2020 the year in space prediction thread.

[Uncwilly]

2020 promises to be a bang-up year in space.
So, ladies and germs let's guess what will transpire this year. Please render your opinion on each of the following (guesses due by Jan 7.)

1. How many orbital (and to points beyond, like the moon, Mars, etc.) will happen in total? Not how many satellites, but successful launches?
2. How many new rocket systems will reach orbit (not those adapted from current orbital class rockets)?
3. Will each of the following get people into space, and if so, how many and how many launches: Space-X, Boeing, Virgin, and any other than RosCosmos?
4. Will Starship (Space-X) have a launch above 1 km, how many, max altitude, and will they get it into orbit?
5. How many orbital launches do you predict for any given company or nation?
6. Will Superheavy at least do a hop in 2020?
7. What will be the big surprise in spaceflight in 2020?
8. How many failed launches will we see in 2020? (Failure to reach orbit after dropped from carrier plane, after hold downs are released, or rocket destroyed on pad, etc.)?
9. What will be the fastest turn around for a Space-X Falcon 9 booster in this year?
10. How many interplanetary, moon, and other deep space (beyond lunar orbit) missions will successfully get away from earth this year (they don't have to get to their destination, but they can't be dead in transit)?
11. Which (if any) long time missions/craft die (Voyager, any Mars probe, New Horizons, Hubble, etc.)?

[ewmayer]

Since the thread as posted has garnered no replies, allow me to open things up a bit by extending the time window for bang-up things happening in space to a few years later, specifically to 2083:

Binary star V Sagittae to explode as very bright nova by century's end | Phys.org

V Sge has been systematically brightening by a factor of 10X, 2.5 magnitudes, from the early 1890s up until the last decade. This unprecedented behavior was confirmed with archival data collected from the database of the American Association of Variable Star Observers, AAVSO, showing V Sge brightening by nearly a factor of 10X, 2.4 magnitudes, from 1907 until the last few years.

"V Sge is exponentially gaining luminosity with a doubling time scale of 89 years," said Frank. "This brightening can only result with the rate of mass falling off the normal companion star increasing exponentially, ultimately because the binary orbit is in-spiraling rapidly."

"In anticipation of this fast decaying of the orbit, the fate of V Sge is sealed," stated Schaefer. "The critical and simple physics are derived from V Sge having the companion star being much more massive than the white dwarf star, so forcing the rate of mass transfer to rise exponentially. Anticipating the next few decades, V Sge will in-spiral at a rapid pace with increasing brightness. Inevitably, this in-spiral will climax with the majority of the gas in the normal star falling onto the white dwarf, all within the final weeks and days. This falling mass will release a tremendous amount of gravitational potential energy, driving a stellar wind as never before seen, and raise the system luminosity to just short of that of supernovae at peak."

This explosive event will have peak brightness over a month, with two stars merging into one star. The end result of the merger will produce a single star with a degenerate white dwarf core, a hydrogen-burning layer, surrounded by a vast gas envelope mostly of hydrogen.

"From this critical new input of the doubling time scale of 89 years, it becomes possible to directly calculate the future evolution of V Sge, all using standard equations describing the many physical mechanisms involved," said Schaefer.

The calculations give a robust answer to the brightness with the in-spiral merger happen for the final merge event will be around the year 2083. "The uncertainty in this date is ±16 years, arising mostly from not having a perfect measure of the doubling time scale due to the large intrinsic jitter of the brightness in the historical record," said Frank. "Therefore, the merge will be approximately between 2067 and 2099, most likely near the middle of this range."

"Thus, V Sge will appear startlingly bright in the night sky, said Schaefer. "This is substantially brighter than the all-time brightest known nova (at -0.5) just over a century ago, and the last time any 'guest star' appeared brighter was Kepler's Supernova in the year 1604."

[chris2be8]

One thing that doesn't say is if the white dwarf is likely to accrete enough matter to take it over the Chandrasekhar limit so it collapses and becomes a type 1a supernova. That would be even brighter.

Chris

[ewmayer]

Originally Posted by chris2be8

One thing that doesn't say is if the white dwarf is likely to accrete enough matter to take it over the Chandrasekhar limit so it collapses and becomes a type 1a supernova. That would be even brighter.

Chris

The system is unusual in the main sequence star being significantly more massive than the white dwarf so that's an interesting possibility, but it's easy enough to check - per Wikipedia:

V Sagittae or V Sge is a cataclysmic variable binary star system in the constellation Sagitta that is expected to go nova and briefly become the most luminous point of light in the Milky Way and the brightest stars in our sky around the year 2083. The system is composed of a main sequence star of about 3.3 solar masses and a white dwarf of about 0.9 solar masses. The fact that the white dwarf is smaller than its companion is highly unusual, and V Sge is the only super soft X-ray source nonmagnetic cataclysmic variable found so far.

V Sge has brightened by a factor of 10 over the last century, and based on research reported in 2020, it is expected to continue to brighten and briefly become the brightest star in the sky sometime around 2083, plus or minus about 11 years. Over the last few months and days the pair will coalesce and go nova, eventually becoming a red giant star.

The stars currently orbit each other about every 0.514 days, and eclipse each other each orbit. The pair is in the late stages of an in-spiral, and the period is increasing at a rate of -4.73 * 10^-10 days/cycle.

Chandrasekhar limit ~= 1.4 solar masses, but note this assumes quasi-equilibrium, whereas here we have the highly active hydrodynamics of a star about to go nova. It's such a basic behavioral issue that I'm sure the astronomers studying and modeling the system have considered it - I expect that most of the infalling mass in the terminal merger stage will get blown off again as the system goes nova ... but I see that this would be a highly unusual amount of mass loss for a nova. Again, Wikipedia:

Hydrogen fusion may occur in a stable manner on the surface of the white dwarf for a narrow range of accretion rates, giving rise to a super soft X-ray source, but for most binary system parameters, the hydrogen burning is unstable thermally and rapidly converts a large amount of the hydrogen into other, heavier chemical elements in a runaway reaction, liberating an enormous amount of energy. This blows the remaining gases away from the surface of the white dwarf surface and produces an extremely bright outburst of light.
...
In spite of their violence, usually the amount of material ejected in novae is only about ​1⁄10,000 of a solar mass, quite small relative to the mass of the white dwarf. Furthermore, only five percent of the accreted mass is fused during the power outburst. Nonetheless, this is enough energy to accelerate nova ejecta to velocities as high as several thousand kilometers per second—higher for fast novae than slow ones—with a concurrent rise in luminosity from a few times solar to 50,000–100,000 times solar. In 2010 scientists using NASA's Fermi Gamma-ray Space Telescope discovered that a nova also can emit gamma-rays (>100 MeV).

Potentially, a white dwarf can generate multiple novae over time as additional hydrogen continues to accrete onto its surface from its companion star. An example is RS Ophiuchi, which is known to have flared six times (in 1898, 1933, 1958, 1967, 1985, and 2006). Eventually, the white dwarf could explode as a Type Ia supernova if it approaches the Chandrasekhar limit.

Interestingly, I found no discussion of this possibility in the "technical details" PDF linked in the original Phys.org article. Hmmm......

[xilman]

I´m skeptical myself, as is a professional astronomer with whom I exchanged emails on the subject about an hour ago. He has roughly 40 years experience observing and analyzing observations of objects like V Sge. We both find the few-decades timescale rather implausible which has been chosen to make a good news story.

That said, he finds it interesting and, at my instigation, is likely to contribute to a pro-am collaboration with the BAA-VSS.


M31N 2008-12a is another fascinating recurrent nova which is likely to go supernova in the near future. Despite being in the Andromeda galaxy it is quite likely to become visible to the naked eye.

[Dr Sardonicus]

According to the details listed here, the white dwarf has mass between 0.8 and 0.9 times the mass of the sun, and its companion has mass between 3.1 and 3.5 times the mass of the sun.

The Chandrasekhar limit is about 1.4 times the mass of the sun. Pile more mass than that on the white dwarf, and gravity overcomes "electron degeneracy pressure." The white dwarf collapses further, the carbon and oxygen become able to fuse into iron, and -- BOOM!

It's hard for me to see the mass not reaching the Chandrasekhar limit, if not during accretion, then after the white dwarf is inside the companion, as is predicted to happen.

It is also not clear to me why, if the process for V Sagittae is expected to involve accreted material getting blown off the white dwarf fast enough to keep it below the limit, why this doesn't happen with white dwarf stars that do go Type 1a supernova. Is it the rapid inspiralling? I don't know. I have so far not succeeded in finding an explanation.

Also -- doesn't the companion have its own stellar core? If it does, and the white dwarf meets it, I would expect the result to be -- BOOM!

[xilman]

Originally Posted by Dr Sardonicus

According to the details listed here, the white dwarf has mass between 0.8 and 0.9 times the mass of the sun, and its companion has mass between 3.1 and 3.5 times the mass of the sun.

The Chandrasekhar limit is about 1.4 times the mass of the sun. Pile more mass than that on the white dwarf, and gravity overcomes "electron degeneracy pressure." The white dwarf collapses further, the carbon and oxygen become able to fuse into iron, and -- BOOM!

It's hard for me to see the mass not reaching the Chandrasekhar limit, if not during accretion, then after the white dwarf is inside the companion, as is predicted to happen.

It is also not clear to me why, if the process for V Sagittae is expected to involve accreted material getting blown off the white dwarf fast enough to keep it below the limit, why this doesn't happen with white dwarf stars that do go Type 1a supernova. Is it the rapid inspiralling? I don't know. I have so far not succeeded in finding an explanation.

Also -- doesn't the companion have its own stellar core? If it does, and the white dwarf meets it, I would expect the result to be -- BOOM!

There is little doubt that something interesting is likely to happen quite soon.

It is the ~65 year timescale which is open to serious questioning.

[ewmayer]

Originally Posted by Dr Sardonicus

The Chandrasekhar limit is about 1.4 times the mass of the sun. Pile more mass than that on the white dwarf, and gravity overcomes "electron degeneracy pressure." The white dwarf collapses further, the carbon and oxygen become able to fuse into iron, and -- BOOM!

It's hard for me to see the mass not reaching the Chandrasekhar limit, if not during accretion, then after the white dwarf is inside the companion, as is predicted to happen.

That neglects the interesting things that happen when one piles even a modest amount - the "nova" link I re'd cited on the order of 1/10,000 solar masses for a typical nova - of fusion-ready material onto the surface of a white dwarf. Given the propensity of such accreted material to flash into rapid-burn mode, I'm wondering how the 2083-nova predictors get to their conclusion that nearly all the mass of the 3.3-solar-mass star will end up merging with the white dwarf. I see 2 plausible alternate scenarios:

1. Once the accretion rate passes a threshold of magnitude similar to that of a normal nova event, just such will happen, and the resulting blowing-off will temporarily reverse the accretion process. A quasi-regular sequence of pulsations could be the result, each of which leaves the white dwarf that much more massive, eventually culminating in a Type 1a SN.

2. The unusual nature of the system leads to an unusually energetic nova event which leaves the white dwarf still below the Chandrasekhar limit but completely disrupts the main sequence star, leaving it as a giant outward-billowing nebula.

The "unusual nature" aspect is a 2-edged sword here: It makes the system very interesting, but at the same time it makes the kind of simplistic "extrapolation from normal nova behavior" modeling described in the PDF very fraught. I was expecting such a firm-sounding timing prediction to be underpinned by highly detailed supercomputer simulations of the immensely complex hydrodynamics of such a system, and was disappointed to find no such thing - from the PDF:

The future of V Sge is straight forward to predict with good accuracy by the simple use of standard equations that model all the various physical mechanisms involved. The idea is to start with the well-known current system properties, use these properties to calculate how each of the properties will change in the next time interval, add these changes to get the system properties for a year or a day from now, and keep repeating this for time intervals marching o ̇ into the future. Initially, it imay be adequate to have one-year intervals, but as the end approaches, shorter and shorter intervals are needed. The changes in angular momentum, semi-major axis, and Roche lobe size are governed by the mass transfer rates, and the changes in the mass transfer rates are governed by the rate of decrease for the Roche lobe radius. So, by propagating the system into the future, year-by-year and day-by-day, the future properties of V Sge can be predicted. This has been done by setting up a system of first-order differential equations governing the binary separation, the masses of the binary component stars, and the radius of the companion star. With these equations we can advance in time from some specified initial state and thus predict the evolution of the system.

Ooh - "a system of first-order differential equations" which is alleged to "model all the various physical mechanisms involved". Sorry, not even close! Do not pass Go, do not collect $200.

[xilman]

Originally Posted by ewmayer

1. Once the accretion rate passes a threshold of magnitude similar to that of a normal nova event, just such will happen, and the resulting blowing-off will temporarily reverse the accretion process. A quasi-regular sequence of pulsations could be the result, each of which leaves the white dwarf that much more massive, eventually culminating in a Type 1a SN.

This is exactly what is happening with M31N 2008-12a. The pulsations occur with an average frequency of just under a year but the period varies by up to a month or so. The "blowing off" has also been observed by its effect on the interstellar medium.

Despite being so faint at minimum light, meaning we can´t see the mass-losing companion nor determine the orbital period of the system, the intensity of each outburst and its frequency sets a lower limit on the accretion rate. The radial velocities measured from the spectrum during outburst and the size of the ejected material, which is easily big enough to be measured from here, set tolerably good limits on the mass of the ejecta at each eruption. Well understood nuclear physics and Newtonian gravitation then allows one to calculate the annual mass gain on the white dwarf.

Searching on the name of the recurrent nova will turn up several authoritative yet easily read papers. Even better, most of them have nice pictures to look at if you have difficulty following the text in its finest detail.

[TommyJ]

2021 looks like it could still be more exciting in terms of new launches. Of course, 2020 had its own quirks (let's call it quirks) that allowed a lot of people to watch some interesting launches. China has more than 40 launches scheduled for 2021. Ariane 6, New Glenn, Vulcan-Centaur were also supposed to be launched in 2021. But the launch of the James Webb Space Telescope is probably especially interesting. This seems to be one of the most anticipated events in this area.

[firejuggler]

I 'm looking forward Perseverance landing in february