ESA has announced the date upon which missionoperators will crash the Rosetta spacecraft into the surface of thecomet 67P/Churyumov–Gerasimenko. Unlike its now-sleepingcompanion, the Philae lander, there is no hope that once thespacecraft touches down on the surface of 67P, the science teamwill be able to re-establish contact with the legendary probe.
After arriving in orbit around 67P in August 2014,Rosetta and Philae have, and continue to provide ground-breaking insights regarding the enigmatic nature of wandering comets. It hasbeen a mission of impressive feats and intense periods of nervous anticipation.
ESA was not slow to pull on the heartstrings,releasing cartoon after cartoon that succeeded in anthropomorphizingthe remote explorers. The combination of a well-executed publicawareness campaign coupled with the ambitious nature of the endeavoursucceeded in capturing the public's attention in a way that fewunmanned missions have managed before.
Unfortunately, as with all great things, Rosetta'smission must come to an end. The spacecraft is currently riding 67Pout towards the orbit of Jupiter. At its furthest point, the probewill be some 850 million km (553 million miles) distant from the Sun.At this range, Rosetta will lack the bandwidth to transmit scientificdata, and will be unable to gather enough precious starlight to powerits systems. Returning the spacecraft to a state of hibernation isnot an option, as the probe's heaters would almost certainly fail,preventing it from ever awakening.
Instead of risking this almost certain anaemicdemise, the Rosetta team have elected to have Rosetta go out in ablaze of glory, by sending to probe to join Philae on the surface of67P, with a preliminary date set for the 30th ofSeptember. According to Rosetta's handlers, the spacecraft's descentis likely to be far more challenging than that faced by Philae inNovember 2014.
The danger forRosetta is not the force of landing, but rather the influence of thecomet during the final six weeks prior to the collision. During thisperiod, the probe will be more susceptible to the gravitationalinfluence of the irregularly shaped comet. This could lead todeviations in Rosetta's trajectory – a significant problem for aspacecraft traversing a tight, eccentric orbit around anunpredictable comet. To keep Rosetta safe, mission operators will beforced to upload course corrections on a more regular basis.
The team is setto begin tweaking Rosetta's trajectory starting in August, with afinal course correction scheduled for 12 hours before impact. If allgoes well, Rosetta will touch down on 67P at a mere 50 cm per second– roughly half the speed at which Philae first collided with thecomet. On the way down, Rosetta will be firing on all cylinders,collecting as much high-res imagery and scientific data as possible,before ending its 12-year journey in space by coming to rest on thesurface of the comet it had spent its life documenting.
"We're trying to squeeze as many observationsin as possible before we run out of solar power," comments MattTaylor, ESA Rosetta project scientist. "30 September will mark theend of spacecraft operations, but the beginning of the phase wherethe full focus of the teams will be on science. That is what theRosetta mission was launched for and we have years of work ahead ofus, thoroughly analysing its data."
Source: ESA