Tau Ceti has planets after all!

[_Augustus_]

https://news.ucsc.edu/2017/08/tau-ceti-planets.html

Planets e and f might be barely in the habitable zone (similar to Venus and Mars distances respectively).

[Bill Phil]

It says nearest sun-like star, but I'm pretty sure that there's a yellow dwarf in the Alpha Centauri system... maybe they mean more than just physical characteristics...

I guess we can expect a visit from the Race. After all, they are from Tau Ceti...

[vger]

Dayum, those are massive. Fascinating how similar they all are in size.

Edited August 10, 2017 by vger

[Spaceception]

12 hours ago, Bill Phil said:

It says nearest sun-like star, but I'm pretty sure that there's a yellow dwarf in the Alpha Centauri system... maybe they mean more than just physical characteristics...

I guess we can expect a visit from the Race. After all, they are from Tau Ceti...

I think they meant closest individual Sunlike star.

 

But this is great, more planets, and more HZ planets within 20 ly, dang they seem pretty common actually. 

[_Augustus_]

1 hour ago, Spaceception said:

But this is great, more planets, and more HZ planets within 20 ly, dang they seem pretty common actually. 

But where are the aliens? If habitable planets are common, then extraterrestrials should be too.

[Rakaydos]

1 hour ago, _Augustus_ said:

But where are the aliens? If habitable planets are common, then extraterrestrials should be too.

If they're from a super earth, their rocket programs would be even more expensive than ours. They might never have gotten offworld at all. (or if they did, they did a flag and footprints on the nearest body and forget the whole thing)

[ProtoJeb21]

3 hours ago, _Augustus_ said:

But where are the aliens? If habitable planets are common, then extraterrestrials should be too.

I honestly doubt that any intelligent life exists on the outer two planets of Tau Ceti. While conditions could be suitable for simple life to evolve, frequent asteroid impacts and rather uncomfortable climates would keep any biology at a microscopic stage. Still, the Tau Ceti system is quite interesting and is the FIRST system with spread-out terrestrial planets around a Sun-like star found with the radial velocity method. I hope there are some gas giants further out in the system, because conditions for life could arise on a Europa-like moon.

[Kerbart]

5 minutes ago, ProtoJeb21 said:

I honestly doubt that any intelligent life exists on the outer two planets of Tau Ceti. 

But if it does, it's likely going to be the most vile and unpleasant species in the galaxy!

[Xemina]

Nyoh! I was just about to make a thread on this!

[_Augustus_]

8 minutes ago, ProtoJeb21 said:

because conditions for life could arise on a Europa-like moon.

We don't know if Europa has life yet, though.

[TheEpicSquared]

1 hour ago, Rakaydos said:

(or if they did, they did a flag and footprints on the nearest body and forget the whole thing)

Like us, in the 1970s-onwards?

[Rakaydos]

1 minute ago, TheEpicSquared said:

Like us, in the 1970s-onwards?

Except they needed something like a NOVA-class rocket just to get into orbit, and every mission takes orbital assenbily, geosynch is too far away to be economically useful, and they give up the whole thing as a bad deal.

[Spaceman17]

20 minutes ago, Rakaydos said:

Except they needed something like a NOVA-class rocket just to get into orbit, and every mission takes orbital assenbily, geosynch is too far away to be economically useful, and they give up the whole thing as a bad deal.

if they are in another solar system they have another type of propellants at their disposition, so they could be using a V2 to get to our solar system, or simply cannot get into space

[Spaceception]

1 hour ago, Rakaydos said:

Except they needed something like a NOVA-class rocket just to get into orbit, and every mission takes orbital assenbily, geosynch is too far away to be economically useful, and they give up the whole thing as a bad deal.

Hmm, I wonder what it would take to get into orbit, what's the smallest possible rocket that could reach orbit, and what would it's payload be?

I know there's a simple calculation to see the to get into orbit and escape the planet's gravity, but I can't remember it, it was on an Artifexian video though.

54 minutes ago, Spaceman17 said:

if they are in another solar system they have another type of propellants at their disposition, so they could be using a V2 to get to our solar system, or simply cannot get into space

I think we've discovered most elements in the universe that can't be made artificially, so I think it's a safe bet they have all of our materials, how much they have is a different story, anyone know the estimated composition of tau Ceti e?

[DeltaDizzy]

2 hours ago, Spaceception said:

I know there's a simple calculation to see the to get into orbit and escape the planet's gravity, but I can't remember it, it was on an Artifexian video though.

DONT CLICK IT

Spoiler

Apparently, it's 

Where:

G is gravitational constant,
M is the mass of the body at center,
R is radius of orbit.

V_orbit is measured in m/s.

After I found a calculator, the orbital velocity for a 100km circular orbif around Tau Ceti f appeared to be approx. 162.18 km/s

Assuming they have an ISP of 320s, a 500kg satellite. and a wet mass equal to that of a falcon 9 going to LEO, the DV is approx. 9,532.65 m/s(9.53 km/s)

I don't like math unless I can use a calculator.

Dv = 9.53 km/s for a 500kg satellite in a 100km circular orbit, from Tau Ceti f.

Edited August 10, 2017 by DeltaDizzy

[_Augustus_]

3 hours ago, Rakaydos said:

Except they needed something like a NOVA-class rocket just to get into orbit

To be fair, they could always rig up something like Sea Dragon (heck, they could scale it up even further if they wanted).

[Grand Ship Builder]

Too bad you have to choose between a very hot planet or a very cold one. If only they were a little bit closer to the habitable zone :|

[Spaceception]

10 minutes ago, Grand Ship Builder said:

Too bad you have to choose between a very hot planet or a very cold one. If only they were a little bit closer to the habitable zone :|

They are, they're practically brushing it however.

Tau Ceti e may be more like Venus due to its high mass, and close orbit.

Tau Ceti f on the other hand may be more habitable, I think it's mass is the same as e (Or they have the same lower limit), which is 3.9x the mass of Earth, which means the planet is more likely to have a thicker atmosphere, volcanic and tectonic activity, and strong magnetosphere. Unfortunately, it's also close to an asteroid belt, which may or may not cancel out its pros.

Edited August 10, 2017 by Spaceception

[DeltaDizzy]

8 minutes ago, Spaceception said:

*snip* I think it's mass is the same as e (Or they have the same lower limit), which is 3.9x the mass of Earth *snip*

f has a minimum mass of 6.6x mass of earth. I checked. Otherwise I couldn't have done this:

 

[Spaceception]

15 minutes ago, DeltaDizzy said:

f has a minimum mass of 6.6x mass of earth. I checked. Otherwise I couldn't have done this:

 

Are you sure? That mass estimate was from when they announced it in 2012, the mass estimates are much lower now.

[DeltaDizzy]

*google rocket equation calculator*

jk, I'm not going through that again

I'll give you the calculator links if you want.

[Terwin]

4 hours ago, Grand Ship Builder said:

Too bad you have to choose between a very hot planet or a very cold one. If only they were a little bit closer to the habitable zone :|

Plenty of space in there for an earth-sized planet once they get their detection sensitive enough to see if one is actually there...

 

[ProtoJeb21]

16 hours ago, Spaceception said:

They are, they're practically brushing it however.

Tau Ceti e may be more like Venus due to its high mass, and close orbit.

Tau Ceti f on the other hand may be more habitable, I think it's mass is the same as e (Or they have the same lower limit), which is 3.9x the mass of Earth, which means the planet is more likely to have a thicker atmosphere, volcanic and tectonic activity, and strong magnetosphere. Unfortunately, it's also close to an asteroid belt, which may or may not cancel out its pros.

I think it's possible that Tau Ceti e may resist a runaway greenhouse effect with a reflective cloud cover. However, it's easier to replicate with a tidally locked planet. Let's take EPIC 220221272f, a Super-Earth orbiting a small red dwarf. It is most likely tidally locked and has the same equilibrium temperature as Tau Ceti e. Water would evaporate on the front side and form a huge system of storms, potentially blocking out the worst of its star's light. This would reduce the amount of warm air being circulated around the planet, keeping other areas water-friendly. Tau Ceti e is not tidally locked and would likely have all its heat and clouds distributed evenly around the planet. Depending on how thick of an atmosphere (which may be reduced by large asteroid inpacts), the planet is either a warm terra with poles of water or a Venus-like planet. Potentially suitable for a tradigrade colony.

I also find more hope in Tau Ceti f, which may have a thick enough greenhouse effect to warm its equator to water-friendly temperatures. But on the subject of the asteroid belt, it may be more of a distant Kuiper Belt instead of an asteroid field close to Tau Ceti f. While Jovian and Super-Jupiter mass planets have been ruled out, a smaller Saturn-mass planet or two could possibly shield incoming asteroids and comets. However, this would possibly reduce chances for habitability on Tau Ceti e.

Long story short: the possibilities of life on both these planets is VERY up-in-the-air. Only future observations will determine how habitable these worlds are.