and so it was pre-programmed to sniff its environment shortly after landing.