Roscosmos is not going to waste Progress spacecraft docked to International Space Station and let it burn in atmosphere - it has science mission !
Good science experiment is such experiment which could be performed for free - surely falling apple which was spotted by Isaac Newton was not very expensive. Unfortunately in space, every experiment costs a lot. But sometimes there are exceptions - good example is Progress robotic spacecraft and Izgib research program. After resupply mission, Progress remains docked to ISS and after certain period of time it is filled by crew with trash and things which are unnecessary. After undocking, it is performing maneuvers to reach correct position for for reentry. After reaching dense layers of atmosphere, spacecraft is burning and parts which were not fully burned are falling into Ocean. Not this time - according to Tass news agency, Roscosmos planned to utilize Progress which remains docked to Zvezda module to science experiment.
Progress-M29M was launched in 152nd mission of Progress on 1 October 2015 and docked to ISS on 2 October 2015. It was planned to keep spacecraft docked to Zvezda module until 29th March 2016. Roscosmos announced that after undocking Progress on 29th March 2016 and reaching safe distance from ISS it will start lasting seven days series of experiments. It is interesting that it will be possible only with onboard instruments of Progress - no additional scientific payload on M-29M will be used. Experiment will be performed with support of Mission Control Center-one of the departments of research in Central Research Institute of Machine Building, and RKK Energia. Experiment purpose is research on gravity conditions and micro accelerations on International Space Station especially influence on liquids and gases. Gathered data will help in creating most adequate models describing ISS gravity environment. Progress will perform various maneuvers around ISS to measure its influence on microgravity inside ISS. Only science payload utilized during Izgib is Dakon-M, weighing 11.56 kg convection sensor installed on the Zvezda module (Dakon device was also installed on Mir space station). Additional data will be gathered by ISS and Progress onboard sensors: gyroscopic angular rate vector meter, accelerometers normally used by navigation and control systems, onboard micro acceleration sensors and angular velocity sensors; Also SAMS and MAMS accelerometers installed on Destiny laboratory module will gather micro acceleration data. Telemetry data will be transferred to RKA Mission Control Center in Koryolov, Russia.
On picture above: flame in microgravity conditions.