Rosetta team prepare as lander’s comet thunders on towards sun
SCIENTISTS are gearing up for a rollercoaster ride as the Rosett a mission comet reaches its closest point to the sun.
The event, known as perihelion, occurs tomorrow, and could be dramatic – perhaps even resulting in Comet 67P/ Churyumov-Gerasimenko breaking in half.
As a comet’s orbit takes it nearer to the sun its activity increases, causing ice to vaporise and gas jets to burst out from its interior.
This is happening now around Philae, the Rosetta lander that bounced onto the surface of Comet 67P last November.
On Thursday, the comet’s 6.5-year orbit will swing it to a distance of 186 million kilometres (115.5 million miles) from the sun, causing temperatures on its frigid surface to peak.
Over the past few weeks the Rosetta spacecraft has been witnessing the comet’s growing activity from its orbital vantage point.
On Wednesday, July 29, instruments on the orbiter recorded a dramatic outburst from the comet nucleus.
The eruption was strong enough to push away the incoming solar wind, the stream of magnetically bound energetic particles from the sun.
Images taken by Rosetta’s scientific camera Osiris showed a jet of gas and dust emerging from the side of the “neck” of material that joins the comet’s two lobes.
Scientists estimated that material in the jet was travelling at 10 metres per second, or possibly much faster.
Dr Carsten Guttler, Osiris team member at the Max Planck Institute for Solar System Research in Gottingen, Germany, said: “This is the brightest jet we’ve seen so far. Usually the jets are quite faint compared to the nucleus and we need to stretch the contrast of the images to make them visible, but this one is brighter than the nucleus.”
Measurements showed that after the outburst, levels of carbon dioxide around the comet doubled, while the amount of methane went up four times.
Dr Kathrin Altwegg, another Rosetta scientist at the University of Bern in Germany, said: “We ... see hints of heavy organic material after the outburst that might be related to the ejected dust.”
A 500-metre-long fracture has already been identified in the neck where a break could occur as interior forces build up when the temperatures continue to rise.
If the rupture happens, scientists expect to receive striking images back from the mission’s equipment.