12 thoughts on “The Parker Solar Probe”

  1. I saw some discussion at NSF.com suggesting that the Falcon Heavy could not make this launch, because the spacecraft needs the extra kick from the Star 48 solid third stage, and SpaceX doesn’t use solid motors.

    I’m not sure I understand that. I assume Falcon Heavy could send a probe to the vicinity of Venus, and then the gravitational assist sends it closer to the Sun. I’m not a rocket scientist, so what am I missing?

      1. SpaceX doesn’t believe in using solids. They could, but they never have, and they don’t have the processing facilities.

        But the first stage of Falcon Heavy is more powerful than the first stage Delta IV Heavy, and the second stage has greater thrust than Delta IV Heavy’s second stage, although the latter can burn much longer.

        So I don’t know.

    1. The DIVH bees the star 48 too, and it’s mated to the spacecraft and inside the payload fairing (and thus considered part of the payload rather than the LV,).

      I’m not sure that Falcon 9H could achieve the needed C3 (53!!! Which I think will be a record) due to its lower ISP, but it’d be close. The fact their was official talk of SpaceX doing this launch seems to me to indicate it was possible.

      My guess; SpaceX is not set up to handle solids, and has never done so. Also, FH block 5 has never flown. So DIVH got the job.

      1. SpaceX has a lot on their plate right now. It probably doesn’t make sense for them to go through the effort of engineering this one launch where the requirements might never be repeated again.

      2. You can consider the third stage as part of the payload. There’s no reason why they couldn’t launch this confguration on a Falcon Heavy.

      3. The launch contract for this mission was let long before a Falcon Heavy had ever flown. There’s no way NASA would sign a cntract for a high priority mssion like this on an unproven rocket.

    2. You can consider the third stage as part of the payload. There’s no reason why they couldn’t launch this confguration on a Falcon Heavy.

  2. So Parker launches Aug 11 and reaches Perihelion Nov 1, requiring less than 3 months and will return to Earth distance in less than another 3 month.

    So it goes from a year orbit to 1/2 year orbit due to the rocket’s delta-v and one Venus gravity assist. And from Aug 11 to sept 28 2018 [or around 45 days] it goes from Earth distance and crosses Venus distance.
    Though I don’t believe that fastest spacecraft has gone crossing two different planetary distances, but would guess it’s fastest time in terms close flybys of two planets [Earth and Venus] but it should make records in fast transits in terms crossing Venus and Mercury orbital distance and/or flyby of these two planets

  3. Larry is right on both counts:

    1) The Parker Solar Probe was first approved in 2009-10, and it signed with ULA in 2015 to employ a Delta IV Heavy launcher. (They had originally planned to use the same launch setup as New Horizons – an Atlas V 551 with an ATK Star 48 kick stage – but eventually figured out that it did not prove sufficient delta-v for the orbit they wanted.) And in 2015, Falcon heavy was not even close to flying, let alone rated for a New Frontiers-class mission, unfortunately. Delta IV Heavy was the only game in town for it when they had to decide on a launcher. It’s one thing for Arabsat to take a flyer on a launcher years ahead in its development cycle; but NASA does not work that way.

    2) The Star 48 kick stage was housed as payload, not as part of the launch vehicle. There’s no reason why, theoretically, a Falcon Heavy could not launch a payload with a Star 48 kick stage, too.

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