Brotoro Posted February 27, 2023 Share Posted February 27, 2023 (edited) I thought they said earlier that there is another window tomorrow. Or did they get too far into the count for a tomorrow turnaround? Edited February 27, 2023 by Brotoro Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 (edited) 5 minutes ago, Brotoro said: Not going to space today. Not Dragon, anyway. The youtube link is hosed, but there's a Starlink from the Cape, and another from VSFB tomorrow Feb. 27Falcon 9 • Starlink 6-1 Launch time: 1838 GMT (1:38 p.m. EST) Launch site: SLC-40, Cape Canaveral Space Force Station, Florida CA launch a little later at 5:15 EST Edited February 27, 2023 by tater Quote Link to comment Share on other sites More sharing options...
Spaceception Posted February 27, 2023 Share Posted February 27, 2023 I'm on my phone right now, but if you guys are interested, SpaceX posted the ion engine performance on their Twitter a few hours after the initial tweets. https://twitter.com/SpaceX/status/1629948869239873538?t=8QxDsPU97Cq9ZnckdMWgLw&s=19 In case it doesn't embed 170 mN thrust 2500s specific impulse 50% total efficiency 4.2 kW engine power 2.1 kg mass Center mounted cathode Quote Link to comment Share on other sites More sharing options...
AckSed Posted February 27, 2023 Share Posted February 27, 2023 (edited) 55 minutes ago, Spaceception said: 170 mN thrust 2500s specific impulse 50% total efficiency 4.2 kW engine power 2.1 kg mass Center mounted cathode That is very interesting. The argon is the key takeaway: the thrust's rubbish in comparison to xenon or krypton, but it's really cheap and (say it with me) present in Mars' atmosphere. The thrust to electrical power ratio is also not world-leading either, but the mass of the thruster itself is about a sixth of the BHT-6000 HET on the Artemis Lunar Gateway for half the thrust. That's more mass that can be given over to propellant or solar panels. The lighter atoms help raise the specific impulse to something on par with other thrusters. Surprisingly, the total efficiency of your average high-power HET I saw quoted was around 55%. 50% is pretty good going. Edited February 27, 2023 by AckSed Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 The VSFB launch was pushed to tomorrow because of weather, and Crew-6 is March 2 now. Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted February 27, 2023 Share Posted February 27, 2023 (edited) And let’s not forget: Anyone ever do a Kerbal sim to the outer planets of such a mission? Robert Clark Edited February 27, 2023 by Exoscientist Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted February 27, 2023 Share Posted February 27, 2023 31 minutes ago, Exoscientist said: And let’s not forget: Anyone ever do a Kerbal sim to the outer planets of such a mission? Kerbal sim isn't really necessary; we can do the math easily enough. Elon is talking about a velocity kick from an eccentric orbit...let's say GTO for the sake of simplicity (much higher and phasing gets froggy). Starlinks are on the order of 260 kg, but let's assume modifications bring them up to 300 kg (they're going to need some sort of attitude control and increased solar capacity since they won't be in LEO). Interpreting "a few dozen" as 40, that's 12 tonnes of payload. Total dV on the expendable Starship would be 11.7 km/s. Add the 2.3 km/s you get from your GTO staging orbit and that's a total of 14 km/s to play with (relative to LEO). That's a lot. But what would you do with it? This feels like a throwaway tweet by Musk, given that Starlink satellites don't have imaging or other science systems or anything else to contribute, and their solar power makes them pretty useless beyond 2 AU. The New Horizons spacecraft had a launch mass of 478 kg, not much more than a modified Starlink. With the same mass budget, you could launch no less than 25 New Horizons clones all over the solar system, if you wanted. Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 (edited) 1 hour ago, Exoscientist said: Anyone ever do a Kerbal sim to the outer planets of such a mission? Expended SH gives you ~250t of payload in LEO. That's residual props plus those starlinks. Call them 500kg (modified heavily) for slop. A few dozen is > a couple dozen, so 36 starlinks, that's 18t. That means the expendable upper stage has 5997 m/s. Let's drop the mass of each starlink by a hair, and call it 6 km/s Then you have 1.6km/s for each sat. Escape from LEO is 3.22 km/s, so these guys head off to wherever still on SS with 2.78 km/s to play with, then their own dv. You need ~2.7 km/s to go from Vesc to low Mars orbit, so even with losses, the expendable stage could place the 3 dozen sats in LMO, and they could then use their thrusters to spread out (some doing a plane change). EDIT: I realize I have no idea how much props the sats hold, so no dv Edited February 27, 2023 by tater Quote Link to comment Share on other sites More sharing options...
zolotiyeruki Posted February 27, 2023 Share Posted February 27, 2023 22 hours ago, tater said: (wonder if it can dissipate charge separations in the first place, reducing leaders, and hence strikes) Most people don't realize that charge dissipation is actually a lightning rod's primary method of protection. Charges like to congregate on a sharp point, and that makes it easier for them to hop off into the air, reducing the potential between clouds and ground. If it doesn't work out, then yeah, the cables provide a current path to ground. Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted February 27, 2023 Share Posted February 27, 2023 19 minutes ago, sevenperforce said: Kerbal sim isn't really necessary; we can do the math easily enough. Elon is talking about a velocity kick from an eccentric orbit...let's say GTO for the sake of simplicity (much higher and phasing gets froggy). Starlinks are on the order of 260 kg, but let's assume modifications bring them up to 300 kg (they're going to need some sort of attitude control and increased solar capacity since they won't be in LEO). Interpreting "a few dozen" as 40, that's 12 tonnes of payload. Total dV on the expendable Starship would be 11.7 km/s. Add the 2.3 km/s you get from your GTO staging orbit and that's a total of 14 km/s to play with (relative to LEO). That's a lot. But what would you do with it? This feels like a throwaway tweet by Musk, given that Starlink satellites don't have imaging or other science systems or anything else to contribute, and their solar power makes them pretty useless beyond 2 AU. The New Horizons spacecraft had a launch mass of 478 kg, not much more than a modified Starlink. With the same mass budget, you could launch no less than 25 New Horizons clones all over the solar system, if you wanted. The difference is speed. It took 10 yeas for New Horizons to each Pluto. The high Isp of the ion engines would allow them to get to one of the outer planets or dwarf planets more quickly. The high Isp also means they could slow down to actually go into obit. Bob Clark Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 14 minutes ago, Exoscientist said: The difference is speed. It took 10 yeas for New Horizons to each Pluto. The high Isp of the ion engines would allow them to get to one of the outer planets or dwarf planets more quickly. The high Isp also means they could slow down to actually go into obit. I forgot to do the math on the new thrusters. Assume my 500kg modified starlink, where 300kg is sat, and 200kg is props. That sat has 12.5 km/s of dv, starting from having been given Vesc and then some. ~15 km/s post escape. Quote Link to comment Share on other sites More sharing options...
AckSed Posted February 27, 2023 Share Posted February 27, 2023 1 hour ago, sevenperforce said: But what would you do with it? This feels like a throwaway tweet by Musk, given that Starlink satellites don't have imaging or other science systems or anything else to contribute, and their solar power makes them pretty useless beyond 2 AU. It is a throwaway tweet, but according to Casey Handmer, the phased arrays and software-defined radios on Starlink satellites already compensate for atmospheric distortion, and are a software upgrade away from using that to predict weather and perform synthetic aperture radar. I don't know how deeply it could penetrate other atmospheres but measuring the weather and imaging the surface of, say, Venus in resolution comparable to other Earth-imaging sats would be valuable science points. I'm sure we could stick a GoPro on each of them as well. The constellation might need a specially-built base station to store and transmit the findings back to Earth, and I'm not sure what radiation-hardening might be needed outside of Earth's magnetosphere, but there it is. Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 Modify a few with high-gains, or add solar to all of them for this use case. That's why I assumed a doubling of mass. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted February 27, 2023 Share Posted February 27, 2023 Starlink launch music Coverage is live. T minus 6 minutes. Starlink V2 minis. Booster's 3rd flight. Quote Link to comment Share on other sites More sharing options...
Brotoro Posted February 27, 2023 Share Posted February 27, 2023 Liftoff. Staging good. Interesting view of fairing separation, looking backward from somewhere on top of the Starlink stack? Starlink service is live in Rowanda... but not yet at my house. Interesting shadow of booster on Nitrogen jet gas Entry burn successful Landing! Nice views from both booster and drone ship. Quote Link to comment Share on other sites More sharing options...
Minmus Taster Posted February 27, 2023 Share Posted February 27, 2023 Amazing footage! Quote Link to comment Share on other sites More sharing options...
Brotoro Posted February 27, 2023 Share Posted February 27, 2023 21 Starlink V2 minis are now in orbit. Quote Link to comment Share on other sites More sharing options...
tater Posted February 27, 2023 Share Posted February 27, 2023 Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted February 28, 2023 Share Posted February 28, 2023 3 hours ago, Exoscientist said: The high Isp of the ion engines would allow them to get to one of the outer planets or dwarf planets more quickly. The high Isp also means they could slow down to actually go into obit. Aside from the issue of only having solar power in the outer solar system… Quote Link to comment Share on other sites More sharing options...
tater Posted February 28, 2023 Share Posted February 28, 2023 (edited) 6 hours ago, Exoscientist said: The difference is speed. It took 10 yeas for New Horizons to each Pluto. The high Isp of the ion engines would allow them to get to one of the outer planets or dwarf planets more quickly. The high Isp also means they could slow down to actually go into obit. The higher thrust than the current Starlink krypton thrusters would help here, not the Isp in terms of mission time (vs propellant cost). They can have plenty of dv, but they are stuck doing constant, low-thrust trajectories. These low-thrust trajectories are spirals, vs the ellipse of a Hohmann transfer where the dv is expended at periapsis, raising the apoapsis of the orbit. This results in multiple orbital periods for a given transfer, each slightly larger (and longer) than the last. So it might take a couple years to get to Mars, and a few more to get to Jupiter. That said, the expended SS/SH mission has excess dv in SS beyond escape, so it's a hybrid trajectory. In fact, there's enough from SS to easily throw all towards Mars. They can then slingshot for their final outer solar system missions. I should add that as @StrandedonEarth points out, the solar panels will drop off with increased distance from the sun. Part of "heavily modified" must be 2, 4, or even 6X the solar arrays, and even that starts failing the farther out we are. Pluto, etc requires nuclear (RTG or a small reactor). Edited February 28, 2023 by tater Quote Link to comment Share on other sites More sharing options...
Beccab Posted February 28, 2023 Share Posted February 28, 2023 Quote Link to comment Share on other sites More sharing options...
tater Posted February 28, 2023 Share Posted February 28, 2023 Looks like they've reduced some orbital debris by keeping the rods attached to stage 2. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted February 28, 2023 Share Posted February 28, 2023 6 hours ago, Beccab said: Did they seriously just launch the whole stack by just moving a single arm out of the way? Very Kerbal! Quote Link to comment Share on other sites More sharing options...
RCgothic Posted February 28, 2023 Share Posted February 28, 2023 1 hour ago, JoeSchmuckatelli said: Did they seriously just launch the whole stack by just moving a single arm out of the way? Very Kerbal! I *think* there's probably an arm on the opposite side. Quote Link to comment Share on other sites More sharing options...
Exoscientist Posted February 28, 2023 Share Posted February 28, 2023 There is speculation on the new Starship nosecone: SInce ship 26 will be expendable maybe the new nose cone is without header tanks in the nose. Robert Clark Quote Link to comment Share on other sites More sharing options...
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