The Space Thread

I'm not contesting that a business model based on aggressive innovation carries risks. What I am saying is that we are seeing more and more that the safe, careful model carries its own unique risks that seem to be underappreciated. With Boeing, the company seems to have fallen victim to its own regulatory capture. It's gotten so cozy with regulators and the stock market (never mind Congress) that, more and more, it values its public image above and beyond its commitment to safety and quality, particularly when it comes to software.

This comes from the top down, unquestionably, and so far seems not to be contagious, as ULA (a joint venture of Boeing and Lockheed Martin) is continuing to deliver impeccably reliable results despite its heritage.

What it comes down to is that I no longer have confidence that Boeing can deliver safe products. Boeing justifies its premium price and cost-plus contracting model with the assertion that it has an undeniable lead in experience and a proven history of quality. If that latter is no longer true, where does that leave us?

Edited by Fighteer on Feb 13th 2020 at 9:28:54 AM

Well, the point is that the concern is about Space X, not about Boeing. Just because Boeing can't be trusted with safety doesn't mean that the concerns about Space X are irrelevant.

Continuing on my planet theme, I wonder what people's thoughts are on this publication, which states that on average there might be 1 Earth-sized planet every 2 M-class stars (i.e red dwarfs) on average ("on average", because one star can have more than one such planet). And that - depending on how broadly you define "Earth-sized" - 0.15 - 0.41 planets per red dwarf might be within the habitable zone.

Well, it has been hypothesized that red dwarfs could be the last places in the universe where life can sustain itself on solar energy, so it's promising that there are so many potential planets out there.

Also, my point above is that maybe the concern should be about Boeing, or at least that each company should be scrutinized on its own merits. After all, SpaceX has almost sixty consecutive successful missions under its belt, a pretty good track record, and the Falcon 9 is set to beat ULA's Atlas V this year in the all time U.S. launch record (except for the Space Shuttle, of course).

Edited by Fighteer on Feb 14th 2020 at 8:47:11 AM

That said, the Atlas V also has a perfect safety record, so that doesn't tell much in itself.

Right, and it is an amazing launch vehicle. I am taking nothing away from ULA here. It has earned more and more respect in my eyes since I started seriously following rocketry. The CEO, Tory Bruno, is almost as much of a Twitter personality as Elon Musk is, and he's extremely transparent in discussing the company. If only more CEOs would display so much engagement with the public.

That said, Atlas V is more expensive than Falcon 9 for less lift capability, and it's not reusable. It's a respectable, reliable workhorse that is being out-competed. The upcoming Vulcan Centaur rocket is supposed to have some reusability features and is debuting in 2021, which is great and all, but if Starship works out, ULA will be like a guy in the 1950s who's incredibly proud to show you this new "horseless carriage" idea he came up with.

Edited by Fighteer on Feb 14th 2020 at 10:35:45 AM

Launch activity updates:

• Northrop Grumman: Antares 230+ | Cygnus CRS NG-13 (S.S. Robert Henry Lawrence Jr.): February 15 20:21 UTC (3:21 PM EST). NASA livestream will start approx. 1 hour before launch.
• SpaceX: Falcon 9 Block 5 | Starlink 4: February 16 15:25 UTC (10:25 AM EST). The static fire was green, but the launch has been moved to Sunday due to weather conditions in the recovery zone.

Edit: Way to put the lie to my post. NG-13 was scrubbed for today due to upper-level winds [1]. The new date has been edited in.

Edited again for another bit of news:

• Blue Origin is opening its rocket engine production facility in Huntsville, AL. [2]. This will produce the BE-4 open cycle methane/liquid oxygen engine, intended for use on ULA's upcoming Vulcan Centaur rocket and Blue Origin's upcoming New Glenn, both of which could see their first flights in 2021. The engine is designed to be reusable, and both of those vehicles will be partially recoverable.
  • Vulcan Centaur will separate its engines and thrust structure after launch, which will fall to Earth and deploy parachutes for what I believe is an air catch.
  • New Glenn's first stage booster will return to Earth and land propulsively on an autonomous drone ship, just like SpaceX's Falcon 9.

And more... Stop it, Twitter!

• SpaceX's latest Crew Dragon spacecraft has arrived in Florida and will begin flight preparations [3]. This is the one that will take astronauts Doug Hurley and Bob Benken to the International Space Station for the first manned flight from U.S. soil in 10 years.

Edited by Fighteer on Feb 14th 2020 at 2:54:42 PM

Space news keeps happening.

From this Twitter post [1], NASA has awarded a fixed-price contract to Rocket Lab to send a cubesat to the Moon as part of its Launch Services Program. This mission, targeted for early 2021, will take advantage of the company's new Photon kick stage, which is designed to allow incredible flexibility of orbital delivery to customers.

That's great news for Rocket Lab and for commercial launch services in general.

The standing theory is that Uranus is tilted because of a planetary collision, right? I'm wondering if there are other plausible theories

Unless I'm mistaken axial tilt requires a collision or very near colision.

You can have distant interactions alter orbits but altering a bodies rotational axis needs either physical contact or a close enough approach to have significant gravitational shear between poles; even then I'm not sure you'd get enough torque from gravity before the interacting bodies are in contact anyway.

• Northrop Grumman: Antares 230+ | Cygnus CRS NG-13 (S.S. Robert Henry Lawrence Jr.): The launch was successful and on-time. It was the usual CGI show after staging, but made a lot more amusing than usual due to an open mic on the comm net, followed by someone making a failed phone call, then the display itself going completely bonkers before cutting to a view of the pad. Oh, well, at least Cygnus got up.

• SpaceX: Falcon 9 Block 5 | Starlink 4: Tomorrow's launch was scrubbed due to a valve issue on the second stage. New target Monday, Feb 17.

That sounds right but I don't recall any specific details.

Edited by Fighteer on Feb 15th 2020 at 6:02:06 AM

I've seen models that investigate the possibility of gravitational interactions with just existing bodies in the solar system, hypothetical bodies that have either been destroyed by collision or ejected and various combinations there of but most of those have been focused on Venus and its even more extreme tilt (Venus at some point on the past was actually flipped so that it now rotates retrograde. Given the net angular momentum of the Solar System this is not something that just happened).

I've seen less modelling for the outer solar system, though I have also seen models where Uranus and Neptune actually swapped positions early in the Solar Systems life so there's the chance for some rather complicated gravitational interactions causing the Uranus's extreme axial tilt.

One of the weirder bits of Solar System history to me is Jupiter taking a trip to the inner regions till Saturn managed to pull him back.

That sounds weird given that Jupiter has twice the mass of Saturn.

Not really given the presence of so many Hot Jupiters in our exo-planet lists. No some of this is detection bias, Hot Jupiters are easier to find than most exo-planets but they do exist and they seem to be fairly common so there's also go to be a question of why that didn't happen when you find a Jovian-class gas giant that didn't do that and in our solar system Saturn is the most likely answer.

And even smaller bodies can have noticeable effects on larger ones. Look at what our moon is doing on Earth's rotation (namely slowing it down).

Meanwhile in a follow-up to Betegeuse being unusually dim... it gets weirder. Turns out that part of this abnormally large degree of dimming is confined to one part of the star. Possibly something like the mother of all sunspots or a coronal mass ejection shading part of the surface when viewed from Earth (or some combination thereof. These possibilities and others are not mutually exclusive. In fact multiple causes working in tandem may explain the severity of the dimming event).

I get that we use spectrometry to detect gas giants orbiting distant stars, but is there a reason we can't do the same for rocky planets as well?

I mean, aside from the observation of a star's wobble that indicates there's a planet rotating around it.

Scientists already do this. The planet detection technology has advanced enough that we can spot Earth-sized planets - such as Proxima Centauri b. That's how we know that on average 20% of all Sun-like stars have an Earth-sized planet in the habitable zone, for example.

Exomoons are a little harder, though.

Exoplanets (and exomoons) are detected in two primary ways: their effects on the motion of their parent bodies, and their effects on the light emitted by those bodies.

To detect motion, you observe either the parallax of the star (if close enough) or its spectral shift due to relative velocity. If you know its mass and distance, you can tell how much its velocity is being modified by whatever is orbiting it, and thus the mass and orbital period of that body (or bodies). Of course, since planets are such a tiny fraction of the mass of their parent star, this effect is tiny and can be extremely difficult to measure.

To detect occlusion, on the other hand, you look for the emission spectra of the parent stars to find dips in brightness, or even changes in the spectral lines, indicating that a body is passing in front of it. For this to work, however, the orbital planes of those secondary bodies must be parallel to us: we have to see the system edge-on, and that only occurs in a very small number of systems. Further, the body must be large enough for the change in brightness to be detectable. Lastly, its period needs to be relatively short, because we can only train our telescopes on the same star for so long before having to move on.

As we get better and better instruments, the thresholds for detection of these phenomena go down, and thus we detect more and more exoplanets (and moons).

Edited by Fighteer on Feb 16th 2020 at 10:22:27 AM

Some of those moons are mega-Earth-sized as it is.

Brown dwarfs and super-Jupiter's don't always go in for petite partners.

If memory serves (but I can't find a reference) planet size scales to some degree with star size. Granted I don't remember if this is a physical thing or an observation bias.

It would almost certainly be observation bias, since a larger star would need a larger orbiting body to perturb or occlude it enough to be detected.

Yeah, trying to remember which Gliese ## or ### has what gets hard after a while.

We need to start rethinking the naming system.

But, my take-home from watching the various observations roll in has been "planetary and satellite formation may follow a simple enough set of premises, but that doesn't stop it getting really effing diverse".

Edited by Euodiachloris on Feb 16th 2020 at 3:59:20 PM

I guess it's also difficult to measure outer solar system bodies that have orbital period of decades, like an exo-Neptune or such.

Maybe they should have a list of names for all potential planets discovered. Would sure make it easier than some seemingly random serial number.

Rules are parent star's name followed by a lower case b, c, d etc in order of discovery (not order out from the star... though if multiples are confirmed from the same observational data it will proceed outward from the star). For multiple star systems it's star name A (or B or C etc) in upper case, followed by the lower case letter for the planet. (Technically Proxima Centauri b is Alpha Centauri C b). If the planet orbits two stars for close binaries it would Star Name AB b and so on.

We dinged 1k exo-planets known several years ago and the number has only grown since. We don't have enough names for all the known stars, if we star adding planets its going to get ridiculous.

Science fiction actually has some great suggestions here. If we start colonizing these worlds, the colonists get to name them. Aside from that though, it hardly seems worthwhile going to the trouble of getting emotionally invested in a world that nobody will ever see or live on.

Unless they call another scrub, SpaceX's Starlink mission will lift off at 10:05 AM EST (15:05 UTC) today (SpaceX Livestream). This mission will have a slightly different profile than previous ones. Rather than coast for ~45 minutes before performing a circularization burn, followed by deployment at T+1 hour, there will only be one second stage firing, and the satellites will be deployed at approximately T+15 minutes. We'll also see if they get the double fairing catch they've been hoping for.

Edited by Fighteer on Feb 17th 2020 at 8:17:38 AM