Chennai, Dec 29 (Reporter) Aiming to end 2024 on a high, the 25-hour Countdown for Indian Space Research Organisation (ISRO)'s twin record mission--one on first ever space docking technology --docking and undocking series involving two Spadex satellites--and the other on 24 innovative scientific experiments as part of POEM-4 involving the fourth Stage of PSLV, onboard the PSLV-C60 launch vehicle, began at SDSC, SHAR Range, on Sunday night. The commencement of the countdown at 2058 hrs was confirmed to UNI tonight. The PSLV-C60 Spadex Mission, carrying two payloads Spadex-A and Spadex-B, both weighing 220 kg each, will lift off from the First Launch Pad at the spaceport of Sriharikota at 2158 hrs on Monday night. This mission would enhance ISRO's its operational flexibility and expand its mission horizons. ISRO sources on Sunday said the countdown for the mission began at 2058 hrs at SDSC Centre during which propellant filling operations will be carried out in the four stage vehicle. This would be 62nd flight of PSLV and the 18th core alone configuration, without the four strap-on motors. ISRO is keen to sign off the year 2024 on a high with the successful maiden space docking demonstration as this pathbreaking Mission will propel India to become the fourth country in the world in mastering the complex space docking technology. Apart from the Spadex launch comprising two satellites--Chaser and Target for space docking demonstration, this would be a historic and groundbreaking mission as ISRO will script history by deploying a record 24 scientific experiments into space aboard the PSLV Orbital Experiment Module-4 (POEM-4) along with the SpaDeX mission. ISRO said PS4-Orbital Experiment Module (POEM) revolutionizes space tech!. "With 24 cutting-edge R&D payloads (14 from ISRO, 10 from academia/startups), it pushes boundaries in biological experiments, robotics, SAR imaging, AI labs, & more...A giant leap for science & innovation", it said. The success of Spadex mission will enable India join a select group of space faring nations in mastering the space docking technology which will give a major fillip for future missions like Chandrayaan-4 and first ever human space flight Gaganyaan. The SpaDeX spacecraft was designed and realized by the UR Rao Satellite Centre (URSC) with the support of other ISRO centers (VSSC, LPSC, SAC, IISU, and LEOS). SpaDeX Mission is to demonstrate the first ever technology needed for rendezvous, docking, and undocking of two small spacecraft (SDX01, which is the Chaser, and SDX02, the Target, nominally) and they would be launched in a low-Earth circular orbit. SpaDeX mission is a cost-effective technology demonstrator mission for the demonstration of in-space docking using two small spacecraft launched by PSLV. This technology is essential for India’s space ambitions such as Indian on Moon, sample return from the Moon, the building and operation of Bharatiya Antariksh Station (BAS), etc. In-space docking technology is essential when multiple rocket launches are required to achieve common mission objectives. "Through this mission, India is marching towards becoming the fourth country in the world to have space docking technology", ISRO said...////...