NEW DELHI: Isro chairman V Narayanan said on Saturday that the country is preparing for the first uncrewed Gaganyaan mission, advancing Chandrayaan-4, a lunar sample return mission, and Chandrayaan-5, a joint long-duration mission with Japan involving a heavier rover.Delivering the 17th Air Chief Marshal L M Katre Memorial Lecture in Karnataka, Isro chief said, “We are now working on the first uncrewed mission this year. Then once we review the result, we’ll come back to the crewed mission.” He added, “Gaganyaan is a technology-intensive mission. We have to do the human-rating of the vehicle … before sending actual human beings, we have to do 3 uncrewed missions, and we are working towards the first uncrewed mission. You will come to know about the dates very shortly …”On the lunar missions, Narayanan said Chandrayaan-4 will be India’s first lunar sample return mission, while Chandrayaan-5, to be undertaken jointly with Japan, will deploy a 350-kg rover capable of operating for nearly 100 days, compared with the 25-kg rover and 14-day operational life of Chandrayaan-3. On India’s cryogenic engine programme, he said technology denial had ultimately strengthened indigenous capabilities. “Today, I thank the countries that denied us the technology. Today we have developed three cryogenic propulsion systems,” he said. Referring to the recent successful hot test of the semi-cryogenic engine power head test article (PHTA) at a thrust level of 175 tonnes, Narayanan said, “A test that was conducted, excluding the thrust chamber … we have taken close to 90% of the thrust load … it was a major achievement and milestone, and now we are getting ready for the engine test … satellites are ready, and we are working on that, an exact date will be provided soon ...”Meanwhile, aerospace engineer N Jayan, who led the development of the indigenous CE20 cryogenic engine that powers India’s LVM3 heavy-lift launch vehicle, has been appointed director of the Liquid Propulsion Systems Centre (LPSC).