SpaceIL lunar lander mission - 2019 |
SpaceIL lunar lander mission - 2019 |
Sep 13 2018, 06:21 AM
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#1
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Solar System Cartographer Group: Members Posts: 10167 Joined: 5-April 05 From: Canada Member No.: 227 |
I'm setting this up in preparation for the launch of SpaceIL's lunar mission, probably early next year. They have arranged a rideshare with Spaceflight Industries on a Falcon 9 launch early in 2019. Earlier they were saying launch in December, land on the Moon in February, so now I assume the landing might be delayed until March. This mission was originally going to be part of the Google Lunar X Prize, but that of course is now gone. It might be rekindled with a different sponsor (though I doubt it).
SpaceIL is the first of the GLXP teams to actually make it to a launch. For what it's worth, I expect Astrobotic to fly as well, and I think Team Indus and PTScientists may also get off the ground. I'm hearing things about Moon Express which cause me to doubt its chances. More on landing sites shortly. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Apr 12 2019, 05:59 AM
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#2
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Junior Member Group: Members Posts: 99 Joined: 17-September 07 Member No.: 3901 |
On April 5, Space News reported that the lander fired its main engine for six minutes, slowing the spacecraft by about 1,000 kilometers per hour.
https://spacenews.com/spaceil-lander-enters-lunar-orbit/ These numbers work out to 0.77 meters per second squared acceleration, which is less than half of lunar surface gravity. Landing from a low lunar orbit needs about half of the spacecraft to be propellant, so after burning that off, the deceleration capability would still be less than lunar surface gravity. So if the reported numbers correctly represent full thrust from the main engine, there would not have been enough thrust to land. Does anyone know the correct numbers for the orbit insertion burn last week, or is it true that there simply was not enough thrust? Otherwise, what did I miss in my calculation? A million meters per hour in 6 minutes is 278 m/s in 360 s, or 0.77 m/s^2. |
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Apr 12 2019, 02:17 PM
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#3
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Junior Member Group: Members Posts: 28 Joined: 17-April 08 From: Okemos, MI, USA Member No.: 4097 |
Otherwise, what did I miss in my calculation? A million meters per hour in 6 minutes is 278 m/s in 360 s, or 0.77 m/s^2. I'm not sure you missed anything. According to the Wikipedia entry, Beresheet has a dry mass of 150kg and a Leros 2b engine capable of 407N thrust. If we assume it's near-dry at landing, that gives it 2.7 m/s^2 acceleration, which should be fine for a lunar landing. The fueled mass is more like 585kg, of which I think they'd used about 100kg of fuel at that point, which works out to 0.90 m/s^2, perhaps within the uncertainty of our napkin-based calculations. Presumably, the rest of the fuel is used up lowering the apolune and during the descent maneuver, though I haven't been able to find any clear description of the engine firing for those maneuvers. |
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