Recent comments in /f/space

Rhaedas t1_j6k1trx wrote

Reply to comment by hagfish in ‘Extraordinary’ footage shows one of the closest known approaches of a near-Earth object — On 26 Jan. 2023, asteroid 2023 BU was about 2,200 miles above the surface of the Earth by marketrent

Tunguska or the more recent Chelyabinsk meteor were larger objects. Estimates of Tunguska are around a 50 meter icy body and the more recent one was around 20 meters. An 8 meter body means a lot less mass and effect.

Tunguska was a lot more impactful because of its probable angle of impact based on the patterns of the explosion, getting it lower before it detonated from the pressures. Chelyabinsk would have been a lot worse had it also been that straight of an angle in, but less total area affected for the same reason.

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Shrike99 t1_j6k1i1e wrote

Reply to comment by laxkid7 in NASA tested new propulsion tech that could unlock new deep space travel possibilities by Creepy_Toe2680

By my count there have been 9 solar sail demonstration missions launched, the first being Cosmos 1 in 2005 and the most recent being the NEA Scout launched just a few months ago.

However, the vast majority of these missions have either outright failed or been a dubious success at best. The only one which has been truly successful and demonstrated practical use of a solar sail was IKAROS in 2010, which operated successfully until 2015.

It only takes one success to prove that the concept works, but the large number of failures seems to have tempered expectations and dampened enthusiasm somewhat.

There was a proposed follow-up to IKAROS called OKEANOS intended to go to the Trojan asteroids, which would have been the first real use of a solar sail for a scientific mission.

It was a finalist for ISAS's consideration in 2019, but ultimately lost to LiteBIRD. Unfortunately there just isn't enough space science funding for all the missions people would like to do, so a lot of neat stuff gets passed on.

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ye_olde_astronaut OP t1_j6jzlyh wrote

Reply to comment by Who_DaFuc_Asked in Habitable Planet Reality Check: TOI-700e Discovered by NASA’s TESS Mission by ye_olde_astronaut

> it's in the habitable zone of a red dwarf star (so it'll be tidally locked)

So? Taken directly from the linked article: "Increasingly detailed climate modeling over the last quarter century has shown that synchronous rotation is not the impediment to global habitability as it was once thought. In fact, it has been predicted that slow or synchronous rotation can actually result in an increase of the Seff corresponding to the inner edge of the HZ owing to feedback mechanisms which result in the formation of a reflective cloud layer on the perpetually daylit side of the planet."

> it is around the same diameter as the Earth, slightly more massive

No, according to the linked article the mass of TOI-700e is unknown. But, according to the linked article: "based on a statistical analysis by Chen & Kipping of the mass-radius relationship for exoplanets with known radii and masses, the estimated mass of TOI-700e is about 0.85 +0.67/-0.34 times that of the Earth"

So the most probable mass of TOI-700e is 0.85 times that of the Earth (not "slightly more massive" as you claim).

> it is pretty much on the very inner edge of the habitable zone

So? According to one of the references used in the linked article and by the discovery team of TOI-700e (R. K. Kopparapu et al. 2013), the inner edge of the habitable zone for the Sun is at about 0.97 AU. Earth, at a distance of 1.00 AU, is right at the inner edge of the habitable zone and is still habitable.

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Rhaedas t1_j6jzbo5 wrote

Reply to comment by Sylph_uscm in ‘Extraordinary’ footage shows one of the closest known approaches of a near-Earth object — On 26 Jan. 2023, asteroid 2023 BU was about 2,200 miles above the surface of the Earth by marketrent

Knowing what's out there is the first step. Perhaps if we knew there were a lot more and the odds were good one would hit soon, there'd be more push to fund doing whatever we could to intercept. Plus getting better ways to detect and project paths leads to a longer time knowing a better final target, so even if we couldn't do anything, having days instead of hours to move people from a city would be worth it.

It's how hurricane and other storms used to be vs. what we know now. We can't do much of anything about the smaller threats of tornadoes, but we still try to improve accuracy of time and location.

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wombat5003 t1_j6jzbml wrote

Reply to NASA tested new propulsion tech that could unlock new deep space travel possibilities by Creepy_Toe2680

This will be the future not of space exploration, but mining ore… this is the start of humans building out past the confines of our planet to making possibly a series of rings around Mother Earth using ore from asteroids as material.. think I’m crazy?? Maybe not… Ask Larry Niven :)))) Ringworld is coming!!

Seriously I say this because if ya think about it, it takes 18 months currently to get to the asteroid belt with what tech we have. With this new way, we could cut the round trip significantly which makes mining a viable prospect..

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Shrike99 t1_j6jxdxg wrote

Reply to comment by DownvoteEvangelist in NASA tested new propulsion tech that could unlock new deep space travel possibilities by Creepy_Toe2680

We've had plenty of solar powered electric propulsion since. The Dawn mission was a great example of what electric propulsion can do. Solar power just doesn't scale up well to larger vehicles, or work very well as you get furthur from the sun.

A nuclear electric system has the potential to be much faster than a chemical rocket over long distances, i.e to Mars or especially beyond.

The real issue has been the reluctance to put nuclear reactors into space. SNAP-10A remains the only example the US has ever launched, even though much better designs like the SAFE-400 and KRUSTY have since been developed.

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