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Artemis II crew take “spectacular” image of Earth

bbc.com

351–360 of 419 posts

Re: Artemis II crew take “spectacular” image of Earth

#351

This is all we've got. We need to do a better job of preserving it.

    > We need to do a better job of preserving it.
I reject this sentiment. Ask anyone that you know who lived through the 1960s in a rich country. Their experience is nearly all the same: The air quality and environmental pollution was appalling. When my mother lived in Manhattan (New York City) in the 1960s, she would return home from work, and wipe her face with a cloth. The cloth had black streaks from all the pollution. Today, it is a different world in rich countries. They have cleaned up.

Finally: Yes, global warming is real, but the threat is different. I predict that we will far exceed the average increase in global average temperature, but we will survive. Yes, we will survive, but with some "scars".

Re: Artemis II crew take “spectacular” image of Earth

#352
post #68

Earlier quoted context omitted.

They couldn't do that for "a few bucks of nano banana credits" though. You could generate the imagery but that's only one line of evidence. A launch is easily detectable through multiple signals. Why would Russia and China and any other country with any degree of astronomic capability that the US has an adversarial relationship with just let them get away with lying to the world? Why wouldn't they take the opportunit…

How would they prove that no launch happened? There isn't conclusive evidence of an absence of launch, and if there were it would be accused as being fake and a ploy from American enemies to discredit them.

> and if there were it would be accused as being fake and a ploy from American enemies to discredit them.

Yeah so, the soviets were pretty good at dodging things like that:

https://en.wikipedia.org/wiki/1960_U-2_incident

Re: Artemis II crew take “spectacular” image of Earth

#353

This is all we've got. We need to do a better job of preserving it.

> We need to do a better job of preserving it. I reject this sentiment. Ask anyone that you know who lived through the 1960s in a rich country. Their experience is nearly all the same: The air quality and environmental pollution was appalling. When my mother lived in Manhattan (New York City) in the 1960s, she would return home from work, and wipe her face with a cloth. The cloth had black streaks from all the pollut…

We have done a lot better with faster and readily perceptible environmental problems.. from air pollution in China to acid rain killing forests and lakes in Europe. So yes, we should celebrate our successes too.

Re: Artemis II crew take “spectacular” image of Earth

#354
post #317

Earlier quoted context omitted.

the morning after the launch i just randomly went onto their livestream and one of the astronauts was asking mission control for help on also using the gopros and iPhone cameras. i guess they have some. and he was struggling at getting a properly exposed photo with those. he said they were coming out super over exposed. but the D5 was working nominally. mission control said they'd get back to them about ideas on adju…

You have to wonder how unserious this can get. Given the unimaginable cost of this mission, they are faffing around as your typical aunt with Windows Home laptops and iPhones? Seriously?

> faffing around

Sheesh, let the lab mice have a breather. Want them to solve physics during the trip?

Re: Artemis II crew take “spectacular” image of Earth

#355
post #286
post #245

Earlier quoted context omitted.

I think the clocks on board Orion are set to Houston time, which would be 5 hours behind UTC (because of Daylight Saving). But I'm not sure. I would expect the EXIF time to be in whatever time zone the spacecraft's clocks are set to. > clocks tick slower under the moon's weaker gravity. (Or is it faster?) Compared to clocks at rest on Earth, clocks on board Orion right now are ticking faster, because it's at a high e…

> So clocks on the ISS, for example, tick slower than Earth clocks; but clocks on the GPS satellites (orbiting at 4.2 Earth radii) tick faster (and there is an adjustment made for this on each satellite so that the time signals they send out match Earth clock rates) I'm curious, and hope you or somebody else might be able to answer this: is it a single adjustment for each thing, where they just set it to always adjus…

The exact difference in clock rates is not constant, because the orbits are not perfectly circular and the Earth is not a perfect sphere. So both the altitude and speed of the satellite, and the Earth's gravitational potential, are varying with time, and that means the clock adjustments will vary with time as well.

For the GPS satellites, their time signals are constantly compared with ground clocks, and adjustment signals are sent up to the satellites as needed to keep their clock corrections in sync with ground clocks.

I'm not sure what, if any, adjustments are made to clocks on the ISS, or how they're done.

Re: Artemis II crew take “spectacular” image of Earth

#356
post #213

Earlier quoted context omitted.

> It is the first time since 1972 that humans have travelled outside of the Earth's orbit. They mean outside of low Earth orbit (which basically means further away than the ISS). The phrasing is not ideal. > Earth's gravitational dominance extends 4x the distance to the moon "Earth's gravitational dominance" is not a single thing; it depends on what kind of "dominance" you're talking about. For example, even though t…

This video explains what you’re talking about re the moons orbit always curving toward the sun, and also mentions Earths gravitational dominance. It’s about the suns gravitational pull on the moon dominating over the Earths gravitational pull on the moon, but that due to the centrifugal force (there isn’t one, so conservation of angular momentum) the Earth's gravitational pull dominates. https://youtu.be/KBcxuM-qXec

The statement I made about acceleration due to gravity was with reference to an inertial frame centered on the Sun, in which there is no centrifugal force. The video you reference takes that viewpoint during its first part.

The claim about centrifugal force refers to the Hill sphere, which is a different notion of "gravitational dominance". The basic idea behind that is that, while the Sun's force on the Moon is greater than the Earth's, it varies in space, in the region where the Earth and Moon are orbiting, much less than the Earth's does. So we can "subtract out" the Sun's gravitational force, so to speak, since we can approximate it as constant in the region we're interested in.

The video, however, bungles this somewhat, because its claim about "centrifugal force" is made in a frame which is centered on the Sun--but rotating at the same rate the Earth revolves around the Sun. But nobody actually uses such a frame! Doing that would be silly. The natural frame for us on Earth to use if we "subtract out" the Sun's gravitational force to analyze the Earth-Moon motion is a frame centered on the Earth.

In this frame, we can say that the Moon orbits the Earth, not because there is some "centrifugal force" canceling out the Sun's force, but because we've subtracted out the Sun's force by centering our frame on the Earth. Or, to put it another way, we're treating the whole Earth-Moon system as freely falling in the Sun's gravitational field, and as long as the Sun's field is, to a good enough approximation, constant in the region we're interested in, we can simply ignore the Sun's gravitational force. (This viewpoint is much more natural in General Relativity, where "gravity" is not a force at all to begin with.) Such a frame is called an "Earth-Centered Inertial" frame, and it's the frame that's being used, for example, to manage the Artemis II spaceflight.

Re: Artemis II crew take “spectacular” image of Earth

#357
post #265

Earlier quoted context omitted.

I'm pretty sure people claim to be flat-earthers as a lark.

I know some MAGAs. I promise you they believe it 100%. They often talk of ice walls and one asked me if the Artemis mission would "break through the firmament"? There is a huge side of TikTok and Reels that most of us here would never find on our feeds which is dedicated to insane conspiracy theories and constitutes a large amount of the media that MAGAs etc consume.

If you think MAGA followers believe in flat-earth, you've deluded yourself badly.

Re: Artemis II crew take “spectacular” image of Earth

#359

Dear some very-rich person, please send a selfie-camera to the space! Yes, all that effort so we can keep looking at ourselves on a planet scale.

Good news! We already have that! If you pay taxes to the US that's one of the thing you've helped pay for:

https://www.nesdis.noaa.gov/imagery/satellite-maps

For reasons that are unexplainable if you're the NYTimes, polluting industries have been trying to kill these missions for decades.

Re: Artemis II crew take “spectacular” image of Earth

#360
post #356

Earlier quoted context omitted.

This video explains what you’re talking about re the moons orbit always curving toward the sun, and also mentions Earths gravitational dominance. It’s about the suns gravitational pull on the moon dominating over the Earths gravitational pull on the moon, but that due to the centrifugal force (there isn’t one, so conservation of angular momentum) the Earth's gravitational pull dominates. https://youtu.be/KBcxuM-qXec

The statement I made about acceleration due to gravity was with reference to an inertial frame centered on the Sun, in which there is no centrifugal force. The video you reference takes that viewpoint during its first part. The claim about centrifugal force refers to the Hill sphere, which is a different notion of "gravitational dominance". The basic idea behind that is that, while the Sun's force on the Moon is grea…

Sounds like you might have explained it better than the video.
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