Universe Today

July 16, 2007December 26, 2015 by Fraser Cain

Building an Engine that Can Throttle Down

Here on Earth, we’ve gotten used to the concept of a car’s accelerator pedal. Put it down a little, and the car accelerates slowly. Put the “pedal to the metal” and you’ll go faster. Imagine trying to park your car when you only have two choices: off and full speed. Developing a similar concept for a rocket is very difficult. Most rockets are designed to go at full blast, or nothing at all.

A variable acceleration rocket would tremendously useful for landing on the Moon. Instead of firing the landing rockets in short bursts, astronauts could throttle down for a nice smooth landing. But building an engine like this is harder than it sounds.

NASA researchers think they’ve got a prototype engine that should give the variable rate of acceleration astronauts are looking for. The newly developed Common Extensible Cryogenic Engine (CECE) is a variant on the RL10 engine that boosted the Surveyor robot landers to the Moon back in 1966-68. The RL10 is designed to only go full throttle, so adding the variable thrust was difficult.

The main problem is that changing the throttle affects how the whole engine functions. At low power, liquid hydrogen can slow and vapourize in the coolant lines. This might cause the engine to stall. During one test, the experimenters discovered that the engine “chugged”, vibrating 100 times a second. It turned out oxygen vapours were forming on the injector plate, inhibiting normal flow, causing the vibrations.

It’s not ready for space yet, but CECE might eventually become part of the design of a future lunar lander. The astronauts returning to the Moon will be very appreciative.

Original Source:Science@NASA

July 16, 2007December 26, 2015 by Fraser Cain

Astrosphere for July 16, 2007

Another day, another astrosphere.

First, the picture. Here’s another image of comet CV2006VZ13 taken by forum member RickJ. I hope you’re enjoying the comet pictures. With 2006VZ13 making its way across the night sky, we’ll get a chance to see more of it. Keep snapping!

Earth and Sky is reporting on a successful method for determining the age of stars in other galaxies.

Livescience has a skeptical look at new research that pet visits to the emergency room increase during full moons.

On Belt of Venus, you can see the difficult challenge of splitting Alpha Scorpii (Antares / GNT 1) in a telescope.

The London Free Press has the results from a survey that shows how Canadians are anticipating space tourism.

July 16, 2007December 26, 2015 by Fraser Cain

Sleek Spacesuit Designed

Current spacesuit designs are bulky and cumbersome to wear. That’s because they put an entire atmosphere around the astronaut, keeping them safe from the vacuum and temperature extremes of space. Instead of encasing an astronaut in a complete atmosphere, an alternative design using mechanical counter-pressure could give astronauts greater flexibility working in the vacuum of space.

Dava Newman, a professor of aeronautics and astronautics and engineering systems at MIT has designed a new spacesuit prototype that looks more like a superhero costume than a bulky NASA spacesuit. It works through the process of mechanical counter-pressure. Instead of an atmosphere to put pressure on the outside of a human body, it uses tight layers of fabric to give skin the pressure it needs.

Current spacesuit designs can weigh up to 136 kg (300 pounds), and are so restrictive to movement, that astronauts will spend the majority of their energy just working against the suit to bend it. A fabric-based design would be much more flexible and give astronauts a freedom of movement. Another advantage is safety. Even the slightest tear on a spacesuit will compromise its atmosphere, while a fabric suit can be easily patched up. To deal with the temperature extremes, astronauts could just put on and take off specially designed clothing.

The challenge in building a fabric-based spacesuit is to come up with a design that can exert close to one-third the pressure exerted by Earth’s atmosphere. This is 30 KPa (kilopascals). The current prototype suit only provides 20 KPa consistently, but new models have gotten up to 25 to 30 Kpa. The best solution might end up being a hybrid, with the head and torso covered with a traditional spacesuit, and the arms and legs covered only in fabric.

Original Source: MIT News Release

July 13, 2007December 26, 2015 by Fraser Cain

Podcast: Listener Survey

It’s time to answer questions again, but this time we hope that you’ll take a minute and answer ours. We’ve written a brief survey that we hope you’ll take a minute to fill out. This survey will allow us to collect some general demographic information about our audience so we can make the show even better. We promise it doesn’t even ask your email address – and, if you fill it out, we’ll give you a link to a special, full-length episode that does not appear on our feed.

Click here to take the survey.

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Listener Survey – Show notes and transcript

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July 13, 2007December 26, 2015 by Fraser Cain

Supernova Theory Strengthened by New Observation

Type Ia supernovae are used as cosmic yardsticks to measure distances in the Universe. That’s because they always explode with roughly the same intensity. The theory goes: Type Ia supernovae occur when a white dwarf star consumes a specific amount of material from a binary partner. It can’t hold the extra mass, and so it explodes.

Now observations by the European Southern Observatory’s Very Large Telescope have turned up evidence of this stream of material in the region around a recently exploded Type Ia supernova, lending evidence to this theory.

The supernova is SN 2006X, which exploded 70 million light-years away in the spiral galaxy M100. The ESO observations turned up traces of material that would have been around before the explosion. This material was arranged in shells around the central explosion. Since the explosion is expanding out at a rate of 50 km/s, astronomers believe the material was ejected about 50 years before the explosion.

This 50 km/s velocity of material is important, because it matches speed of stellar wind pumped out by red giant stars. As the expanding sphere of supernova wreckage crashes into this material from the red giant, it gets absorbed in a way that astronomers can distinguish.

Original Source:ESO News Release

July 13, 2007December 26, 2015 by Fraser Cain

Astrosphere for July 13, 2007

So much news, so little time. Here’s what’s new and cool around the astrosphere today.

First the photo. This is the Eagle nebula taken by forum member seeker372011

Next, if you haven’t seen already, we’ve got a cool new logo on the Bad Astronomy/Universe Today forum. Visit this link, check it out. You can even see some alternate designs that were developed. Thanks to Doctor Know for all his help.

Astroprof is working his way through the 7 wonders of space exploration. Here’s Mariner 2.

Scientific American has an interesting story on how smog might create beautiful sunsets. But that depends on the colour you like.

Popular Mechanics talks about how the private rocketeers got real.

Derek Breit from the International Occultation Timing Association wanted me to inform everyone that they’ll be having their annual meeting on July 20-21 in Pasco, Washington.

July 12, 2007December 26, 2015 by Fraser Cain

If There’s Oxygen, There’s Life

If aliens visited our Solar System, it would only take them a moment to figure out which planet is the one with all the life on it. That’s because our atmosphere has a high percentage of oxygen in its atmosphere. The presence of oxygen in our atmosphere has given scientists the key to searching for life on other worlds. But what if there are purely natural processes, that could confuse the search for life, fooling powerful new space observatories like the Terrestrial Planet Finder and Darwin.

Don’t worry. A new simulation by a team of US researchers shows that no natural process on a habitable world with liquid water could keep high levels of oxygen and ozone present in an alien atmosphere. If there’s oxygen, there’s life.

Most of the oxygen (O2) in the Earth’s atmosphere was thought to have been generated though photosynthesis. Plants use energy from the Sun, taking in carbon dioxide and releasing O2 as a byproduct. Over time, this oxygen has built up in our atmosphere to its current ratio of 21%, with the rest nitrogen and other trace gases.

This ratio is very important to the search for life in the Universe. Over the next few decades, a fleet of spacecraft and experiments are being built that will be so sensitive, they’ll be able to analyze the atmosphere of a distant Earth-sized world. Find oxygen or ozone in that planet’s atmosphere – so goes the thinking – and you’ve found a world with life. Like our own planet, some organic process is refreshing the oxygen in the atmosphere, stopping it from reacting away.

One recently canceled spacecraft is the Terrestrial Planet Finder, which would be sensitive enough to analyze the chemical constituents of a distant atmosphere. Sadly, this mission was scrapped after budgets were transfered to support the Vision for Space Exploration, which will send humans back to the Moon, and on to Mars. Don’t worry, though, the Europeans are working on the problem too with their Darwin mission. And it hasn’t been canceled… yet.

These missions (if they do get launched) will be able to spot oxygen and ozone in a distant world’s atmosphere. But could they be fooled? Are there natural processes that could generate similar levels of oxygen and ozone? If so, then it would make the search for life extremely difficult, generating false positives that would confuse scientists.

There have been a few scenarios that scientists think might create false positives for life. For example, in a runaway greenhouse planet like Venus, large amounts of hydrogen could be escaping from a hot, moist atmosphere. Since this hydrogen is originating from water (H2O), this would leave oxygen behind. If an extrasolar planet was losing its ocean to space, it might fool the detectors.

In another situation, a frozen, Mars-like planet could be large enough to retain heavy gases, but too small to maintain volcanic outgassing. The frozen surface would then inhibit the loss of oxygen, but also not consume it.

The trick to both of these scenarios, though, is that they would exist on planets outside a star’s habitable zone. Careful observers would be able to rule them out ahead of time.

A team of US researchers has developed a simulation to see if there are scenarios that could generate false positives, and they weren’t able to find anything that would fool future telescopes. The research paper is titled Abiotic Formation of O2 and O3 in High-CO2 Terrestrial Atmospheres, and it was recently accepted into the journal Astronomy & Astrophysics.

They ran many simulations, factoring in all the potential variables that would simulate an Earthlike world, including different rates of volcanic outgassing and ultraviolet radiation.

They weren’t able to come up with any scenarios in which a habitable planet with liquid water could generate a false positive result for O2 or O3 that would fool a telescope like the Terrestrial Planet Finder or Darwin.

Original Source: Arxiv research paper

July 12, 2007December 26, 2015 by Mark Mortimer

Project Mercury and Project Gemini

Project Mercury and Project Gemini preceded the landing of a person on the Moon. These projects taught the United States how to safely fly humans in to space and out to adventure. Steve Whitfield has prepared a Pocket Space Guide for each of these. Within, he combines smooth narrative with hundreds of both colour as well as black and white pictures to bring a reader complete, colourful little synopses. Their result is a generous reminder of what people can achieve when given a task, no matter how hard.

Both Project Mercury and Project Gemini were extreme engineering marvels as much as Project Apollo. The first placed people above Earth’s atmosphere and into space. The second gave control to the pilots of the space craft in order to give them independence and capability with which to complete missions. The third, as most remember, put men upon the lunar surface. Given the definitive goals for each project, definitive results must occur. This hard definition lends well to ready documentation. In consequence, Whitfield can draw on clear objectives and well documented achievements for his pair of books. He does this for a remarkably fine result.

The Project Mercury guide clearly shows the veritable flying phone booth that was the first vehicle the United States used to put men into space. Yet Whitfield doesn’t begin there, as the project started well before the Mercury capsule was lofted. First he mentions the unmanned launches of Little Joe and Big Joe. As well, there’s a bit on Ham the chimpanzee doing tests, and numerous unoccupied vehicles doing systems tests. Then, after providing a short one paragraph description of each of the 20 preliminary tests within the Mercury project, Whitfield provides a few pages for each of the seven manned launches. Given the allowances in these compact guides, they only provide the barest of technical information and not much else. Therefore, Whitfield gives statistics regarding the space craft and launch vehicle. After, he lists some of the more exciting moments of the flight as well as noting the objectives achieved. These clearly show the increasing confidence and capability of all the people involved in the space program of the United States.

Closing the book, though in reality consisting of about half the pages of the book, Whitfield provides copious colour photographs. These act as wonderful memories of an exciting project, whether they be pictures of the contents of the astronauts’ survival package or a sequence of an astronaut while in orbit. Perhaps most fitting is the final picture of the women who trained in parallel with the men in the hopes that they too could go into space.

The outline of the Project Gemini pocket space guide follows that of the Project Mercury guide. However, this project had no unmanned trials, but only a few Agena targeting craft. Hence, this guide focuses solely upon the 12 manned Gemini flights. Again, each of the twelve has a few pages to describe the flight. Where applicable, these include; objectives, the launch, any highlights, and the landing. Concluding the text section is an overview of an interesting plan to use the Gemini craft and launcher to put a man upon the Moon. Of course, this ended up not being necessary, but is a rewarding tidbit nonetheless.

The photograph section in the Project Gemini guide is as varied and plentiful as for the Mercury guide. Each crew and their badge get an entry. There’s Ed White doing the first space walk for the United States. An angry alligator and an Agena silhouetted against the Earth’s far away surface or other visual testaments. These and others showcase events of the Gemini project vividly and clearly.

Both these guides are great examples of well edited and very detailed works. Given their subject manner, it’s easy to get carried away, but they don’t do so. These guides summarize the achievements and provide rewarding visual testaments without overweighting the reader with managerial nuances or technical trivia. Certainly, there’s a dearth of substance but such is not the intention of a guide. The consequence is that these books practicably do justice but not to excess. Anyone wanting an introduction to human space flight or an overview of multi-year project development will benefit from reading either or both of these two. As well, they’re handy references for anyone not wanting to memorize.

Only a few days were needed to transport a human to the Moon. But, more than a decade of research and discovery were necessary to bring all the abilities together to make this happen. Steve Whitfield provides two guides; Project Mercury and Project Gemini that display two projects that preceded Apollo. Their clarity happily bring these heady times back to the ready fingertips of any reader.

July 12, 2007December 26, 2015 by Fraser Cain

Scientists are Keeping an Eye on a Martian Dust Storm

From time to time, dust storms get going on Mars that can severely limit our view of the Red Planet, and the ability of the Mars Rovers to generate power. There’s a storm on Mars right now that NASA scientists are watching carefully to see how it affects the fleet of spacecraft on and around the Red Planet.

This latest storm got rolling during the last week in June in the planet’s cratered southern highlands. Over the course of a week, it grew large enough to encircle the entire planet. And now dust is drifting up into the northern hemisphere as well. As the winds sweep dust into the atmosphere, it gets warmer, adding to the storm’s power and helping it to pick up more dust.

When the dust gets thick enough, it reflects sunlight away from the surface. This cools the storm and causes it to settle down.

For the NASA spacecraft currently at Mars, this current storm is stealing some of their power. Fortunately, it’s currently summer for the Mars rovers, so they’re experiencing this dimming during the peak of their energy generation.

The storm will likely last a few months more, and then the atmosphere will clear up again.

Original Source:ASU News Release

July 12, 2007December 26, 2015 by Fraser Cain

Water Vapour Discovered in an Extrasolar Planet

Scientists have reported the first conclusive evidence of water vapour in the atmosphere of an extrasolar planet. Before we load up the spaceships to search for life, however, consider the fact that this planet, HD 189733b, is larger than Jupiter, and orbits its parent star in just 2.2 days. That’s hot hot water.

The discovery was made using the mighty Spitzer space telescope. The astronomers pointed Spitzer at the parent star, and measured the chemical consistency of its light as the planet passed in front – aka, transited. As the starlight dimmed – blocked by the planet – the chemical constituents of the star changed to show a distinctive pattern. Astronomers know that only water can absorb these specific wavelengths of infrared radiation.

As I mentioned above, this planet is certainly a “hot Jupiter”. It contains 1.15 the mass of Jupiter (and 1.25 the diameter), but it orbits its parent star at a distance of only 4.5 million km. In comparison, our own Mercury is a distant 70 million km from the Sun.

It’s close, so it’s hot. Its atmospheric temperature is about 1000 Kelvin (more than 700 C). With this heat, all the water vapour in its atmosphere can’t condense, rain or form clouds.

It’s also tidally locked to its parent star, only showing one face to the star at all times (like the Moon and the Earth). This constant facing probably generates fierce winds that sweep around the planet from the day side to the night side.

Like I said, not the best place to find life, but still, an amazing discovery.

Original Source:ESA News Release