Universe Today

April 28, 2008December 24, 2015 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.

April 27, 2008December 24, 2015 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

April 27, 2008December 24, 2015 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.

April 26, 2008December 24, 2015 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.

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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.

April 26, 2008December 24, 2015 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.

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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.

April 26, 2008December 24, 2015 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.

April 26, 2008February 6, 2017 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.

April 26, 2008December 24, 2015 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.

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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.

April 25, 2008December 24, 2015 by Ian O'Neill

ATV Jules Verne Boosts Space Station to Higher Orbit (Video)

For the first time since docking with the International Space Station (ISS) on April 3rd, the Automated Transfer Vehicle (A T V) “Jules Verne” has been awoken and instructed to carry out an impressive task: push the ISS to a higher orbit. The robotic supply vessel, currently attached to the station’s Zvezda module carried out a 12 minute 20 second burn of its main engines. This is the first time an ESA spaceship has carried out such a task and it appears to have performed flawlessly, lifting the 280 tonne station 4.5 km (2.8 miles) to a new altitude of 342 km (213 miles). In true ESA style, they’ve even released a cool video simulation of the event…

Periodically, the ISS needs a small push in the right direction. As the station orbits Earth, it experiences a small amount of friction from the extended atmosphere of our planet. This atmospheric drag slows the orbiting outpost, making it drop to a lower orbit. When needed, the ISS must to be pushed to higher altitudes. Until now, “re-boosts” have been performed by the Space Shuttle, Russian Progress and by the ISS itself; but today, it was the turn of the most advanced European spacecraft ever put into space. Due to the large quantities of fuel still on board, Jules Verne is ideal for this manoeuvre.

At 04:22 GMT Friday morning, two of the four powerful ATV rockets burst to life after being given the signal from mission control in Toulouse, France. The supply ship provided a thrust of 2.65 m/s, accelerating the ISS along its orbital path. This increased speed increased its orbit. Mission controllers carefully monitored events for the long 740 seconds.

See the ESA video simulation of the ATV re-boost »

This re-boost comes after three weeks of inactivity for the ATV. The unmanned cargo vessel was launched on March 9th to take 1150 kg (2535 lb) of water, food and other supplies to the ISS. This proved to be a very busy time for space traffic control. First the ATV was launched, then on March 11th Space Shuttle Endeavour was sent on her way, then on April 8th Soyuz ISS 16S was launched. Jules Verne drew the short straw and had to wait in a parking orbit until Endeavour had docked, carried out its mission and then returned home. The ATV used this time to run tests until it was cleared for docking on April 3rd.

Now the ISS is ready for the arrival of Space Shuttle Discovery (STS-124) scheduled for launch at the end of May. Discovery will deliver the Japanese Kibo laboratory to be installed on the growing station. Another three re-boosts are planned for the ATV on June 12th, July 8th and August 6th. Shortly after the last boost, Jules Verne is destined to be detached from the Zvezda module and dropped into the atmosphere, carrying 6.5 tonnes of trash into a controlled re-entry burn over the Pacific Ocean. A sad end to an amazing piece of technology.

Source: ESA

April 25, 2008December 24, 2015 by Ian O'Neill

Space Golf and Other Zero-G Sports on the ISS

Cosmonaut Sergei Krikalev practices his swing on the station in 2005 (Element 21 Golf Company)

Humans and sports go hand-in-hand; it was only a matter of time before sports pushed into space. Whether astronauts are practicing their cosmic golf swing, throwing boomerangs (for science of course!), hurling footballs or creating their own unique zero g activity, we will see some new and inventive space sports in the future…

Launched on board Apollo 14 in February 9th, 1971, astronaut Alan Shepard had brought a little extra weight with him. A golf club and golf balls. He wanted to be the first to play golf on the dusty surface of the Moon. His dream became a reality, doing a one-handed drive, blasting the ball over 200 yards during one of his Moon walks. Not bad considering how restrictive his space suit must have been (although the 1/6 Earth gravity will have helped the ball along a little). Shepard held the extra-terrestrial golf drive record for 35 years until cosmonaut Mikhail Tyurin shattered the record with a million-mile hit from the International Space Station in 2006 (it was actually a miss-hit, but mission scientists think it orbited the Earth for 2-3 days before falling into the ultimate hazard… the Earth’s atmosphere).

In fact, the International Space Station astronauts have tried out a variety of sports. An average ISS astronaut’s day consists of six and a half hours of work, two hours for exercise and about eight and a half hours for sleep. Naturally, as we do on Earth, the orbiting men and women have some time to fill with personal activities, including sport. A lot of the time, the odd dabble with a boomerang and a session on the treadmill has a scientific merit, but some of the sporting activities were done simply for fun. In the case of Tyurin, sport may also be a marketing stunt (the ISS golf driving range was set up by Canadian golf club manufacturer Element 21) – but I’m sure he had a special sense of satisfaction teeing off the high altitude location.

Zero-G offers many options for new sports too. In a televised interview last week, NASA astronaut Garrett Reisman (who is currently residing on the station as the Expedition 17 flight engineer) admitted to finding the mundane task of filling up large water bags rather enjoyable:

“We started tossing them kind of like a medicine ball, and we realized that you could toss and catch and then go for a ride on this big thing as it takes you away. So there’s all kinds of possibilities, and if there’s any good ideas out there, let me know. We’ll try it.” – Reisman.

Whilst this may not constitute a “sport”, it could be a fun game. When the Expedition 16 and 17 crews overlapped, there were six crewmembers to participate in the orbital fun. Record breaker Peggy Whitson commented on a relay race that the crew had through three of the station modules. “We raced from one end of a module, relayed with the person waiting at the other end three modules away, and then sprinted back and sent a third person,” Whitson said. “So it was pretty fun.” Apparently her team (including Reisman) won.

Although the ISS astronauts may not have many sporting options at their disposal, mission control makes sure they don’t get bored. They have a treadmill and stationary bike, and they’ve played weightless basketball, Frisbee and thrown boomerangs. Plus the odd round of golf it seems. Even throwing away the garbage seems like a superb way to pass the time. Have a look at this NASA video of the station crew having way too much fun in orbit (I do admit, I am very jealous!).

All these activities are going on in the space station not exactly built for sporting activities. With the advent of space tourism, it’s not hard to envisage the development of space sports, perhaps in orbital space hotels with large volumes of space available for sports activities. One such sport could be the possibility of zero-G dodgeball (pictured). This was already attempted on board Boeing 727-200 jets operated by the Zero Gravity Corp. (Las Vegas). Although periods of weightlessness would have been short, it must have been fun.

Original source: Space.com