-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
That is bandwidth at your iPad which impacted by your WiFi, what does the advanced test show?
Is the bolded part really true though? There‘s no contract term, right? You don’t have to pay anything. If you don’t like the deal then don’t take it. If enough people don’t take it then the price goes down.
Starlink is approaching profitability.
SpaceX President says Starlink had a 'cash flow positive quarter' & is on track to 'make money' in 2023
Last edited by a moderator:
General consensus from insiders is that statement is pretty flat beyond fluffing up the next raise. It's clear that more than just water-treading profitability is really contingent on SS becoming operational--that's why Mark moved from Redmond to Brownsville after all. But, as we've discussed plenty in the past there's still some serious optimism on customer base from starlink to get anywhere close to the aspirational profitability the fanbase thinks is coming.
Last edited by a moderator:
Another update from SpaceX
Argon Hall thruster tech specs:
- 170 mN thrust
- 2500 s specific impulse
- 50% total efficiency
- 4.2 kW power
- 2.1 kg mass
- Center mounted cathode
Argon Hall thruster tech specs:
- 170 mN thrust
- 2500 s specific impulse
- 50% total efficiency
- 4.2 kW power
- 2.1 kg mass
- Center mounted cathode
So... am I correct that 170mN is ~0.038 lbs of force?
That's my understanding. With the ISP of 2500, they only use 0.0000152 lbs of Argon per second of operation.
Getting to orbit favors thrust, maneuvering in orbit for a long time favors isp.
Yeah, ION is the "long haul" thruster slow and steady wins the race.
Wow... 1.5 hundred-thousandth of a pound per second. So 18.5 hours of thrust for every pound of argon they carry at full thrust.
It also happens that 0.038 (the approximate rounded # I used) divided by your ISP number is exactly 25,000. lol
So... it takes 4.2kW to accelerate the argon ions such that they generate 25,000 the mass of the medium in thrust.
That's very cool.
I think you lost a decimal place, my number is 0.038 / isp
But yeah, isp is the time than an engine can produce X thrust using X amount of fuel. Exhaust velocity is 24.5 km/sec ! So SpaceX is going to be putting kgs of Argon into highly elliptical orbits.
I did fat finger... my bad.I think you lost a decimal place, my number is 0.038 / isp
But yeah, isp is the time than an engine can produce X thrust using X amount of fuel. Exhaust velocity is 24.5 km/sec ! So SpaceX is going to be putting kgs of Argon into highly elliptical orbits.
That more or less compares to the BHT-6000 from Busek, who are emerging as industry leaders (especially with the Russian space industry fallout--Fakel was long the industry leader for supplying GEO hall thrusters). Given the very low mass on the SX unit I'd guess total impulse is less favorable than the 6000's [proportional] number, though is also likely that the line items that make up the mass rack-ups are not apples-to-apples so its hard to say by how much. The 6000 is also built for longer and higher orbit missions (Artemis, and I think some upcoming GEOs), where the SX unit really only needs to push around sats in low-mid LEO and so doesn't need as much total impulse.
FWIW, The center mounted cathode is kinda where everyone is going in the in EP thruster space, as erosion of the cathode (and ultimately, hard failure) is one of the major life limiting aspects of a hall thruster. A center cathode is a bit more complicated packaging than a side mount cathode but it ends up being more efficient overall, plus it's a little easier to manage cathode erosion.
Also FTR, on orbit Onewebs have BHT-350's running on Kr. Presumably the launch set Vlad pirated when he closed the borders do to...or at least did, before his cronies (I assume by now) took them apart to reverse engineer the technology...
Isn't total impulse dependant on the propellant mass, not thruster mass?
Is 2.1 kg wet mass? SpaceX calls out thrusters, so it seems separate.
Sorry, didn't close the point on that one. The point was that, at least to a degree, erosion can be mitigated by mass (more stuff in the way to erode) and since erosion is a major life limiter, erosion-to-failure has a significant influence on total impulse.
2.1kg is just the thruster mass. Main point there is that it's hard for me to fathom proper apples-to-apples mass rack up vs a ~7kg BHT-1500 or a ~12kg BHT-6000.
Proper V2's are likely going to have a few hundred kg of propellant. I'd guess the V1's and mini V2's are probably in the <50kg range and maybe even less because they're so low. OW's probably have 10-20kg, but they're pretty high.
dhanson865
Well-Known Member
"Due to a space weather concern, now targeting no earlier than 6:13 p.m. ET for today’s launch of 21 second-generation Starlink satellites from Florida"
Since the prior launch was 53 version 1.6 sats, I guess we can say the 2.0 Mini sats are about 2.5x the mass of a 1.6 sat.
It's a very rough figure because 51 and 53 have been used in recent launches, so it could be in the 2.4x to 2.55x range based on that, and there is room for it to have a partially unused weight limit so it could be slightly outside that range.
Still I think ~2.5x is a good conversational number.
Since the prior launch was 53 version 1.6 sats, I guess we can say the 2.0 Mini sats are about 2.5x the mass of a 1.6 sat.
It's a very rough figure because 51 and 53 have been used in recent launches, so it could be in the 2.4x to 2.55x range based on that, and there is room for it to have a partially unused weight limit so it could be slightly outside that range.
Still I think ~2.5x is a good conversational number.
