Author Topic: Israeli robotic lunar lander  (Read 1003 times)

Offline JayUtah

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Re: Israeli robotic lunar lander
« Reply #15 on: February 24, 2019, 04:52:27 PM »
Isn't that known as the Oberth Manoeuvre?  You get more bang for your buck at high velocity than low.

Yep.
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Offline ka9q

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Re: Israeli robotic lunar lander
« Reply #16 on: February 25, 2019, 06:20:34 PM »
Incidentally, how is it that multiple short burns to raise the apogee are more efficient than a single longer one? Is it that the efficiency of the burn is greatest when the spacecraft is closest to perigee, and this efficiency drops off considerably even minutes either side of perigee?
This assumes an instantaneous burn. If the required burn time is too long, it might be more efficient to split it up to a bunch of shorter ones.

Offline ka9q

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Re: Israeli robotic lunar lander
« Reply #17 on: February 25, 2019, 06:24:57 PM »
I haven't studied the Beresheet trajectory, but another consideration is that it is more efficient to do plane changes at apogee. If one is necessary along with apogee raising, it might be more efficient to establish an intermediate apogee to do the plane change.

Offline bknight

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Re: Israeli robotic lunar lander
« Reply #18 on: February 26, 2019, 12:26:49 PM »
First burn was successful raising the perigee to 600 Km.

https://spacenews.com/spaceil-lunar-lander-makes-first-post-launch-maneuvers/
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Offline bknight

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Re: Israeli robotic lunar lander
« Reply #19 on: March 01, 2019, 01:12:34 PM »
A second burn successfully completed after a aborted attempt on Monday.  The new Apogee is 131000 Km.

https://www.space.com/israel-moon-lander-beresheet-engine-firing.html
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Offline bknight

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Re: Israeli robotic lunar lander
« Reply #20 on: March 21, 2019, 07:42:14 AM »
A final burn has been completed for the craft to enter an orbit of the Moon.

https://www.israelnationalnews.com/News/News.aspx/260690
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Offline raven

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Re: Israeli robotic lunar lander
« Reply #21 on: March 21, 2019, 11:23:29 PM »
A final burn has been completed for the craft to enter an orbit of the Moon.

https://www.israelnationalnews.com/News/News.aspx/260690
"Israel’s first spacecraft performed a special maneuver Wednesday night, aimed at putting the lunar lander into position to achieve a stable lunar orbit."
"Israel’s first spacecraft."
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