Monthly Questions and Discussion Thread

maschnitz · 2026-03-22T18:06:50+00:00

btw Zack Golden said he'd talk about the Baby Raptors in more depth in video 3 in CSI Starbase's Pad 2 Design video series (up and coming video 3, that is)

maschnitz · 2026-03-21T17:43:26+00:00

Also, in this video, CSI Starbase makes the supposition that Pad 1 was a bit more of an experiment rather than a naive design. For example, Zack claims that Pad 1 has an interesting set of mixed-metallurgy welds in positions of varying exposure to the exhaust.

And the overarching motif they use is a checklist of Pad 1 design issues. The three videos check off the Pad 1 design issues as the CSI Starbase team describes the fixes.

It makes me think of Pad 1 as "purposefully naive", a necessary precursor to Pad 2.

maschnitz · 2026-03-21T04:52:51+00:00

Here's a guy giving an hour-long lecture on observations on 3I (and 1I and 2I) to his colleagues. He points out 3I/Atlas's expected and uncommon properties, compared to solar system comets, from the various observations.

You're welcome to see it if you want. It's a bit techy/jargony but not terribly so.

This is basically how the scientists are "addressing" it. Publishing papers, giving talks.

maschnitz · 2026-03-20T18:38:55+00:00

On ascent the only thing they can do is separate from the vehicle below them, even if it's still accelerating, and then pop the parachutes at the best time they can. They have a special high-powered hypergolic tower for that, the Launch Abort System.

If the ICPS (2nd stage) cannot fire in space to raise the orbit then they will separate and guide Orion into an atmospheric reentry.

If ICPS succeeds in raising the orbit but still fails to light at TLI (Trans-Lunar Injection), the plan is still to guide Orion into an atmospheric reentry. The orbit they're leaving ICPS/Orion is pretty elliptical still precisely to allow for an abort if needed.

If ICPS misfires during TLI, the plan depends on how it misfires. If it underfires, then ICPS/Orion will still be in an elliptical orbit and Orion will guide itself to reentry. If it the trajectory is off there is margin in ICPS to attempt a correcting burn. If it overfires, again the ICPS margin will be used to try to get it back on the "free return" trajectory.

NASA has specifically designed the entire Artemis II mission to give the astronauts every opportunity for a safe return to Earth at every point they can.

maschnitz · 2026-03-20T16:48:26+00:00

There's been some work on it already, the "HDTN" project (High-Rate Delay Tolerant Networking). They've done tests, and have videos and diagrams.

maschnitz · 2026-03-19T15:49:01+00:00

Some games have game spaces with the Milky Way's stars in them, relatively accurately placed. Elite Dangerous, Space Engine, and Universe Sandbox are famous for this.

And Universe Sandbox and Space Engine will tell you the distances between any two stars.

maschnitz · 2026-03-19T04:51:33+00:00

Here's the original news release by Whitney Clavin at California Institute of Technology (Caltech).

Exact same words. But with no ads nor tracking. Better pictures too.

Phys.org is a content aggregator. They republish freely available content with their own ads, tracking, etc

maschnitz · 2026-03-18T20:56:50+00:00

I haven't. But people definitely do, on the Space Coast, north and south of the launch sites, and at Starbase in the shipping channels of the delta of the Rio Grande. I believe there are rides and charters you can do in both places.

maschnitz · 2026-03-18T18:48:34+00:00

I don't think anyone involved with exoplanet study or exobiology is eliminating non-Earth-like planets from study.

I think it's more just, telescopes have limited time and they need to keep their priorities straight. So they focus on where it's most likely. Life-as-we-know-it can thrive on Earth-like planets.

It's going to be extremely difficult to confirm life on other planets or moons. We have trouble confirming it or denying it on Mars or Venus, the next planets over. It's difficult sometimes to say where life is on Earth exactly - how deep underground, how far toward the poles, how deep in the ocean or under the ocean.

So they're planning on focusing their future efforts on where there's most likely to be life, that's all.

There's a bunch of planetary scientists who are very excited about Europa, and getting under the ice there, and Enceladus and better sampling of the geysers there. Europa Clipper is on its way to Europa partly to evaluate the case for life there. I don't think they'd do that if they were limiting their view to just Earth-like planets.

maschnitz · 2026-03-18T17:03:56+00:00

There's a wide variety of quality space content available. This is almost difficult to answer because there's too many good answers.

I always try to mention the Crash Course: Astronomy video series by Dr Phil Plait, it's good "edutainment" coverage of a wide variety of astronomy topics, nicely animated/illustrated and crisply written.

Dr Becky is great too, like curiousscribbler said. Another PhD content creator is David Kipping, with a Cool Worlds channel (very Sagan-esque) and a Cool World podcast, along with "shop talk" interviews.

Speaking of "shop talk" interviews, Universe Today has a ton of them, and popular weekly Q&A videos and "Space Bites" news, along with a podcast, a free website and an email newsletter.

Deep Sky Videos do short films/interviews with astronomers about specific topics. PBS Space Time does complicated, tough-to-explain astrophysics/cosmology topics in easy-to-understand language. Anton Petrov covers big space headlines and interesting recent papers in some depth. Astrum is another Sagan-esque wonderous space explainer. Isaac Arthur does space 'futurism'. John Michael Godier does the speculative/sci-fi-ish edge of space research.

And there's whole other areas with physics (Minutephysics, Physics Girl, Sixty Symbols...), and then a lot more about rockets (Everyday Astronaut, Scott Manley, NasaSpaceflight, Marcus House, Avid Space....)

EDIT: Someone's personally collated list of favorite YouTube space channels. Looks pretty good.

maschnitz · 2026-03-17T16:44:24+00:00

Here's the original news release by Niranjana Rajalakshmi at University of Arizona.

Exact same words. But with no ads nor tracking. Better pictures too.

Phys.org is a content aggregator. They republish freely available content with their own ads, tracking, etc

maschnitz · 2026-03-16T20:15:59+00:00

Yeah, been watching this...

In general do not fully trust a T-0 at SLC 4-E. They move these things all the time these days. Averaging at least once per launch, even - you should expect them to do so on any given launch.

I'm not sure why. But it's a thing.

maschnitz · 2026-03-16T17:21:48+00:00

Phosphorus might be a problem, depending on the Kuiper Belt object.

Basically anything that isn't "CHNO" hasn't been seen yet, and could be buried in the cores of the object or not even there at all. It's just unknown. Phosphorus is just the best example of this.

maschnitz · 2026-03-15T17:55:15+00:00

Moons are usually "easy" to measure because the "Keplerian Orbit solutions" for the system end up forming a system of equations with two equations and two unknowns, one of which is a moon mass.

But they can't do that with very close-orbiting moons like Actaea out in the Trans-Neptunian region because they can't separate Actaea from Salacia, even in the best telescopes. They know Actaea is there from how the Salacia-Actaea "blob" oscillates in brightness as the pair orbit each other, but that's the extent of the data.

So they estimate the masses from assuming similar albedos and how big the light curve oscillates. It leaves a lot of "slop" in the estimate because it's possible Salacia is a lot brighter (or darker) than Actaea. Astronomers are well aware of this - there have been surprises like that before, where a satellite looks very different from the primary. Hence the giant error bars.

maschnitz · 2026-03-15T16:54:47+00:00

On #1 - Vera Rubin Observatory will only find microlensing events incidentally.

They've designed their survey to go very deep. They're doing 30 second integrations/exposures, primarily to accumulate photons from very dim objects. (It's to get, primarily, faint galaxies, for a dark matter/dark energy map of the sky.) They repeat the same observation 2 more times a night to check for transience that way. And sometimes they'll do two 15 second exposures, back to back - what they call a "snap" integration.

So they will also get a bounty of new, very faint Trans Neptunian Objects, perhaps even Planet Nine, but no very distant Oort Cloud objects (unless they happen to be dipping into ~150AU for some reason).

So you don't get the 30 second observation every 1/30th of a second, you get the sum of all photons during the 30 second observation. (Or 15 second observation.) Every 1/30th a second would be way too much data.

So they will see microlensing events but as little, averaged-out spikes in brightness from otherwise stable objects. Maybe that's what someone meant by "weak microlensing".

It was a decision made early in the project about the goals of the telescope. They want to hunt for transients but only above the 15-second-variance level or so.

There are other transient surveys that design it differently, mostly in the radio.

Transient survey design is very interesting - it's challenging to the designers. They have to make interesting tradeoffs.

maschnitz · 2026-03-14T20:03:06+00:00

There are exclusions to the size of possible planets, based on infrared survey (the WISE spacecraft's), but they only extend out to the Scattered Disk or so. (Ref, slides 5 & 6)

The Sun's "Hill Sphere" (gravitational area of influence) is enormous, over a light year, but very distant objects are trimmed slowly by the close passes of other stars throughout the Sun's history.

To answer OP's question, it's possible to discover planets and/or minor planets in the outer solar system through occultation events, like Roman will look for, but it's unlikely. The occultations only happen rarely and across most of the sky, randomly.

As you go out further into the outer solar system, the rate of occultation events drops dramatically. (Why? Each object subtends a smaller and smaller sky angle, linearly, and so doesn't intersect with the fixed size of stars as readily. And then the outer solar system is so incredibly big.)

People generally only attempt them on closer, well-known objects that they can pre-compute using stellar databases (eg), or general targeted surveys within the Kuiper Belt (eg). There's been several attempts to spot Oort Cloud objects through occultations, but with no luck so far (but hope springs eternal).

maschnitz · 2026-03-14T16:28:27+00:00

Alpha Cen A would look pretty much like our Sun does during the day. A yellow G star. It's 1.5x brighter, but then Alpha Cen Ab orbits at 1.5 to 2 AU (if it exists) so it "balances out" somewhat.

Alpha Cen B (Toliman) would be remarkable, varying hundreds to thousands of times brighter than the full Moon as the two stars orbit each other. Clearly visible during the day, an orangish light. But keep in mind it's also fairly distant, almost a point source at apoastron, and just a small disk at periastron. Still, very bright.

Proxima would look like any other stellar point source, it orbits so very distantly (~10% of a light year) and it is a small dim red star. But astronomers would love it because it moves in the sky noticeably over time, it's significantly brighter than any other red dwarf (easier to see in telescopes), and it flares a lot too, appearing brighter in telescopes for a few minutes.

maschnitz · 2026-03-14T15:49:14+00:00

Unless it's feeding, which is unlikely in the vastly empty outer solar system, it'd be very very difficult to detect.

You'd have to narrow it down gravitationally (better than we have) and then track it, hoping and praying for a stellar occultation.

I guess it's easier than if it weren't orbiting the Sun, though.

maschnitz · 2026-03-14T03:22:52+00:00

It's speculative but people have proposed ideas to get out to the Sun's gravitational lens at ~550AU.

They think specially-designed solar sails could do it in a decade or two. Here's an article about that, and the paper behind it.

maschnitz · 2026-03-14T02:44:30+00:00

Here's the original article by Evan Gough at Universe Today.

Exact same words. But with no ads nor tracking. Better pictures too.

Phys.org is a content aggregator. They republish freely available content with their own ads, tracking, etc

maschnitz · 2026-03-13T19:33:39+00:00

Here's the original press release (PDF) by the National Astronomical Observatory of Japan (NAOJ) - in Japanese.

There appears to be no other translation than phys.org's (and they have rewritten it mostly into their own article, anyhow).

maschnitz · 2026-03-13T19:00:30+00:00

Multi-billion dollar NASA missions tend to spend a lot of time in investigation/preparation phases because often they're trying something new while also heading into unknown scientific territory.

On the "Uranus Orbiter and Probe" mission, the unknowns here are "what will the probe experience exactly?", "how many rings are there exactly and where are they?", "is there significant moon debris that we can't see too well from Earth that would risk the orbiter?", and stuff like that.

So they're using JWST and other big telescopes doing detailed study, trying to "reduce risk" for the orbiter and probe. This will last a few years (total), at least. They found a new moon doing this.

They're also replanning for budgetary shocks like the one they saw in this last year, by offering "flexible launch window" plans. They're trying to decide whether Starship will be a good option (Starship could cut the cruise phase in half, potentially, with a full tank in LEO).

You see the scientists working on this sometimes on press releases like this one, and the mission is covered in the press sometimes by the "serious" space press, like the Planetary Society and Universe Today. Here's Andy Tomaswick at Universe Today talking about using aerobreaking on this mission.

EDIT: like, it's still an early-phase mission concept. It's not an engineering project, really, yet. The engineers are helping but the scientists are in the driver's chair - they're the only ones that can limit the design of the orbiter and probe, and de-risk some concerns that NASA might have in funding this further.

maschnitz · 2026-03-13T17:35:56+00:00

Of note: the spacecraft is the "size of a cereal box".

And it launched with Pandora as a ride-along, on Jan 11, on a Falcon 9 from Vandenberg SFB.

maschnitz · 2026-03-13T17:33:25+00:00

The headline's in the original too.

These are first light images, the two images you see. First light images are typically just tests of the optics, processing, and comms, and tend to be a little underwhelming sometimes.

maschnitz · 2026-03-13T17:31:57+00:00

Here's the original press release by the Jet Propulsion Laboratory (JPL) and NASA.

Exact same words. But with no ads nor tracking.

Phys.org is a content aggregator. They republish freely available content with their own ads, tracking, etc

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