Juno Earth Flyby Today
Juno Prepares For Earth Flyby on Wednesday
“The flyby will function as a gravity assist for Juno, with Earth’s gravity accelerating the solar-powered spacecraft’s velocity by 16,330 miles per hour. NASA launched Juno to an area just past Mars, then two main engine burns executed a year ago maneuvered it back around toward Earth. The purpose of using a gravity assist to get Juno on its way to Jupiter is one of cost.”
– Flyby info, SwRI
– Earth Image from JunoCam
Although the mission will prove impressively that it is possible to operate a probe with photovoltaic power only at the orbit of jupiter, it still isn’t clear that this is more practical than the usual strategy of using an RTG
I’m sure others will be able to better comment to this question…but if the J-2X had been finished and certified, would NASA have been able to use a launch vehicle with the J-2X as the final, Earth departure stage, to send the Juno on a direct trajectory to Jupiter?
No, because there is not currently a core stage capable of lifting the huge upper stage tanks that J-2X needs to operate effectively.