> four suitcase-sized satellites Americans will use anything else but the metric system :)
[deleted]
NASA to launch space observatory that will map 450M galaxies
71–80 of 134 posts
Re: NASA to launch space observatory that will map 450M galaxies
#72[flagged]
Could you please stop taking HN threads on generic flamewar tangents? You've been doing it repeatedly, unfortunately. It's not what this site is for, and destroys what it is for.
Re: NASA to launch space observatory that will map 450M galaxies
#73Earlier quoted context omitted.
Dragon lacks a Remote Manipulator System (Robot Arm) and a airlock. things that make servicing objects in space a lot easier. Im sure somewhere at NASA or SpaceX there is rough set of specs on what a shuttle like starship would look like complete with payload bay, robot arm, and eva airlock.
The complete specs of the arm may now belong to a hostile nation.
It's amazing how all it takes is a few threats of annexation, and for GOP thought-leaders like Ben Shapiro to start talking about enslaving you[1] to work on the Panama Canal to make another country rethink its relationship with you.
Absolute animals. As is anyone else carrying water for these politics. There's no excuse for it.
If you had anything at all to do with putting these clowns in power - reign them back in. They are supposed to work for you. Remind them of this.
[1] https://x.com/benshapiro/status/1876800394900152483?lang=en
Re: NASA to launch space observatory that will map 450M galaxies
#74Earlier quoted context omitted.
They're talking about galaxy evolution in the early universe, over timescales of millions of years. Statistics measured across the (large) sample group, not within one galaxy. Scroll down to "It will classify galaxies according to redshift accuracy..."
Right, at that scale, For a galaxy to move a fraction of a centimeter will take a thousand years. So not much will be missed in a gap of 6 months.
This is nonsensical. Do you mean a tiny movement in the field of view, which should be measured in angular distance?
Or do you mean actual motion through the universe, in which case the galaxies are moving at hundreds of kms per second, which means they would move billions of kms in 6 mos.
Re: NASA to launch space observatory that will map 450M galaxies
#75Earlier quoted context omitted.
The complete specs of the arm may now belong to a hostile nation.
If you're alluding to Russia, they've had them. They even failed in making their version of a shuttle. With what money would they do anything with now? If you're alluding to China, they probably had the data from the Russians anyways. Otherwise, I'm out of guesses to your vagueness.
Canada built the shuttle arms: https://en.m.wikipedia.org/wiki/Canadarm
Re: NASA to launch space observatory that will map 450M galaxies
#76Earlier quoted context omitted.
The complete specs of the arm may now belong to a hostile nation.
If you're alluding to Russia, they've had them. They even failed in making their version of a shuttle. With what money would they do anything with now? If you're alluding to China, they probably had the data from the Russians anyways. Otherwise, I'm out of guesses to your vagueness.
> They even failed in making their version of a shuttle.
Nitpick: It was sort of successful. They built a shuttle, and it successfully flew a single (un-crewed) mission of a couple orbits. The collapse of the USSR / lack of funding killed it.
Re: NASA to launch space observatory that will map 450M galaxies
#77Earlier quoted context omitted.
To answer three of your questions: - It is passively cooled rather than using an expendable coolant- "SPHEREx relies on an entirely passive cooling system — no electricity or coolants are used, simplifying the spacecraft’s design and operational needs." - It is a Medium-Class Explorers (MIDEX) mission - Investigations characterized by definition, development, mission operations, and data analysis costs not to exceed…
ah, I misread the Orbital Parameters on the wiki. that day-night orbit is also a LEO which makes it even more possible to do a manned mission for upgrades. Oh, wait, we no longer have a shuttle for those types of missions.
Remember, it is passively cooled (a major design plus and, I assume, part of why it was able to achieve the cost it did). So there would be no need for a manned mission. And in fact, at that cost, it wouldn’t make sense anyway.
Re: NASA to launch space observatory that will map 450M galaxies
#78Earlier quoted context omitted.
To answer three of your questions: - It is passively cooled rather than using an expendable coolant- "SPHEREx relies on an entirely passive cooling system — no electricity or coolants are used, simplifying the spacecraft’s design and operational needs." - It is a Medium-Class Explorers (MIDEX) mission - Investigations characterized by definition, development, mission operations, and data analysis costs not to exceed…
Possibly stupid question: how does this polar orbit stay over the terminator? And how is the terminator defined for a polar orbit here, since both the north and south poles are on the terminator only at the equinoxes?
>how does this polar orbit stay over the terminator?
Because it's launched at a angle greater than a straight north-south 90 degree orbit, so orbital precession will correctly follow the terminator. Depending on the orbital altitude this can be more than 140 degrees: https://en.wikipedia.org/wiki/Sun-synchronous_orbit
Re: NASA to launch space observatory that will map 450M galaxies
#79"The SPHEREx mission will map the entire sky four times over two years, offering scientists a chance to study how galaxies form and evolve, and providing a window into how the universe came to be." So each object will be scanned ~6 months from the previous scan. How much evolving within the universe will be noticeable within that 2 year run? My gut response is not much, but that's why we do the science to see the cha…
A nearby (excellent) comment (https://news.ycombinator.com/item?id=43338459) gives further context, but: the 6-month revisit period is just an artifact of the Earth-orbit-based sky scanning strategy. In 6 months the satellite, precessing at 1 degree/day, and facing away from the sun during data collection, will scan the sky completely. (See Fig 1 of the paper [0]).
So in particular, the 6-month period is not to revisit these distant galaxies more than once to observe spectral changes. The strategy, indeed, is to “stack” the multiple exposures to beat down noise. (Fig.6 of [0], top left).
It is possible that they have designed the system so that it could produce “just good enough” results in 6 months, with one complete scan. This is called a “threshold mission” and it would only be described in the full proposal.
I looked through the rest of the science cases (which are secondary to the driving case of this mission), and none of them seem to be reliant on revisits. (But open to correction on this.)