Posted on by Fraser Cain

Podcast: The End of the Universe Part 1: The End of the Solar System

planetary nebula
Planetary nebula. The future for our Sun. Image credit: Hubble

This is a show we wanted to do since we started Astronomy Cast but we always thought it was too early. We wanted you to know that we’re positive, happy people with enthusiasm for astronomy and the future. It’s time for some sadness. It’s time for a grim look to see what the future holds for the Universe. This week we stay close to home and consider the end of humanity, the Earth, the Sun, and the entire Solar System. Next week we’ll extend out to the very end of the Universe.

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The End of the Universe Part 1: The End of the Solar System – Show notes and transcript

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Posted on by Fraser Cain

The Earth’s Cities at Night

You only have to walk outside at night, look up and not see the Milky Way to know that light pollution is a problem. And seen from space at night, the Earth’s surface glows with the light of millions of homes, buildings, cars and streetlights. Seen at night, our impact on the Earth is immediate and obvious.

A few years ago, NASA and NOAA compiled a complete world map of the nighttime Earth, using 9 months of data collected by satellites. This “Night Lights” image is pretty famous, and widely circulated around the Internet.

There’s a great article at NASA’s Earth Observatory that describes how they capture these night images of the Earth’s surface. You can also see many of the best images taken so far.

Click here to read the article.

Posted on by Fraser Cain

Discovery of Pluto

Once the planet Uranus was discovered, astronomers have suspected that there are probably more planets in the Solar System. Astronomers used Newtonian mechanics to predict Neptune from its perturbations of Uranus’ orbit. German astronomer Gottfried Galle found Neptune exactly where calculations predicted it should be.

Now that they knew the method worked, astronomers set about finding other planets beyond Neptune. In the late 19th century, astronomers were starting to suspect that another body was pulling on both Uranus and Neptune, and so they tried to calculate its position, and then go look for it.

Percival Lowell, a wealthy Bostonian who founded the Lowell observatory in Flagstaff, Arizona, took up that search. He searched from 1905 all the way up to his death in 1915, and he never found it.

The job then turned to a young astronomer named Clyde W. Tombaugh – a 22-year old Kansas farm boy. Tombaugh spent the better part of a year staring at two photographic plates capturing the same region of sky at two different points in time.

Using a tool called a blink comparator, Tombaugh finally turned up images of Pluto moving in 1930. It turns out there had been evidence of Pluto in earlier photographs, but nobody had noticed it yet.

As the discoverers, Tombaught and his team were given the honor of naming Pluto. In the end, they settled on the name Pluto, suggested by a British school girl.

Posted on by Ian O'Neill

Self-Healing Computers for Damaged Spaceships

View of the Westar 6 satellite while Dale Gardner retrieves it during STS-51-A in 1984 (NASA)

What happens when a robotic space probe breaks down millions of miles away from the nearest spacecraft engineer? If there is a software bug, engineers can sometimes correct the problem by uploading new commands, but what if the computer hardware fails? If the hardware is controlling something critical like the thrusters or communications system, there isn’t a lot mission control can do; the mission may be lost. Sometimes failed satellites can be recovered from orbit, but as there’s no interplanetary towing service for missions to Mars. Can anything be done for damaged computer systems far from home? The answer might lie in a project called “Scalable Self-Configurable Architecture for Reusable Space Systems”. But don’t worry, machines aren’t becoming self-aware, they’re just learning how to fix themselves…

When spacecraft malfunction on the way to their destinations, often there’s not a lot mission controllers can do. Of course, if they are within our reach (i.e. satellites in Earth orbit), there’s the possibility that they can be picked up by Space Shuttle crews or fixed in orbit. In 1984 for example, two malfunctioning satellites were picked up by Discovery on the STS-51A mission (pictured above). Both communications satellites had malfunctioning motors and couldn’t maintain their orbits. In 1993 Space Shuttle Endeavour (STS-61) carried out an orbital mirror-change on the Hubble Space Telescope. (Of course, there’s always the option that top secret dead spy satellites can be shot down too.)

Although both of the retrieve/repair mission examples above most likely involved mechanical failure, the same could have been done if their onboard computer systems failed (if it was worth the cost of an expensive manned repair mission). But what if one of the robotic missions beyond Earth orbit suffered a frustrating hardware malfunction? It needn’t be a huge error either (if it happened on Earth, the problem could probably be fixed quickly), but in space with no engineer present, this small error could spell doom for the mission.

So what’s the answer? Build a computer that can fix itself. It might sound like the Terminator 2 storyline, but researchers at the University of Arizona are investigating this possibility. NASA is funding the work and the Jet Propulsion Laboratory is taking them seriously.

Ali Akoglu (assistant professor in computer engineering) and his team are developing a hybrid hardware/software system that may be used by computers to heal themselves. The researchers are using Field Programmable Gate Arrays (FPGAs) to create self-healing processes at the chip-level.

FPGAs use a combination of hardware and software. Because some hardware functions are carried out at chip-level, the software acts as FPGA “firmware”. Firmware is a common computer term where specific software commands are embedded in a hardware device. Although the microprocessor processes firmware as it would any normal piece of software, this particular command is specific to that processor. In this respect, firmware mimics hardware processes. This is where Akoglu’s research comes in.

The researchers are in the second phase of the project called Scalable Self-Configurable Architecture for Reusable Space Systems (SCARS) and have set up five wireless networked units that could easily represent five cooperating rovers on Mars. When a hardware malfunction occurs, the networked “buddies” deal with the problem on two levels. First, the troubled unit attempts to repair the glitch at node level. By reconfiguring the firmware, the unit is effectively reconfiguring the circuit, bypassing the error. If it is unsuccessful, the unit’s buddies perform a back-up operation, reprogramming themselves to carry out the broken unit operations as well as their own. Unit-level intelligence is used in the first case, but should this fail, network-level intelligence is used. All the operations are performed automatically, there is no human intervention

This is some captivating research with far-reaching benefits. If computers could heal themselves at long-distance, millions of dollars would be saved. Also, the longevity of space missions may be extended. This research would also be valuable to future manned missions. Although the majority of computer issues can be fixed by astronauts, critical systems failures will occur; using a system such as SCARS could perform life-saving back up whilst the source of the problem is being found.

Source: UA News

Posted on by Fraser Cain

Pluto, Planet X

In the beginning of the 20th century, astronomers studied the orbit of Neptune and calculated that there must be another planet in the outer reaches of the Solar System that was pulling at the planet with its gravity. Percival Lowell, who was made famous by his “discovery” of canals on Mars, coined the term for this theoretical object: Planet X.

Lowell performed two searches for Planet X, but failed to turn up the object. He revised his predictions for the location of Planet X twice, and failed to find it. Ironically, two faint images had been recorded on photograph plates at the Lowell observatory, but Lowell didn’t recognize them.

Lowell’s observatory continued to search for Planet X up until his death in 1916. So the task fell to Clyde Tombaugh. Tombaugh’s job was to systematically observe pairs of photographs taken of the night sky. He used a machine called a blink comparator, which flashed two images of the same region of the sky. Any moving objects, like asteroids or undiscovered planets, would appear to change in position from one image to the next.

On February 18, 1930, Tombaugh finally turned up the object he was looking for, and announced that he had discovered Planet X, later renamed to Pluto.

Astronomers have been searching for additional planets beyond Pluto ever since, hoping to find the elusive Planet X. Japanese astronomers have predicted that an object between the size of Mars and Earth could be out at the end of the Kuiper Belt – a region known as the Kuiper Cliff, at 55 astronomical units from the Sun.

Posted on by Fraser Cain

Surface of Pluto

When you imagine cold, icy Pluto, orbiting in the distant regions of the Solar System, you imagine snowy white ball.

You can also look through these books from Amazon.com if you want more information about Pluto.

But images of Pluto, captured by the Hubble Space Telescope have shown that Pluto’s surface isn’t just pure ice. Instead, it has a dirty yellow color, with darker and brighter regions across its surface. Hubble studied the entire surface of Pluto as it rotated through a 6.4 day period.

The images revealed almost a dozen distinctive features never before seen by astronomers. This included a “ragged” northern polar cap cut in half by a dark strip, a bright spot seen to rotate around the dwarf planet, and a cluster of dark spots. The images also confirmed the presence of icy-bright polar cap features.

Some of the variations seen on Pluto’s surface could be topographic features, like basins and fresh impact craters. But most of them are probably caused by the complex distribution of frosts that move across Pluto’s surface during its orbital and seasonal cycles.

The surface area of Pluto is 1.795 x 107 square kilometers; about 0.033% the surface area of Earth.

When Pluto is furthest away from the Sun, gases like nitrogen, carbon monoxide and methane partially freeze onto its surface.

All will be revealed when NASA’s New Horizons spacecraft finally arrives at Pluto in 2015, finally capturing close-up pictures of Pluto and its moon Charon.

Posted on by Fraser Cain

Who Was Pluto Named After?

You’re thinking about a certain Disney dog, aren’t you? Goofy’s pet dog? Nope, it was actually named after Pluto, the Roman god of the underworld.

You can also look through these books from Amazon.com if you want more information about Pluto.

When Pluto was first discovered by Clyde Tombaugh in 1930, he was given the honor of giving it a name. Although they were calling it Planet X informally, they needed something that matched the rest of the planets in the Solar System.

The name Pluto was suggested by Venetia Burney, an 11-year old school girl in England. She was interested in ancient mythology, and thought that Hades, the Greek god of the underworld, made a good name. She suggested Pluto, to match the Roman god names given to the other planets.

Each astronomer in the Lowell Observatory was allowed to vote on a short list of names: Minerva, Cronus, and Pluto. Every one of them voted for Pluto. Venetia was given a 5-pound reward for providing the name.

In other languages, the name has been translated to names that match underworld god mythology, such as Yama, the Guardian of Hell in Buddhist mythology.

Posted on by Fraser Cain

Mass of Pluto

In everything but the largest telescopes, Pluto appears as a tiny dot. And determining mass from so little information is incredibly hard to do.

Astronomers could only try and work out its mass by knowing how bright it was – its albedo. They could detect that it had large quantities of methane ice on its surface, and so astronomers knew that it had to be very bright. But there were sure about Pluto’s size, or even if it was larger than Mercury or Earth’s moon.

But astronomers lucked out in 1978 when James Christy discovered Pluto’s moon Charon. Once you get a system where two objects are orbiting one another, such as in the case of Pluto and Charon, you can use Newton’s formulation of Kepler’s Law to work out the mass very precisely.

Plugging in the orbital information for Pluto and its moon Charon, astronomers calculated its mass to be 1.31 x 1022 kg – less than 0.24% the mass of Earth. Followup observations were able to determine its size very accurately as 2,390 km across.You can also look through these books from Amazon.com if you want more information about Pluto.

Posted on by Fraser Cain

Temperature of Pluto

Pluto's temperature makes it one of the coldest places in the Solar System.

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With such a large distance from the Sun, Pluto is incredibly cold. But this temperature can vary enough to change the dwarf planet significantly. At its closest point, it warms up enough so that Pluto’s nitrogen atmosphere sublimates and forms a diffuse cloud around it. As Pluto gets further away from the Sun; however its this atmosphere freezes out, and falls to the surface of Pluto like snow.

First, let’s define some measurements. Room temperature is considered 21-degrees Celsius or 70-degrees Fahrenheit. The freezing point of water is 0-degrees Celsius or 32-degrees Fahrenheit. But when you’re measuring temperatures on Pluto, you really want to use Kelvin.

Zero Kelvin is the absolute zero temperature; a theoretical maximum point where no more energy can be extracted from a system. 0-degrees Kelvin corresponds to -273-degrees Celsius.

The surface of Pluto, in comparison, can range from a low temperature of 33 Kelvin (-240 degrees Celsius or -400 degrees Fahrenheit) and 55 Kelvin (-218 degrees Celsius or -360 degrees Fahrenheit). The average surface temperature on Pluto is 44 Kelvin (-229 Celsius or -380 Fahrenheit).

Back in the days when Pluto was still a planet, it was the coldest planet in the Solar System. But now it’s just a regular temperature dwarf plant – poor Pluto. Neptune is now the coldest planet.

Posted on by Fraser Cain

Distance to Pluto

Pluto has the most elliptical orbit of all the planets and dwarf planets. In addition to this widely varying orbital distance, Pluto is also highly inclined, orbiting above and below the planet of the ecliptic that the rest of the planets follow.

You can also look through these books from Amazon.com if you want more information about Pluto.

Pluto Distance from the Sun
Since Pluto orbits the Sun, like the rest of the planets and dwarf planets, astronomers typically measure the distance of Pluto in terms of Astronomical Units (AU). 1 AU measures the distance of the Earth to the Sun.

At its closest point, Pluto is only 29 astronomical units from the Sun (4.4 billion km or 2.75 billion miles). And at its most distant, it can be 49 AU (7.29 billion km, or 4.53 billion miles) from the Sun. In addition to being highly elliptical however, Pluto’s orbit is also inclined at an angle of over 17-degrees. At some points along its orbit, Pluto is above the plane of the ecliptic that the planets follow, and at other times, it’s below.

Pluto’s average distance from the Sun is 40 astronomical units (5.91 billion km or 3.67 billion miles).

Distance From Earth to Pluto
The Earth is only 1 AU from the Sun. When the Earth and Pluto are perfectly lined up with the Sun, their closest point is approximately 28 astronomical units. And at their furthest point, when Earth is on the opposite side of the Sun, Pluto can be 50 astronomical units.