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Comment by niwtsol | Hacker News Reader

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 $180 to $200 million total cost to NASA. I think the cost of ground support eats into the budget length. The original estimate for project was $241M, so it was a large MIDEX

- It is in a Polar orbit around Earth at the day-night (terminator) line

https://www.jpl.nasa.gov/press-kits/spherex/

https://explorers.gsfc.nasa.gov/missions.html

https://spaceflightnow.com/2019/02/14/nasa-selects-mission-t...

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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

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.

Even a Dragon could bring enough hardware and a crew for a small upgrade or repair (to say nothing of the upcoming Starship).

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.

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

> 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.

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

Sorry, "rein them in". Reign is about royal power; rein is about controlling a horse. And we definitely don't want any monarchs here.

A nation pushing back against the morons in Washington.

Hardly hostile. Unless you poke the bear.

I think it would be more rightfully described as poking the beaver

Touché!

https://en.m.wikipedia.org/wiki/Canadarm#

Can dragon launch to a polar orbit and safely deorbit from a polar orbit?

https://en.wikipedia.org/wiki/Fram2

There was also Polaris Dawn about 6 months ago. They did a highly polar orbit

I don't want to quibble just to be contrarian. Polaris Dawn was at the International Space Station's inclination, 52°, which is the most common destination for human astronauts. Isn't usually considered a polar orbit.

I want rather to clarify a really neat point, about what the other mission's doing. From KSC, you can conventionally only launch to inclinations below 62° [0] (constrained by populated landmasses). To get to a true polar orbit from Florida, that means they have to attempt a curved launch [1]—something that's pretty rare, and (to my knowledge) Falcon itself never tried before. (The parent comment was right to ask whether a polar orbit is possible: it does create interesting challenges).

[0] https://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Co...

[1] https://en.wikipedia.org/wiki/Dogleg_maneuver

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