More Nearby Exoplanets

Some interesting news from a research team using the HARPS instrument to observe Gliese 667: Gliese 667 C may host as many as five exoplanets (two have been previously confirmed), with three falling within the habitable zone. Masses are all several times that of Earth, but none appear to be Neptune-mass objects. Lower bounds for all five object candidates characterize them as super-Earths, or massive terrestrials until we know more.

Gliese 667 C is a member of an interesting trinary solar system, only 22 light years away. Gliese 667 C orbits the A-B pair at a distance of about 230 AU, which is some 8 times more distant than Neptune is from our sun. The A-B pair stars are both orange K-class stars, smaller and cooler than our sun, while Gliese 667 C is dimmer and cooler yet, being a reddish M-class dwarf star.

All detected or candidate planets orbiting Gliese 667 C are in close, rapid orbits, taking from 7 (innermost – b) to 91 (outermost confirmed – d) days to orbit the star. In our own solar system, Mercury has an 88-day orbit, so these bodies fall within a comparable star-hugging distance. Despite the short years and due to the much cooler star, we have some excellent candidates for habitable worlds.

Gliese 667 is listed in Proxima Centauri Games’ newly-released Near Star Map Android app, along with all nearby stars (and their exoplanet information) out to 35 light-years form Earth.

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Mid-June Orbital News

Two events of note are in progress. Of greatest significance is the successful launch and docking of Shenzhou-10, a manned Chinese mission to orbital station Tiangong-1, as China continues to steadily advance its space program.

In the meantime, the latest ESA ATV freight mission to the ISS has docked successfully. ATV operations are of continued interest not only for station supply, but because ATV hardware is likely to be integrated into upcoming joint manned projects using the Lockheed-Martin Orion.

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Blue Marbles in the Distance?

More from one of the Kepler teams: Kepler-62 appears to have two planets with orbits in its habitable zone. Kepler-62e and Kepler-62f are both larger than Earth, but not by much: about 1.6 and 1.4 times Earth’s radius respectively. Masses are not yet known with precision.

Kepler-62 is a cool K star, so the outer of these two worlds orbits about as far out as Venus in our solar system, yet is still chilly, possibly mostly an ice world. The inner of the two, Kepler-62e, may be rather warm, with a need for cloud cover to keep the surface cool enough for liquid water. However, for both, the potential for liquid water certainly exists assuming atmospheric conditions are favorable.

Unfortunately, being in the Kepler field in Lyra, these worlds are of course very distant. Kepler-62 is about 1,200 light-years away.

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Voyager 1 Has Left the System

The accepted boundary defining the edge of our solar system is the heliopause, where the solar wind from the Sun is overwhelmed by the interstellar medium and magnetic fields. NASA teams monitoring Voyager 1′s operating instruments have been reporting changes for quite a few months, but now a report released by the American Geophysical Union indicates that Voyager project scientists have submitted a paper to the journal Geophysical Research Letters indicating the heliopause has been crossed and readings from the spacecraft now appear to be of the interstellar medium. If this finding is verified, Voyager 1 will have become the first-man-made object to return data from beyond the heliopause.

Voyager 1 has made an epic journey since launch on 5 September 1977. Its Jupiter encounter took place in 1979, Saturn encounter in 1980. It was the first spacecraft to provide data from encounters with these planets. Emphasizing the speed with which the Voyager 1 probe was sent, the Galileo probe took from 1989 to 1995 to reach Jupiter.

Science data from Voyager 1 will decline in the coming years, as the radiothermal generators on board continue to gradually deliver less power. By 2025 no science instruments are expected to be able to operate. In some 40,000 years, the craft is expected to pass 1.6 light-years from the star Gliese 445 (AC+79 3888), which is presently 17.6 light-years distant but rapidly approaching our solar system. At the time of its “encounter” with Voyager 1, Gliese 445 will be nearer to our sun than Proxima Centauri is now.

Bon voyage, Voyager 1.

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CRS-2 Dragon Up

Entirely the opposite of a damning development, I missed the launch of SpaceX’s CRS-2 Dragon mission yesterday because apparently the mainstream media barely took notice. As in, SpaceX launched successfully again, and it wasn’t news.

SpaceX, of course, will point out rather that their fifth successful consecutive launch of the Falcon 9 is a statement about its continued reliability. Statistically, they’re bound to have a problem eventually. My hope is that it won’t slow them down at all. In my opinion, SpaceX is still the best hope we have for space flight in general.

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Kepler-37b Worth Notice

I’m becoming immune to the near-constant onslaught of exoplanet news, which itself should be considered a pretty awesome development. There’s just so much of it, from teams using both radial-velocity and transit methods, and the Kepler data is providing so much information it’s hard now to think that anyone seriously doubted that planets were necessarily commonplace.

However, some of the most recent data on the Kepler-37 system is absolutely fascinating because the team from the Harvard-Smithsonian Center for Astrophysics has really pushed the boundaries of what we’re able to detect. Kepler-37 is a G-type star about 215 light-years away in the Kepler field, located in the constellation Lyra. Kepler-37d was interesting a year ago. It has about twice Earth’s diameter, though it’s in a hot 40-day orbit, closer to its star than Mercury is to our sun. Kepler-37c is in a 21-day orbit with a diameter of about 0.75 Earths. That was amazing recently, too: a clearly rocky body smaller than Earth (though still far too close to its star to be hospitable).

The kicker is the data on Kepler-37b, which shows it to be in a 13-day orbit. Obviously very hot. But its diameter is officially estimated at 3865km. That’s barely larger than our Moon! It is completely stunning that we’ve been able to detect such a small body 215 light-years away, and although we cannot necessarily use these same methods broadly, this discovery still represents a dramatic technological advance.

Further, it is highly suggestive that small bodies like Kepler-37b and c are at least as common as the other larger and more massive types of exoplanets we’re more readily able to detect. Space is full of terrestrial rocks. Someday soon we will spot one in a habitable zone. I suspect based on the sheer volume of the data from Kepler, we’ll spot something like that in the distant Kepler field before we find anything similar in our own backyard.

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And a Small Hit

Hardly consolation to the thousand or so injured in Russia today near Chebarkul in Chelyabinsk, but the the object that struck was rather small. Preliminary estimates suggest it was a 15m object massing only about 7000 tons, and exploded in the atmosphere on its way down at a very shallow angle, which would have been the cause of the pressure waves that shattered so much glass in the area, injuring many hundreds of people. One fragment is known to have gouged out a 6m crater. A larger object would have been a kinetic strike with the power of a nuclear device, which surely would have resulted in orders of magnitude more devastation and deaths.

This should be a huge wake-up call that we need to be acting on planetary defense, and now. A larger and much more devastating rock could surprise us with a strike practically at any time, anywhere on the earth’s surface. Of course the deniers of reality were quick to respond: Zhirinovsky put a trademark Russian-paranoia spin on the situation by cleverly blaming a test of an American weapon. Stick to blaming the terrorists, Vlad.

I’m confident the B612 Foundation will have some things to say about this event.

UPDATE: Here is some data from Dr. Peter Brown, Director – Centre for Planetary Science and Exploration at the University of Western Ontario, relayed through the Rocky Mountain chapter of the Mars Society.

Main flare/airburst was 03:20:26 UT on Feb 15, 2013; the fireball began ablation about 30 secs before this time. Entry was at a very shallow angle, less than 20 degrees.
Strike completely unrelated to the close approach of 2012 DA14 today.
Energy still being determined, possibly ~300kT TnT equiv. Almost certainly in excess of 100kTons, making it the largest recorded event since the 1908 Tunguska explosion.
The fireball entered the atmosphere at 18 km/s.
The pre-impacting asteroid was about 15 meters in diameter and had a mass of ~7000 tonnes.
Cylindrical pressure wave that did most of the damage probably was in excess of 5000 Pa overpressure, which propagated directly to the ground due to the very shallow angle of impact.

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Another Near Miss

The near-Earth asteroid 2012 DA14 swings within 18,000km as it passes Earth on 15 February. It’s a little rock, only 40m across, but it could have done some serious local damage had it hit us.

2012 DA14 is actually considered not hazardous, based on its orbit. It’ll be near Earth again in about 30 years, and based on Minor Planet Center data won’t be nearly as close.

Earth’s role as a target in the “cosmic shooting gallery” is the theme of a game called “Torino Warning”, produced by Proxima Centauri Games, an indie game studio in Colorado that makes space games. This Android game is available on Google Play and in your PC browser right now.

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An Opportunity in Comet C/2012 S1?

I’ve just noticed the recent news that Comet C/2012 S1 (ISON) is on its way to the inner solar system, and has the possibility of being a spectacular visitor. Apparently this object is on its first visit to the inner solar system. Some of the evidence for this is that it already has a very significant tail (64,000 km) while still beyond the orbit of Jupiter. This means the comet is chock-full of volatiles that can be expelled by the Sun’s energy at that distance. Since those volatiles, once blown off, don’t regenerate, we can be pretty certain the object hasn’t previously been this close to the Sun.

This raises some questions about whether its orbit can be traced back, and some insight gained about very distant objects in the outer system, far beyond the Kuiper Belt. There are many other fascinating science opportunities here, but I digress.

In November this year, Comet C/2012 S1′s perihelion is expected to be about 1 million km from the Sun’s surface, so it’s going to get pretty cooked. It should kick off a lot of material, after which it will be on its way back out, but from the looks of the orbit diagram I’ve seen, we on Earth should get a pretty nice view. The comet is expected to be visible through February 2014, and astronomers are already talking about the potential of it being bright enough and near enough to be visible in our daylight sky.

Now, if seeing something like that doesn’t inspire people about space, I don’t know what will. Nature’s offering us a free chance for some really great public relations. I’m hopeful that many space advocacy groups can seize this opportunity.

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Tau Ceti System Revealed in Existing Datasets?

A team headed by M. Tuomi at the University of Hertfordshire has sifted existing radial velocity data for Tau Ceti from multiple sources and come up with a pattern that suggests a system of five planets, with periods of 13.9, 35.4, 94, 168, and 640 days and minimum masses of 2.0, 3.1, 3.6, 4.3, and 6.6 Earth masses, respectively. Tau Ceti is, of course, a sunlike star (G8V) with no stellar companions (unlike triplet Alpha Centauri) only 12 light-years away. The planet with the 168-day period falls inside the star’s potential habitable zone.

The formal paper is available online here.

These exciting findings will need to be confirmed, but much like the recent discovery at Alpha Centauri B, this system is finally one that we could really conceive of our civilization reaching with a fast robotic probe within the next few generations.

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