Astronomy

[Dreamwoven]

You can also use Lagrange Points to travel the solar system with minimum fuel requirements: http://www.universetoday.com/131953/...sport-network/. Only slightly slower but much more efficient.

"But it turns out there’s another way you can travel from planet to planet in the Solar System, using a fraction of the energy you would use with the traditional Hohmann transfer, and that’s using Lagrange points.

We did a whole article on Lagrange points, but here’s a quick refresher. The Lagrange points are places in the Solar System where the gravity between two objects balances out in five places. There are five Lagrange points relating to the Earth and the Sun, and there are five Lagrange points relating to the Earth and the Moon. And there are points between the Sun and Jupiter, etc.


Three of these points are unstable. Imagine a boulder at the top of a mountain. It doesn’t take much energy to keep it in place, but it’s easy to knock it out of balance so it comes rolling down.

Now, imagine the whole Solar System with all these Lagrange points for all the objects gravitationally interacting with each other. As planets go around the Sun, these Lagrange points get close to each other and even overlap.

And if you time things right, you can ride along in one gravitationally balanced point, and the roll down the gravity hill into the grasp of a different planet. Hang out there for a little bit and then jump orbits to another planet.

In fact, you can use this technique to traverse the entire Solar System, from Mercury to Pluto and beyond, relying only on the interacting gravity of all these worlds to provide you with the velocity you need to make the journey."

[Dreamwoven]

http://www.universetoday.com/131970/...ifreeze-ocean/

"The evidence keeps growing for a large subsurface ocean at Pluto, which also provides clues how the iconic ‘heart’ of Pluto was formed.

We reported in early October that thermal models of Pluto’s interior and tectonic evidence suggest an ocean may exist beneath Pluto’s heart-shaped Sputnik Planitia. Now, new research on data from the New Horizons mission shows more indications of an ocean just below Pluto’s surface that consists of a slushy, viscous liquid, kept warm from Pluto’s interior and a hint of anti-freeze.

“As far as we can tell, there’s no tidal heating helping to keep the ocean liquid,” Francis Nimmo from UC Santa Cruz told Universe Today. He is the first author of a paper on the new findings published today in Nature. “The main heat source keeping the ocean liquid is radioactive decay in Pluto’s rocky interior, although it certainly helps if there is an ‘antifreeze’ present.”

Nimmo said he suspects the ocean is mostly water with ammonia acting as an antifreeze. This subsurface ocean is also bulging, similar to the ‘mascons’ on the Moon, putting stress on Pluto’s icy outer shell, causing fractures consistent with features seen in the New Horizons images.

Another paper also published in Nature today from James Keane at the University of Arizona, also shows how a bulging subsurface ocean made Pluto’s heart ‘heavy,’ reorienting Pluto on its axis, so that Pluto’s heart is always pointing away from the moon Charon."

[Dreamwoven]

http://www.universetoday.com/107598/...e-kuiper-belt/

Future of the Kuiper Belt:
When he initially speculated about the existence of a belt of objects beyond Neptune, Kuiper indicated that such a belt probably did not exist anymore. Of course, subsequent discoveries have proven this to be wrong. But one thing that Kuiper was definitely right about was the idea that these Trans-Neptunian Objects won’t last forever. As Mike Brown explains:

We call it a belt, but it’s a very wide belt. It’s something like 45 degrees in extent across the sky – this big swath of material that’s just been churned and churned by Neptune. And these days, instead of making a bigger and bigger body, they’re just colliding and slowly grinding down into dust. If we come back in another hundred million years, there’ll be no Kuiper Belt left.
Given the potential for discovery, and what up-close examination could teach us about the early history of our Solar System, many scientists and astronomers look forward to the day when we can examine the Kuiper Belt in more detail. Here’s hoping that the New Horizons mission is just the beginning of future decades of research into this mysterious region!

We have many interesting articles here at Universe Today on the subject on the Outer Solar System and Trans-Neptunion Objects (TNOs).

And be sure to check out this article on the planet Eris, the latest dwarf planet and the largest TNO to be discovered.

And astronomers are expecting to discover two more large planets in our Solar System.

[YesNo]

It is interesting that we can detect Kuiper belts around other stars. I wonder how that was done. We can barely detect exoplanets around those stars.

Using the Lagrange points seems like a nice way to move around the solar system for research purposes. The craft should get energy somewhere, perhaps from the Sun so that it could keep sending back data continually. If it is made small enough like those cubesats, research about the solar system could be very inexpensive.

[Dreamwoven]

There may be a problem with that, as space telescopes are likely to be located at Lagrange points: Spitzer is likely to be located at one. Traffic congestion? Or perhaps not, I have no idea how large Lagrange points are. They of course move about as they are based on the movement of the planets...

[Dreamwoven]

EarthSky often has quite useful information on all things, not just space. See http://earthsky.org/space/what-makes...round-the-moon

What makes a halo around the sun or moon? There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.

Why is it called a 22-degree halo? Because the ring has a radius of approximately 22° around the sun or moon.

[YesNo]

Come to think of it, clouds are mysterious. And they are not all alike which adds to the mystery.

[Dreamwoven]

http://dawn.jpl.nasa.gov/news/

The Dawn Mission has been exploring the dwarf planet Ceres for the lat 8 months. Now it will be going higher to get more views of it.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/...s-cryo-volcano

This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past," Ruesch said.

For more details on this study, see:
http://www.nasa.gov/feature/goddard/...s-cryo-volcano

Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn's visible and infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres' crust does contain a significant component of water-ice. This is consistent with a study of Ceres' diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres' past. Craters that are roughly polygonal -- that is, shapes bounded by straight lines -- hint that Ceres' crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet's various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both -- a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters' depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

"The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution," Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres' crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet's crust indicates Ceres' surface material has been altered by a global process involving water.

Although Ceres' phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, "pancake"-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

"In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu," Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres' surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team."

[YesNo]

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

[Dreamwoven]

It does look like a volcano, but why only one such volcano on Ceres? Have they found out what those bright spots are?

Yes, they found out what the bright spots were ages ago. Need to go back and look them up.

[Dreamwoven]

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

[Dreamwoven]

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spa...-to-ring-graze.

Lots to learn and discuss here.

[YesNo]

There is a wikipedia website on this: https://en.wikipedia.org/wiki/Bright_spots_on_Ceres

Mostly salt, it seems.

The Dawn probe will now go into perpetual orbit round Ceres even after its lost all its capabilities.

I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

[Dreamwoven]

Sometimes Earth/Sky comes up with some interesting posts. Here is one on Cassini, the probe of Saturn: http://earthsky.org/space/saturn-spa...-to-ring-graze.

Lots to learn and discuss here.

While it’s easy to feel nostalgic about the coming end of NASA’s wonderful Cassini mission to Saturn (source of so many incredible images), excitement is now building as the mission prepares to enter its grand finale year in 2017. NASA engineers have been pumping up the spacecraft’s orbit around Saturn this year to increase its tilt with respect to the planet’s equator and rings. On November 30, 2016, following a gravitational nudge from Saturn’s moon Titan, Cassini will go into an orbit that’ll send it just past the unexplored region at the outer edge of Saturn’s main rings. It’ll continue grazing the rings between November 30 and April 22, 2017, circling high over and under the poles of Saturn, diving past the rings every seven days, a total of 20 times. Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, said:

We’re calling this phase of the mission Cassini’s Ring-Grazing Orbits, because we’ll be skimming past the outer edge of the rings.

And that’s only the beginning of Cassini’s grand finale in 2017.

First, though, why is the mission ending? Cassini has been in space for nearly 20 years. It launched from Earth in 1997 and has been touring the Saturn system – weaving among the planet’s rings and moons – since 2004. Its discoveries include a global ocean within Enceladus and liquid methane seas on Titan, but even those amazing discoveries pale next to the dramatic consciousness shift space fans have experienced over the years of this mission. Prior to Cassini, we had only glimpsed Saturn and its rings and moons. Now we see them, in all their intricate and profound beauty.

But, now, the Cassini spacecraft is running low on fuel. And so the mission must end, but not before it run through a year-long lists of “firsts” at Saturn. That’s following a series of “lasts,” by the way, related to Saturn’s moons, in 2016.

Simply put, before its end, Cassini has more science to do. For example, on many of the upcoming passes through the ringplane, Cassini’s instruments will attempt to sample ring particles and molecules of faint gases close to the rings, directly. Linda Spilker said:

… we have two instruments that can sample particles and gases as we cross the ringplane, so in a sense Cassini is also ‘grazing’ on the rings.

During the first two orbits, the spacecraft will pass directly through an extremely faint ring produced by tiny meteors striking the two small moons Janus and Epimetheus. Ring crossings in March and April will send the spacecraft through the dusty outer reaches of the F ring. Earl Maize, Cassini project manager at JPL, said:

Even though we’re flying closer to the F ring than we ever have, we’ll still be more than 4,850 miles (7,800 km) distant. There’s very little concern over dust hazard at that range.

The concern about dust will increase, though, after April, as Cassini executes the later phases of its grand finale. Ultimately, Cassini will pass as close as 1,012 miles (1,628 km) above Saturn’s cloudtops as it dives repeatedly through the narrow gap between Saturn and its rings.

The mission’s planned end will come on September 15, 2017, when the spacecraft will plunge into Saturn’s dense atmosphere.

For now, though, NASA says, some preparatory work remains:

To begin with, Cassini is scheduled to perform a brief burn of its main engine during the first super-close approach to the rings on December 4. This maneuver is important for fine-tuning the orbit and setting the correct course to enable the remainder of the mission…

To further prepare, Cassini will observe Saturn’s atmosphere during the ring-grazing phase of the mission to more precisely determine how far it extends above the planet. Scientists have observed Saturn’s outermost atmosphere to expand and contract slightly with the seasons since Cassini’s arrival. Given this variability, the forthcoming data will be important for helping mission engineers determine how close they can safely fly the spacecraft.

Bottom line: The Cassini spacecraft has been shifting its orbit throughout 2016, preparing for the mission’s grand finale in 2017. On November 30, it’ll begin a series of 20 orbits that fly high above and below Saturn’s poles, plunging just past the outer edge of the main rings.

[Dreamwoven]

I checked that site, but it seems that they don't really know. They mentioned: "...it is material with a high level of reflection, and suggested ice and salt as possibilities." It still appears to be speculation.

In that case, everything in space research is just speculation. At some point we have to accept that. There just is no 100 percent confirmation of much space exploration.

Nevertheless, I shall continue to observe.

Thi is from nature.com:
The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater1. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate1, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates2, 3, 4. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus5. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.