dogslayeggs @ dogslayeggs @lemmy.world

Posts

4

Comments

1,517

Joined

2 yr. ago

That's all true, but there are many people who are planning to retire soon. There are also people who a college saving fund for their kids that is tied to the market, so now their kid's college fund is much smaller. Depending on how much the market drops, it could really screw over a crop of kids trying to go to school in the near future with other kids their own age.

Better than ballistic dead reckoning, yes. I'm not sure whether it is better or worse than star trackers plus inertial navigation units at that time scale (INUs drift over time and need to be recalibrated every so often to fix that drift, but I really don't know how accurate star trackers are for position since I only use them for attitude measurement).

Mars was mentioned because it was written by a journalist, not a scientist. If you read all the quotes from NASA and the Italian agency, they only mention the Moon. Mars is too far away for any use of Earth/Moon/Lagrange based PNT satellites.

For lunar applications, power isn't really the limiting factor. It is the one factor we weren't sure about before this mission, so we figured that out. Another factor is geometry, with the long distances to the moon but small distances between satellites. A final factor is antenna directions and gain patterns. GPS antennas are facing the Earth and directional to the Earth (though there is a VERY tiny omnidirectional on the rear). The main antennas shove most of their power to the Earth's surface and have a small amount that leaks to the sides away from Earth. This mission used those side lobes, but because of the distances involved you don't see very many side lobes out at the moon. Even at GEO, space based receivers are only seeing a small number of satellites at a time because the Earth blocks most of the signal.

If NASA wanted a real PNT solution on the moon, they would need to have dedicated satellites with moon facing antennas. Even better would be moon surface repeaters with large antennas.

Nothing to prevent it except money. The issue with PNT satellites around Mars is how many satellites would have to be sent (smaller planet and less accuracy needed, so maybe we could get away with 12 instead of 24), plus the ground command and control stations plus monitoring stations. The ground part is probably the most critical piece of why GPS is so accurate, and I'm not sure we could do that from Earth. Definitely couldn't do the monitoring from Earth.

We'd have to be able to build an accurate ephemeris table for the Mars satellites, have accurate clock updates, monitor the signals being transmitted to do updates, etc. While we could do the commanding and controlling from Earth, I don't know if we could do the things from Earth that make GPS accurate. So not only would we have to send 12 satellites to Mars, we'd have to build monitoring stations on Mars to do the ground portion. Technically doable, just not financially feasible when we have star trackers and other navigation systems that work well enough for now.

I work on GPS satellites and am on the team working to define the next generation of GPS satellites. The beacon idea you are talking about is a terrestrial augmentation system. We have that here on Earth already, and it's critical infrastructure. On the moon, you could add nodes that receive GPS time and are used as a navigation aid on the moon. I doubt we would spend the money to put a GPS satellite at a Lagrange point anytime soon, since the benefits would be minimal for a single satellite. There is a lot more military interest in cis-lunar missions, though, so there might be benefits later. Repeater nodes on the moon's surface might be worth it, if we start doing more missions there.

Lagrange points are also pretty far away (the closest one is 1 million miles away, while the moon is 238,000 miles away. Current GPS satellites barely have the power to send a usable signal to the moon. To get a usable signal from Lagrange distances, the power would have to be much much higher (power drops as a square of distance. There's also the issue of building a satellite that lasts long enough in that radiation environment to make it worth it, since launching a satellite that big that far away is expensive. And that still would only help on the way to Mars, since Mars is another 99 million more miles past that (extremely rough numbers, since the average is 140 million miles from Earth but closest is 34 million miles and I have no idea what the distances would be to L4/L5 points).

They run the FAFSA student aid application system and manage trillions of dollars of student loans (Pell grants, etc). They provide guidance and funding to state education systems.

Dismantling it will cause chaos in the student loan world. Who now owns the debt? (likely given to friends of Trump to get rich off of) Who approves new debt? (likely private loan firms who charge higher rates and don't approve high risk loans) Who will manage the existing network of thousands of colleges to help get aid to students? (likely nobody)

Dismantling it also allows Republican states to further implement religious education and scrubbing from education curricula anything that isn't about straight, white people doing good things.

They were only able to receive signals from the bare minimum to achieve a solution (4 GPS and 1 Galileo). Their achieved accuracy was +/- 1.5km and +/- 2m/s. That is good enough in astronomic scales to get you to a planet, but it isn't going to help failed landings or autonomous landings.

I don't think there was any new tech involved, just a receiver put on a moon lander to see if it could detect signals. And this won't really do anything for Mars for two reasons: 1) the signal strength would be too small for any reasonable antenna to detect GPS L1/L5 at Mars distances, and 2) the distance would make the geometry be unusable to trilaterate a solution... think about a triangle where two lengths are 100 million miles and the third length is 100 miles. That is a completely worthless geometry for trilateration of a position solution. Even if we could somehow detect a GPS signal at Mars, best case is we get atomic clock time.

It requires an act of Congress to dismantle it completely, so we're about to see just how much the R's in Congress either have bought into Trump's vision or think there is value in keeping his support. It's one thing to not say anything when a bunch of normal people are fired. It's a different thing to publicly vote to dismantle something normal need and care about.

I'm shocked, shocked I tell you.

No, it isn't. Eugenics is about changing genetic distributions, and low-income is not a genetically passed trait. If you ONLY gave the free condoms to black students at those schools and encouraged the white students to not use condoms, then I'd agree with you. Or if you only gave the condoms to kids who weren't getting good grades or were bad at sports, then I'd agree with you.

But blindly giving out condoms to a large population without any look at genetics is not eugenics.

We couldn't watch it. We usually watch parts or all of the State of the Union and are pretty politically inclined, but we just could not listen to him say more than one sentence without wanting to break our TV. I haven't heard anyone at the office talking about it, either.

I'm guessing only his fans watched it, so of course it had high approval from those who watched it.

This sounds to me like a way to sell critical national infrastructure to private businesses. Just one more way to weaken the US as a country in order for the rich people to make more money in the short term.

I have no idea what the solution is, but whatever the Democrats are doing right now isn't working. I would LOVE for them to move further left AND win because of it. It would not only take the country in the right direction but would also feel less like the country is permanently fucked up. I would ACCEPT for them to move further right in order to win back control. I wouldn't be happy, but at least we could get some sane people back in control.

This country has 100 million people who don't care enough about anything to bother voting at all, 80 million of whom aren't even registered to vote even though they are eligible. I can't even imagine what it would be like to see what's going on right now and not care about voting to fix it. There are 70 million people who are HAPPY about what Trump is doing. Our country is fucked if 170 million people are either happy or don't care about what is happening.

Did you miss the bit where you said,

I straight don’t buy that these results accurately reflect the opinion of non boomer voters.

And yes, we are straight fucked already.

There's a difference between taking the man seriously and taking the impacts of the man's actions seriously.

You can put Caddyshack-era Bill Murray in the presidency and not take him seriously, but if he starts making his predictable nutcase ramblings into multi-daily Executive Orders then you better take that seriously.

I don't know if any thing in that video looked even remotely realistic, except maybe the lame handstand ride.

There are millions of Americans who really want a non-crazy conservative to vote for. There are millions of people who just want to have a non-crazy person win an election, so their idea is that the only way the opposition to crazy Republicans to be able to win over some of those people on the right is by moving closer to them. They just want to stop losing to the crazies. There are millions who are OK with gay people but hate that the government spends too much money on everything.

America is a very conservative country, and even the Democrats are basically very conservative.

Those people who complained that the Democrats would have beat Trump if they had just moved more left have no idea how much the rest of the country doesn't feel like them.

You know what would help end the war in Ukraine? Letting Russia keep all their money and having no repercussions for their actions. That should do the trick.

That was one of the most disgusting and rage-inducing videos I've ever seen. I would not have been able to restrain myself from punching Trump in the fucking nose if he had talked to me like that. I'm not a tough guy or violent in any way, and the Secret Service would have killed me, but the way he yells such insulting things at a world leader who is trying to save millions of lives... holy crap. And then Vance jumps in and claims he never said Thank You. I would've kicked him in the nuts and said, "thank you, now I feel better."

This was a setup from the get go. They had no intention of signing any deal. This was all to get him in front of cameras with them so they could piss on his face and act like tough guys.

Because there is very little to be gained by those American billionaires in this issue, so why would he pull this insane stunt? There is a lot to be gained by Russia, though. There is also the constant stream of verbal praise Trump has for Putin that he doesn't show for any other person except maybe Musk (who is the richest person on the planet).