Communicating with Mars

In a landmark discovery this week, NASA's Phoenix lander dug a trench in the Martian soil and watched as small chunks of water ice slowly evaporated. Scientists have known about the existence of water ice in the polar cap of Mars for a long time, but it was only in 2002 that the Odyssey spacecraft found evidence of much more ice just below the surface. This is what motivated the experiment on Phoenix that directly confirmed this vast reservoir of frozen sub-surface water. It's not easy to control an experiment from a hundred million miles away. Have you ever wondered how NASA actually does it?

Even when the Earth and Mars are as close as they can come to each other in their orbits they are separated by more than 30 million miles, and sometimes they are nearly 250 million miles apart. How do we communicate across such enormous distances? It's similar to how we do it on Earth: we encode our signals into radio waves and send them from one antenna to another. Radio waves travel at the speed of light, more than 186000 miles or eight times around the Earth in a single second. This is very practical for communicating across the planet, but it's fairly slow to communicate between planets. When it is closest, a radio signal to the Mars lander takes several minutes to get there -- and its response takes several minutes to return to Earth. More typically, the trip takes 10 minutes each way. Imagine playing a video game where any move you make with the controller doesn't show up on the screen for 20 minutes!

With such slow communication, scientists do not control the Phoenix lander the same way you might play a video game. Many of the functions of the experiment need to be automated and programmed ahead of time. So they simply tell the lander to "dig a trench" then "take a picture" and wait for the image to be sent back. This led to the discovery earlier this week of some "white stuff" beneath the soil. To test whether it might be water ice they waited for a day, asked the lander to take another picture, and compared the second picture to the first one. This showed that some of the crumbs from the digging actually disappeared in the second picture -- suggesting that they were made from ice and had evaporated.

If you think playing a video game with a 20 minute lag time might be frustrating, imagine what it would be like with people on both ends of the line. This is one of the many challenges of sending astronauts to Mars, but it's something that most people don't think about.

WorldWide Worthless

This morning I received an email from my mother-in-law with the subject line: "Travel to the Stars!' Naturally, I was intrigued. She wanted to know whether I had heard about the new free program from Microsoft called WorldWide Telescope, just released yesterday. I had actually seen some of the headlines and my impression was: oh, Microsoft is trying to compete with Google Sky, which came out last August. But to be fair, I decided to download the new software and try it out.

My first complaint is that WorldWide Telescope only runs under Windows (surprise!). Google Sky also runs on Mac and Linux machines. I decided to install it on a laptop I use for presentations, where I had successfully installed Google Sky several months ago. I went to the website at WorldWideTelescope.org, which looked very nice, and downloaded the 20 MB install application. No problem. When I ran this application, it downloaded an additional 90 MB of Microsoft software that WorldWide Telescope depends on. Everything seemed to install just fine, so I clicked the new shortcut that had been placed on my desktop. The program loaded and a dialog box appeared with instructions about what to do with my mouse to control the interface. Looks a lot like Google Sky. So I started to pan around the sky -- and within a few seconds the program crashed. I rebooted the machine for a fresh start, launched the program and tried to pan again -- another crash. And a third. And a fourth.

At this point, I decided to uninstall the software and everything that came with it. I also decided to check that my copy of Google Sky was still working -- and thankfully, it was. In the process I also discovered that Google now has a version of Sky that runs in the maps interface through a web browser. If you go to the WorldWide Telescope website you can watch flash movies of children's reactions as they explore the sky through the software. Microsoft is great at public relations, but not so great at writing software that actually works. As for me, I'm sticking with Google Sky.

Ozone and Climate

Many people confuse the issue of climate change (or global warming) with the other major influence of humanity on the Earth's atmosphere: the hole in the ozone layer. These phenomena are actually caused by two very different aspects of atmospheric chemistry, and they have distinct consequences for the environment. But this week, climate scientists announced a surprising connection between the ozone layer and climate change: if we adopt one approach to cooling the planet, it could make the ozone problem worse.

Ozone is just another form of oxygen. The oxygen that we breath is really a molecule consisting of two oxygen atoms bound together. Ozone is similar, but it has three oxygen atoms. High in the Earth's atmosphere there is a relatively thin layer of ozone, and because of its specific structure it acts like sunblock -- filtering out much of the harmful ultraviolet radiation coming from the Sun before it ever reaches the ground. Back in the 1980's, scientists discovered that large holes were developing in the ozone layer, particularly over the polar regions of the planet. Further study linked this depletion to widespread use of chlorofluorocarbons (CFCs), particularly as refrigerants and as propellants in spray cans for consumer products. Alternative gases were quickly identified for these uses, and CFCs were phased out in most industrialized countries. The results were dramatic -- further monitoring of the ozone holes showed them begin to recover as the widespread use of CFCs was discontinued. It was a landmark achievement for climate science and its influence on public policy.

More recently it has become clear that the global climate is getting warmer and that, like ozone depletion, a substantial fraction of the effect can be attributed to human activities. In this case the underlying cause is the release of so-called greenhouse gases -- molecules like carbon dioxide (CO2) and methane (CH4) that trap the Sun's infrared radiation or heat from being released back into outer space. Large volumes of these gases are produced from burning fossil fuels like coal in power plants or gasoline in automobiles -- and as humanity releases more greenhouse gases than the environment can naturally absorb, it builds up in the atmosphere, traps more heat, and gradually warms the planet. This has been happening dramatically since the industrial revolution in the late 1800's, and unless we find suitable alternatives for our energy needs we risk a major disruption of our climate system later in this century.

Since this is a much bigger problem than finding substitute refrigerants and propellants -- and because the consequences are potentially much more severe -- some climate scientists are considering how to cool the planet without reducing greenhouse gas emissions. In the long term climate record that has been reconstructed from ice cores drilled in Antarctica, scientists noticed that historical periods of global cooling often follow major volcanic eruptions. The cooling was traced to large quantities of sulfates that were hurled into the Earth's upper atmosphere during the eruptions. The sulfates block some of the incoming sunlight from ever reaching the surface, which can counteract the warming effects of increased greenhouse gas concentrations (though other problems like ocean acidification still remain). So if global warming gets really out of control, the scientists reasoned that we could manually inject sulfates into the upper atmosphere like an artificial volcanic eruption to cool the planet.

Working from this premise, the study released this week examined the other possible consequences of engineering the climate with massive injections of sulfates -- and this is where ozone returns to the picture. It turns out that sulfates also deplete the ozone layer, and if enough of them were injected into the upper atmosphere to offset the expected warming in the coming decades it would destroy between 1/4 and 3/4 of the Arctic ozone layer and delay the expected recovery of the ozone hole over the Antarctic by between 30 and 70 years. So if we want a reasonable climate and an ozone layer, sulfates might not be the best answer.

Personal Space Telescope

The beautiful images produced by the Hubble Space Telescope have probably done more to capture the public imagination than any other NASA project since the Apollo moon missions. As you might expect, not just anyone can use Hubble. The allocation of observing time is extremely competitive, and even most professional astronomers have never used it. Few people realize that Canada also has a space telescope -- and now, a team of Canadian astronomers wants to help any Canadian citizen use it for their own projects.

In June 2003, Canada launched its first space telescope called "MOST" for Microvariability & Oscillations of STars (or Microvariabilité & Oscillations STellaires for those in Quebec). It's quite a bit smaller than Hubble, roughly the size of a large suitcase, earning it the nickname "Humble Space Telescope". Because of its modest size, MOST was lifted into orbit on a decommissioned nuclear missile from Russia. Under an international peace treaty the missile was required to be destroyed anyway -- so they decided to use it for science! Inside MOST there is a 6-inch diameter reflecting telescope and a high quality digital camera. Scientists use the camera to take a series of images of pulsating stars, and record the amount of light emitted by the stars over time. They use this information to learn about the insides of the stars -- a cutting-edge technique known as asteroseismology.

After four years of very successful science operations, MOST had reached the end of its expected life, but it was still running. Rather than keeping the telescope for themselves, the MOST science team decided to do something unprecedented: they announced that any Canadian citizen could submit a proposal to use it. Young, old, scientist, amateur -- it didn't matter. The process was open to all. They called this new phase of the project "MOST: My Own Space Telescope". No word yet on whether any citizen projects have been selected, or announcements of their results. But the concept certainly reflects the best of the Canadian spirit.

Lunar Eclipse Demystified

Tomorrow night the Moon will once again plunge into the shadow of the Earth, marking the third lunar eclipse in the past 12 months. Despite the recent frequency of such events, your next chance to see a total lunar eclipse won't come for nearly three years, in December 2010. While not as spectacular (or rare) as a solar eclipse, watching the Moon turn dark red (but not invisible) has its own rewards. And this time, it will be joined by Saturn and the bright star Regulus -- both within a few degrees on the sky.

People often wonder why lunar eclipses are so much more common than solar eclipses, and why the Moon doesn't pass through the shadow of the Earth every month. Since both events involve the alignment of the Sun, Earth, and Moon it seems like they would both occur with similar frequency. But the dark shadow of the Earth (the umbra) is roughly three times the diameter of the full Moon, so the alignment doesn't have to be perfect as with a solar eclipse -- where the Sun and Moon appear almost the same size in the sky. This also makes lunar eclipses last much longer (about an hour, compared to just a few minutes) and allows half of the planet to see them each time (since you just need to be on the night side of the planet when they happen, not a special location where the alignment is perfect). Despite these advantages, the Moon doesn't pass through the Earth's shadow every month because its orbit is actually inclined by 11 degrees relative to the plane of the Earth's orbit around the Sun. So we only see a lunar eclipse when the full Moon occurs near the intersection of these two orbital planes (the so-called "line of nodes").

One of the interesting features of a lunar eclipse is that the Moon doesn't go completely black. Instead, it usually turns some shade of red when it passes through the darkest part of the Earth's shadow. We know that the Moon normally just reflects the light of the Sun -- so where does this red light come from? During a lunar eclipse, the light that reaches the Moon is just sunlight that has been diverted towards the Moon through the Earth's atmosphere. Why is it red? The answer turns out to be the same as "why is the sky blue?". The molecules in the Earth's atmosphere are similar in size to the wavelength of blue light, so they interact and scatter the blue light (making the sky blue) while letting most of the red light through (making the Moon look red). This is also why sunsets often look red.

If you've never seen Saturn through a telescope, this event will offer a good chance, since the ringed planet will appear within a few degrees (5 or 6 Moon diameters) of the lunar eclipse. The bright blue star Regulus (in the constellation Leo) will also appear nearby -- but it should be easy to distinguish from yellowish Saturn. Viewed with high power binoculars or a small telescope, the rings of Saturn are fairly easy to see, even for a pea-sized image.

Mars Asteroid Uncertainty

Earlier today, an asteroid as wide as a football field cruised past Mars at a distance just over three times the diameter of the red planet. By cosmic standards, this was a very near miss. The asteroid was discovered in late November, and in mid-December astronomers placed the odds of an impact at 1-in-75. Additional observations just before the new year increased these odds to nearly 1-in-25, but within two weeks the probability of an impact sank dramatically to just 1-in-10,000. All of the attention given to the developing story led a satire website to release an article headlined: "NASA plans to blow up Mars if asteroid misses".

With such wildly oscillating predictions, it would be easy to imagine that scientists simply don't know what they're doing. But predicting the path of an asteroid in space is a little like predicting the path of a hurricane over the ocean -- natural uncertainties in the observations that are used for the calculations lead to a range of possible positions as we predict further into the future. In the case of an asteroid, astronomers use the observed positions of the space rock over time to define an orbit from Kepler's laws. With positions observed over a reasonable fraction of the asteroid's path around the Sun, the orbit can be calculated very accurately. But with data spanning only a few weeks, the orbit is harder to define and each new observation can lead to significant changes when estimating the future path of the asteroid.

This is exactly what happened in the case of the Martian asteroid, officially named "2007WD5". While routine calculations of asteroid trajectories typically lead to one-in-a-million odds for any planet impacts, the early observations of 2007WD5 gave a better than 1% chance of striking Mars. This got the attention of many astronomers, and new observations came pouring in from around the globe, leading to a better estimate of the orbit and a new calculation of the impact probability, by then up to 4%. This led to even more excitement, and many new observations -- defining the orbit so well that an impact was effectively ruled out.

As cool as it would have been to watch a big rock punch a fresh crater into Mars, we should be comforted by the fact that astronomers are conducting their census of the asteroid belt. After all, the next near miss could belong to the Earth...

Reflecting on StarStuff

It's now been more than a year since I started this blog. I've had a great time with it, and I hope that I've been able to entertain and inform a few people along the way. A few months after I started, I began tracking visits using Google Analytics to help me get some sense of my audience -- and I discovered that I didn't have much of an audience. Even so, I decided to continue posting for at least a year.

I'm glad I did. If I hadn't continued, I would have missed the one remarkable event in the first year of this blog. On August 22, newspapers around the world carried an announcement by Google that the latest version of its popular "Earth" application also included the Sky -- turning any computer into a virtual telescope. One of my early posts to this blog speculated that such a feature might be coming soon, and during the final week of August that post attracted hundreds of users who were looking for the new software. In fact, about half of the visitors to this blog over the last 9 months came during those few days. Most didn't stay long. They were looking for something else.

Aside from that week in August, Google Analytics tells me that during a typical week about 15 unique visitors view this blog. Roughly 80 percent are new visitors, meaning that only 3 visitors per week are coming back for another look -- and the average time spent browsing the site is less than a minute, suggesting that most visitors aren't even reading a post. At this point, I have to ask myself whether I can justify the time I spend on this blog, even if it isn't much time.

Six months ago, I disabled the comments feature since I was essentially the only one making any comments (sometimes following up on the topics raised in the original post). Today, I'm turning the comments back on -- and I'm asking for your feedback: Should I continue posting to starstuff.blogspot.com? After the new year, based on the comments you leave or email, I'll either continue for another year or hang up my blogging hat. In either case, it's been a great experience, and the archive is here for everyone to enjoy.

Telescope Philanthropy

In the early history of astronomy, pioneers like Tycho Brahe depended on the generosity of kings to fund their science. Since the mid-20th century, this role has largely been supplanted by the government, through agencies like the National Science Foundation and NASA. Recently, with the federal budget slumping under the weight of excessive military expenditures and declining tax revenues, government funding for science has stagnated. But at the same time, a new class of philanthropists has emerged to help fill the gap.

Last week, Intel founder Gordon Moore announced that his foundation would donate $200 million to help build an enormous telescope with a mirror thirty meters (100 feet) in diameter. Imaginatively called the "Thirty Meter Telescope" (TMT), the California-led project is one of several competing efforts to build the next generation of large telescopes for astronomy research -- including the "Giant Magellan Telescope" (GMT) and an even larger European project called the "OverWhelmingly Large" (OWL) telescope, with a 100-meter mirror. All of these projects seek to produce the sharpest images ever obtained from a ground-based observatory (10 times sharper than images from the Hubble Space Telescope), offering new insights into the history and fate of the universe.

Moore's grant to the TMT project is just one example of a growing trend toward private funding for astronomy research. Last January, Google announced a partnership with the Large Synoptic Survey Telescope (LSST), which plans to image the entire sky every three nights beginning in 2013, and Microsoft co-founder Paul Allen is funding the latest efforts by the Search for Extra-Terrestrial Intelligence (SETI). Several global telescope networks have also received private funding, including the Whole Earth Telescope (from the DuPont Foundation), the Stellar Oscillations Network Group (from Danish beer giant, the Carlsberg Foundation) -- as well as the Las Cumbres Observatory Global Telescope Network, which was recently endowed by a retired silicon valley technology guru.

While most funding for science continues to come from government sources, it is encouraging to see the entrepreneurial spirit blossom among astronomers -- and to see it rewarded with the patronage of new donors who hold a special place in their hearts for the stars.

Adopting a Star

Whenever the holiday shopping season rolls around, I consider the idea of setting up an "Adopt a Star" website to help fund scientific research. A quick Google search persuades me to abandon the idea -- the Internet is already full of such sites, and most of them are far more sophisticated than anything I would have time to create. Anyone who cares to fork out $19.95 can name a star "Lula", after their cute Bichon Frise puppy -- they even get a certificate with a star map and the vital statistics of their stellar namesake. But what are they really buying?

The International Astronomical Union (IAU) is the only "internationally recognized authority for naming celestial bodies... and names are not sold". In fact, with the exception of a few bright stars that have ancient traditional names, most of the stars in the sky only have boring old catalog numbers. The IAU does name comets after the discoverers, and astronomers who find new planets or asteroids in our solar system are allowed to suggest names for them (though they can only be named after people who have been dead for more than 100 years, which obviously limits the commercial possibilities). None of the websites that allow you to "buy" or "adopt" a star are affiliated with, or endorsed by, the IAU. So what are these businesses selling?

It's important to distinguish between companies that allow you to "adopt a star" and those that say you can "buy a star name". Although both are engaged in essentially the same business, the representation of the transaction as an "adoption" is more intellectually honest. When you "adopt a highway" it's understood that you do not thereby own a section of a public road. Instead, you agree to keep the adopted stretch free from garbage in exchange for a blue sign on the roadside acknowledging your effort (and possibly persuading drivers to stop at your coffee shop). In the case of stars, your only responsibility is to pay the $19.95 -- the company then lists your name beside the chosen star on their website, and maybe sends you a glossy certificate. One of the best operations I discovered recently is actually run by scientists to support their research. The website resembles the vision I had for "Google Sky", which I wrote about last December, and cleanly separates the commercial portion of the site from the main section that is meant to be a tool for astronomers and the general public.

Allowing anyone to adopt a star is fairly harmless, and most people probably realize that astronomers around the world do not subsequently publish scholarly articles detailing their in-depth decades-long study of "Lula" the puppy star. For those who don't realize that it's just a novelty gift, I have some very nice real estate on the Moon that promises to be really hot property in a few years...

Alien Solar Systems

Last week a team of scientists in California announced the discovery of the fifth planet orbiting a distant star similar to our sun. The star is known as "55 Cancri", and is located 41 light years away in the constellation Cancer. This star now holds the record for hosting the largest known planetary system outside of our own. Only one other star (called mu Arae) is known to host four planets, while triple-planet systems have been documented around another half-dozen stars.

Since 1995, more than 220 planets have been discovered in orbit around other stars. The overwhelming majority of these planets have been found by their gravitational influence on the star that they orbit. We tend to think of a planet as simply moving around its star -- but even small planets exert a gravitational tug on the star that causes it to wobble around slightly in space. Astronomers can measure this wobble, essentially by passing the light from the star through a prism to spread it out into all of its colors (think of the famous Pink Floyd album cover) and then carefully measuring the positions of dark lines that appear where different chemical elements like hydrogen and helium absorb light near the surface of the star. The color corresponding to the position of these dark lines moves around as the star wobbles -- basically for the same reason that the pitch of an ambulance siren sounds different when it is moving towards you or speeding away (the effect is known as the Doppler shift).

The team has been monitoring 55 Cancri for more than 18 years. Since the wobbles caused by the five planets are all happening at the same time, and with different orbital periods, it took a long time to isolate the wobbles caused by each planet individually. The outermost planet in the system is about four times the size of Jupiter, and it takes 14 years to orbit the star. The other previously known planets are similar in size to Neptune, Jupiter, and Saturn, but they orbit the star relatively close in -- circling every 3, 15, and 44 days (all much faster than Mercury orbits the Sun). The newly discovered planet falls somewhere in between, orbiting the star in about 260 days. Since 55 Cancri is a little fainter than the Sun, this places the new planet inside an Earth-like "habitable zone" where liquid water can theoretically exist. Although the planet is roughly the size of Saturn, it could have large Earth-like moons where water and potentially life could survive (Saturn's largest moon "Titan" is bigger than the planet Mercury).

It's only a question of time before astronomers discover more and larger planetary systems around distant stars. The longest running surveys have been operating for less than 20 years, so even in the best case we would not be able to detect Saturn, Uranus, or Neptune if we were watching the Sun from a distance. As the technology improves we should also begin finding smaller planets, closer to the size of the Earth. In the future, people might wonder what all the fuss was about over this little five-planet system around 55 Cancri.

Splitting the Sky

Now that the Intergovernmental Panel on Climate Change (IPCC) and Al Gore have been awarded the Nobel Peace prize, the debate about global warming can shift from whether or not the human population is primarily responsible, to how we should design a solution. The idea that is currently most popular with politicians involves setting a cap on carbon emissions, distributing free permits to corporate polluters, and then allowing them to trade the permits amongst themselves. Since it establishes a free market for pollution rights, this "cap and trade" system is supposed to lead to the most efficient reduction in carbon emissions -- allowing the companies that learn how to reduce their pollution to profit by selling their permits to companies that have more trouble.

It sounds like a reasonable system, and it has even been used successfully in the past to reduce sulphur-dioxide emissions -- the leading cause of acid rain. But it suffers from a fatal flaw: the polluters do not pay the costs of the efficiency improvements, but instead transfer the burden to consumers. A slight modification of this system, popularized by the book "Who Owns the Sky?", divides the pollution permits equally among the population and forces the polluters to purchase them from us! Again the costs are eventually transferred back to us through products and services -- but the average person comes out about even. This has the advantage that it also establishes an incentive for individuals to reduce their pollution-generating consumption: if you drive an efficient car or reduce your overall energy use, you can can earn more from selling your carbon permits than you pay back to the polluters.

On a national level, this modified system seems pretty workable -- but how do we divide pollution rights between countries? The most obvious answer would be to split the sky evenly among the entire population of the planet -- every person gets an equal share. But the obvious answer may not be the best answer, because it effectively rewards countries with large populations -- and population is a major factor in the growth of global warming emissions. What really matters for each country is the relationship between its biocapacity (the natural resources within its borders, and how they are used) and the product of population and consumption (the total drain on those resources). Some countries have more biocapacity than their population consumes, while others have ecological deficits. If the global distribution of carbon permits were based on biocapacity, it would force countries that are far out of balance (whether due to consumption, population, or both) to purchase permits from countries that manage their resources more responsibly. This establishes the right incentives for both consumption and population.

With the right system, we can transform our societies and bring them back towards a balance with the resources of the planet. If we start reasonably soon, we might even avoid the most unpleasant consequences of pushing the limits of nature.

Science and Politics

During the U.S. election season, which seems to stretch on forever compared to most modern democracies, it's more difficult than usual to find science in the headlines. I'm fairly certain that good science continues to be produced, with press releases diligently prepared, while presidential hopefuls give stump speeches along the campaign trail. But most of the time, science just doesn't seem to make the cut. The exception to this general rule occurs when science and politics collide -- when the candidates begin to address the issue of government interference in research, where policymakers lose access to unbiased information.

This week, on the 50th anniversary of the launch of the Russian sputnik satellite, one high-profile candidate delivered a speech blasting the current administration's "war on science", and outlined strategies to shield government scientists from political pressure. Recent examples of scientific research being either suppressed or distorted by government managers -- many of whom were appointed more for their loyalty to an ideological agenda than for any expertise in the relevant discipline -- are most obvious in the area of climate change research. But other research areas have also been politicized, including the science of food safety, air quality, and forest management, to name just a few.

As with many issues, politicians are following rather than leading public opinion. The campaign to restore "scientific integrity" to decision making has recently been championed by the Union of Concerned Scientists. This grassroots organization has sponsored surveys of government scientists and circulated a petition, now with more than 12000 signers, to keep politics out of science. On the specific issue of embryonic stem cell research, which has had limited federal funding imposed by the current administration since August 2001, several prominent celebrities have also played an active role. One of the current group of candidates promises a return to "evidence-based decision-making" in the next administration, something most scientists would undoubtedly welcome.

Like oil and water, science and politics simply do not mix. The government might shake things up for awhile, but -- honoring the finest traditions -- science will eventually rise to the top.