Centuries ago the stars were believed to reside just beyond the planets of our solar system.It never fails to astound me how big the Universe is—how far away even the nearest stars are, let alone other galaxies scattered from here to near infinity….

How do we know how far away celestial objects are? This shouldn't be taken for granted, as it's not as straightforward as sounding the depth of the ocean floor with sonar, or determining the range to an object by bouncing radio waves off it and timing the reflection.

In fact, we have "pinged” the nearest celestial objects with radar to determine their distances very accurately. Examples are the Moon and Venus, where round-trip lightspeed travel is measured in seconds or minutes.

Before radar, the scale of the Solar System had to be determined geometrically, by observing events like Venus or Mercury transiting the face of the Sun from different locations on Earth and triangulating. Even this technique requires telescopes, which we've had only four hundred years. Before that, figuring out distances to just about everything except the Moon was mostly guesswork. In fact, it wasn't too many centuries ago that the entire Universe was believed to be not much larger than the Solar System—the Sun and it's nine…excuse me…eight planets—as we know it today.

Once the distance from Earth to the Sun was figured out, that length (the "Astronomical Unit”) in effect became a basic measuring rod for working out distances to everything else, by one means or another.

As Earth orbits the Sun, the direction from which we see stars shifts minutely, and we can observe a small change in a star's position compared to the more distant "background” stars. You can see the same effect by holding a finger in front of your face and looking at it alternately with one eye, then the other.

The geometry of this observation is a simple triangle, whose base is the distance between your eyeballs and whose legs are the lines from each eyeball to your finger. By knowing the length of the base, and observing the change in viewing angle against the background, the length of the legs (distance from your eyeballs) can be calculated.

In the case of Earth and a nearby star, the "eyeballs” are the Earth at two ends of its orbit around the Sun (six months apart) and the "finger” is the star.

But this measuring of distance by "trigonometric parallax," as it's called, only works for the nearest stars, as the minute shift in the star's apparent position diminishes with distance.

As astronomers learned more about the distance to nearby stars, they determined how to relate their temperature and mass to their actual brightness, and it became possible to estimate the distance of many stars by measuring their apparent brightness, with an understanding of how the brightness of light weakens with distance.

To measure the depths of space between us and galaxies far, far away, in which individual stars are indistinguishable from the overall galactic glow, we can turn to certain types of supernovae: individual stars that temporarily shine brightly enough to be observed and measured. Like the flare of a match struck in the dark night, the brilliance of the flash reveals how far away the striker stands.

We have built up our knowledge of the Universe's vastness over the past couple centuries, working out the problem from the near to the far. Even as science and technology have made the world on which we live smaller, it has done exactly the opposite to the Universe….

Google Mars view from the slopes of the Olympus Mons caldera. Credit: Google Earth

I was sitting at my computer the other day, quietly exploring minute details of the surface of planet Mars, when I realized once again that in my lifetime planetary exploration has gone from telescopic-view-only to robotic rovers poking microscopes close up at Martian geology!

Did I say quietly exploring the surface of Mars? Yes I did—and you can, too. First of all, if you're not familiar with Google Earth, please go and google Google Earth and get your free download today (this is NOT a sales pitch!). A modestly powered computer with a decent graphics card is all you need to probe every nook and cranny of planet Earth, sometimes to the detail of spotting people walking in the streets….

But there's a magic button on Google Earth (it looks like planet Saturn, for some reason) that instantly transports you to planet Mars—Google Mars, that is. It's a simple button click to explore Mars, Google Earth style.

This detailed digital Mars has been created with all of the data collected by the fleet of robots we've sent—from Viking to Mars Global Surveyor to Mars Odyssey to Mars Express to Mars Reconnaissance Orbiter (MRO), and of course Pathfinder, Phoenix, and the Mars Exploration Rovers, Spirit and Opportunity.

First on my itinerary was Olympus Mons, that extinct, Arizona-sized shield volcano that rises 15 miles above the average global terrain. Swooping into the San Francisco Bay-sized caldera, I got a sense of what it would be like to be there, standing on the caldera rim. There were even strips of super-high resolution imagery provided by MRO's HIRISE camera, allowing me to hover maybe a hundred feet above the ground and see rocks and piles of sand!

Next on the list had to be that other famous gargantuan feature, Valles Marineris, the "Grand Canyon of Mars" which, if it were moved to Earth, could stretch from Oakland, California to New York City—putting Grand Canyon National Park within a day's drive of anyone in the US…. Google Earth/Mars has a flight simulation mode that allows you to pilot an aircraft over and through (and into) the terrain.

Like a kid in a science supply shop (okay, that's the kind of kid I was), next I hopped on up to the landing site of NASA's Phoenix lander, on the wide flat plains near the Northern Polar Ice Cap. Yup, those plains are really flat. To my delight, I found that someone had inserted a panoramic picture taken by the orbiting MRO spacecraft when it captured Phoenix descending through the atmosphere.

Onward, planetary explorer…. I had to feel—not just see, but feel—what the landscapes that Spirit and Opportunity have been exploring for 5 years are like. On Spirit's side of the globe, Gusev Crater, I poked about the Columbia Hills, following in the tracks of the robot. Over at Opportunity's digs, I dropped into Victoria Crater, enveloping myself in "Street View"-style panoramas that almost set my feet down on Martian soil.

Okay, I could go on telling you about my adventures on Mars for days—but since you can do it yourself now, I'll let you go to it. Have fun, and send back a postcard! (Which, by the way, you can do from Google Mars….)

Credit: NASA.

When the LCROSS satellite, nicknamed Centaur, smacks into the south pole of the moon in late October, it is expected to produce a plume of dust 37 miles high, which may be visible from Earth with a good backyard telescope. It will be visible in an arc from Hawaii to Texas.

If you'd like to catch the impact, the Chabot Space and Science Center in Oakland is hosting a Shooting the Moon star party on the night of impact. Morrison Planetarium in San Francisco may host a star-gazing event, as well, but it hasn't been announced yet. And you could check in on other observatories in the Bay Area, as well: Lick observatory in the Santa Cruz mountains, Foothill observatory in Los Altos Hills, Sonoma State observatory in Rohnert Park, and the Fremont Peak observatory in the East Bay.

Not all of them will be open to the public; for instance, Foothill Observatory will be closed to the public, because they’ve been asked to take photographs of the event.

If you know anyone with a 10-inch telescope (that's the diameter of the lens), you can bet that telescope will be lined up to look skyward when the LCROSS probe hits the moon.

If the impact goes well, then the plume above the moon's surface could hover there for hours. It will make its own crater on the moon about 6 feet deep and 30 yards wide, so the plume of dust will not be visible to the naked eye, or even through binoculars.

The exact date, time and even the exact location of the impact have not yet been determined. Keep your eye on NASA's site for more information.

And one aside: This impact will not hurt the moon, or send it off its orbit. That may seem apparent to many people, but NASA Ames officials say those are the most-asked questions about the project.

Listen to the Crash Landing radio report online.

The Hubble Space Telescope being serviced by Space Shuttle
Atlantis astronauts in May 2009. Credit: NASAFour hundred years ago, Galileo built his telescope and became the first on record to point the new device (invented the previous year) at objects in the sky. Today (in fact, even as I write!) what has become a symbol for the current state of evolution of the telescope—the Hubble Space Telescope–is being repaired and upgraded by the crew of the Space Shuttle Atlantis…for the last time.

Galileo's telescope had a magnification of only about 27x, allowing him to see that Venus has phases like the Moon, Jupiter has four large moons of its own, Saturn does not appear as a simple disk but has unusual "projections" to either side, and the Milky Way contains far more stars than is apparent to the naked eye. And though these are features that can be seen through the least powerful home telescopes today, Galileo's observations changed the way we look at the universe.

Hubble has done the same thing, but on a modern scale of magnitude. Not a large telescope by the standards of ground-based behemoths like Keck in Hawaii (Hubble's primary mirror is 2.4 meters in diameter), Hubble's "edge" is it's location in space, orbiting the Earth over 300 miles high, outside of our atmosphere. Particularly in its earlier days before ground based telescopes were using adaptive optics techniques to compensate for atmospheric distortion, Hubble's vision on the universe was unparalleled in its clarity.

Here's is a recap of a few of the many big discoveries Hubble has made possible:

Dark Energy: By accurately measuring the distance and velocity of distant supernovae, over a large range of distances, Hubble has refined out knowledge of the rate of expansion of the universe–leading to the discovery that the expansion of the universe is actually accelerating, contrary to what was expected. Scientists suggest the existence of a mysterious "dark energy" throughout the universe that exerts an antigravitational repulsive pressure on the cosmos.

Age of the Universe: Since Edwin Hubble (for whom the Space Telescope was named) discovered that the universe is expanding, astronomers have been trying to determine how long ago the expansion began–how long ago the "starting gun" of the Big Bang was fired, and thus the beginning of the universe. Through precise observations with the Hubble, astronomers in recent years have been able to peg it between 12 and 14 billion years. (Most recently, observations made with the WMAP mission have honed that down to 13.7 billion years, give or take 0.13 billion.)

Supermassive Blackholes: Hubble found the clues that point to the existence of "supermassive" blackholes at the heart of maybe most–or every–galaxy. The Milky Way's own central blackhole has a mass equivalent to four million Suns.

Stellar Dust Disks: Before the first extrasolar planets were actually detected, Hubble observations revealed that flat disks of dust encircling young and developing star systems–aka "protoplanetary disks"–is commonplace. This has given us a glimpse at what our own solar system may have looked like before the planets formed.

It has been seven years since the last Hubble servicing mission, with another servicing scheduled a few years ago cancelled in the wake of the Columbia disaster. Several failing systems will be repaired or replaced this time, and other instruments are receiving upgrades that will make Hubble more powerful than ever in its declining years.

This mission to service the Hubble will be the last. Since NASA is retiring the Space Shuttle fleet after 2010, we will no longer have a space vehicle large enough to carry upgrade and replacement equipment to and from the Hubble. After that, the next new big space-based descendent of Galileo's spyglass will be the James Webb. Stay tuned…

Cal Poly's CP-4 mini-satellite in orbit. Credit: The Aerospace
Corporation.

It's a classic engineering story - a garage inventor spends years working in isolation, only to produce something that gets the attention of the world. Ok, the CubeSat story may not be quite as romantic, but it does have a lot of the same ingredients.

Professors at Stanford University and Cal Poly created CubeSats - 10 by 10 by 10 centimeter mini-satellites - as enginneering projects to give their students hands-on experience. Compared to standard satellite missions, which can run hundreds of millions of dollars and take years to complete, CubeSat missions are mean to be done cheaply and quickly.

CubeSat is also a standard - a basic blueprint that any university program can use. CubeSats are actually known as "FedEx satellites," since universities can mail them to Cal Poly to arrange a ride into space. They've created launching devices called P-Pods (a box that fits the CubeSats perfectly) so they can piggyback on larger rocket launches. Once the main cargo is deployed, the P-Pod releases the CubeSats into orbit. Depending how high they are, CubeSats can orbit for more than a decade before they burn up in the atmosphere.

What started at universities has spread - NASA, Boeing and other aerospace companies all have mini-satellite programs. Despite the small size, CubeSats are actually able to do valuable research. They can space test new technology, submitting it to all the rigors of space travel like solar radiation and launch stress. Recreating those conditions on the ground can be very expensive.

CubeSats can also gather scientific data. On Tuesday, NASA will be launching Pharmasat, which they hope will be their second nano-satellite in orbit. It will carry yeast samples, and once in orbit will hit them with an anti-fungal to see if their resistance is increased in space. NASA has previously observed that some bacteria are more resistant to antibiotics in space, something that could be dangerous for future human space travel.

You can tune in on Tuesday evening for the Pharmasat launch. Three other CubeSats from Cal Poly and other organizations will also be getting a lift into space.

Listen to the Do-It-Yourself Mini-Satellites radio report online, and see our Web Extra: Mini-Satellites Slideshow.

Artwork from Jules Verne’s 1865 novel, From the Earth to the MoonLaunching a spacecraft bound for the Moon with the deliberate intention of striking the Moon in a spectacular impact!

Sounds like something out of a Jules Verne novel… but that's exactly what NASA's up to this year with the upcoming LCROSS (Lunar Crater Observation and Sensing Satellite) mission, scheduled for launch on June 2nd and impact sometime in October– exact date TBA.

And it's not unprecedented, either: the Lunar Prospector spacecraft back in 1998/1999, whose instruments detected possible signs of water ice in craters around the Moon's poles, was crashed into the Moon's South Pole at the end of its mission. The aim was to blast up a cloud of material from the lunar surface and spectroscopically analyze the plume in search of water vapor. None was detected then, but that's where LCROSS comes in.

LCROSS will seek to verify the presence or absence of water ice and related hydrated materials buried at the bottom of a permanently shadowed crater floor on the Moon's South Pole. Water ice cannot persist on any part of the Moon's surface that is subjected to sunlight, but because of the Moon's low axial tilt with respect to the ecliptic (the Sun's apparent annual path in the sky)– only about 1.5 degrees– there are craters at the Moon's poles whose floors never see the light of day, all month long and year round. Water ice could persist near the surface in these places.

LCROSS consists of two pieces: a "Shepherding Spacecraft" that will guide the whole affair to the proper location on the Moon's South Pole, and the Centaur rocket stage that propelled the spacecraft to the Moon. The pair will separate, and the Centaur rocket will become the primary impactor, striking ground and producing a crater and plume of ejected material. Viewing the event from above, the Shepherding Spacecraft will use cameras and other instruments to analyze the plume from a distance, and will then follow the same course as the Centaur, descending four minutes after impact through the ejected plume and analyzing material samples as it falls.

Then, the Shepherding Spacecraft, too, will impact the Moon– and the plume it kicks up may well be visible through modest sized telescopes on Earth. We're planning to watch the explosion live through our telescopes at Chabot, weather permitting. Keep an eye on our website for details.

Now, back to Jules Verne for a moment. The launching of a projectile with the intent of striking the Moon was indeed the subject of one of his novels, From the Earth to the Moon, published in 1865. Fired from an enormous cannon, the goal of that post Civil War mission was to catch the attention of anyone living on the Moon, to open up a line of communication with their civilization.

My wife asked me if crashing a probe into the Moon would have any harmful effects, particularly if in fact there is any form of life (subsurface microbes or such) living there. Well, certainly, if you happen to be a lifeform living at ground zero of the impact… but the fact is the Moon is frequently struck by meteorites much larger than the LCROSS impactor anyway. To paraphrase Douglas Adams, "that kind of thing goes on all the time."

One last fun tidbit about the Jules Verne novel: the launch site for his cannon-fired projectile was a place in Florida, 50 miles south of Tampa Bay, and only about 135 miles from the Kennedy Space Center, from which LCROSS will be launched…

NASA/Mars Reconnaissance Orbiter; Fans of dark dust on Mars'
southern ice cap, apparently blasted from beneath the ice
by thawing carbon dioxide."

It's spring again, that time of year when my thoughts return to…blasts of carbon dioxide gas jetting up from beneath the frigid layer of dry ice below, carrying rusty red dust in plumes that jet toward the pale skies….

At least, that's what happens at the polar ice cap on the planet Mars. I'd sure love to be there to see it, even if there are no flowers in bloom. Still, there seems to be plenty of "blossoming" going on….

NASA's Mars Reconnaissance Orbiter—the spacecraft with that high powered camera that could spot a beach ball on Mars' surface—has captured images of the aftermath of some of Mars' springtime polar action. Appearing as dark fan-shaped bursts strewn across the thinning springtime polar ice, these features are explained as plumes of Martian dust that have settled after being blasted into the air by releases of gas pressure from under the surface of the ice.

To describe what's going on, let me paint a picture of the Martian polar region as it emerges from the deep freeze of winter into spring.

Mars' year is almost twice as long as Earth's—and so too are its seasons. Winter at the southern pole of Mars lasts almost six months. In that time, the normally freezing temperatures on the Red Planet plummet to as low as -225 degrees Fahrenheit at the pole. During this time, Mars' permanent water ice cap acquires a layer of frozen carbon dioxide (dry ice) on top, formed from carbon dioxide freezing directly out of the atmosphere.

This seasonal dry ice cap also forms around the edges of the water ice cap, covering adjacent ice-free surfaces as well. The carbon dioxide ice cap may grow to as much as a meter thick.

Then, as spring approaches and the ice cap gradually comes out of the dark and receives more and more sunlight, it begins to warm up (though don't get the impression that it is ever "warm" anywhere on Mars' surface! Air temperatures recorded by the Viking landers in Mars' more temperate latitudes was barely ever higher than 1 degree Fahrenheit). Spring Equinox in Mars' southern hemisphere was on December 26th.

As the layer of solid carbon dioxide heats up, its ices turn to gas, both at the top of the layer and beneath it as well. The gases forming underneath build up pressure, which seeks a path to escape. Evidently the pressurized carbon dioxide gas can actually carve channels in the Martian soils under the ice as it flows—said channels have been seen in the past after the seasonal ice cap dissipates entirely.

When the gases find a weak point in the ice, they can erupt upward, bursting into the air, sometimes carrying dust with it. The dust rockets skyward and is blown by prevailing winds, settling out on the ice in great dark fans—which is what Mars Reconnaissance Orbiter has shown us.

Ah, to be on Mars in springtime….

Yuri Alexyevich Gagarin, "Columbus of the Cosmos" Last Thursday evening, over 3500 people came to the California Academy of Sciences to help celebrate Yuri. This gathering was not the only celebration of its kind. Two-hundred and eight parties in forty-six countries on eight continents celebrated Yuri's Night between April 6 and 12th of this year.  So who is Yuri and why does he deserve such accolades?

Yuri Alexyevich Gagarin was a Soviet cosmonaut.  He was the first human in space and is often referred to as "the Columbus of the Cosmos".   His spacecraft Vostok-1 orbited the Earth on April 12, 1961 for the duration of 108 minutes.   Yuri's Night, usually celebrated on April 12^th celebrates this historic first flight.

Yuri's Night also celebrates another April 12^th anniversary notable in the annals of space travel.  Twenty years after Yuri Gagarin's historic flight, the first NASA space shuttle flight, STS-1 was launched into space.  STS is short for Space Transportation System.  NASA names each flight STS with the chronological number after it.  STS-1 was launched on April 12, 1981; the shuttle orbited the earth 37 times during a 54.5 hour mission.

Since 1961, our interest in space and the exploration of its depths has magnified.  Recently NASA launched the Kepler mission.  On March 7^th, 2009, the Kepler Mission successfully launched from Cape Canaveral, Florida.  Kepler, which is a specialized telescope, was designed to find the first Earth-size planets orbiting stars within a "habitable zone". A habitable zone is an orbit around a star that would enable a planet to formulate and upkeep an atmosphere and the ability for water to form in pools on the planet's surface.  Liquid water is believed to be essential for the formation of life.  Thus from the nascent flight of orbiting our own Earth, space travels has evolved to look amongst other start.  This progress is certainly something worthy of celebration!

An exhibit on the Kepler Mission along with other NASA initiatives like SOFIA, LCROSS and NLSI fascinated guests last Thursday night.  For one guest, meeting Buzz Aldrin in person was the highlight of his night.   My favorite aspect of the evening was a 3-D rendered tour of the moon and neighboring space.  I am anxious to see what will be the new annal of space exploration when April 12^th and Yuri's Night comes around again in 2010.

Our Sun has a well-observed cycle of rising and falling magnetic activity that runs its course about every 11 years. But as cycles in nature teach us time and time again, you usually can’t set your watch or your calendar by them.

The Sun seems to be unusually quiet these last few years– and solar scientists are excited by this long, deep slumber of activity because it is the first of its kind that has occurred since modern (space-based) solar observation began back in the 1960s.

The Sun is a huge ball of hot, electrically charged gas (plasma– mostly hydrogen and helium ions and electrons). Its constant internal motions of plasma– the rising and falling of convection cells, the non-uniform rotation of the Sun that involves a lot of twisting and sheering– generate magnetic fields, as any kid who has built an electromagnet might guess. In an electromagnetic, an electric current (moving electrons) generates the magnetic field.

The Sun’s magnetic fields can grow quite strong in areas, generated beneath the Sun’s visible surface (photosphere) and rising up through that surface and into the Sun’s enveloping atmosphere. At the photosphere, the magnetic fields tend to suppress the rising convection of plasma, choking the flow of heat from the interior to the surface and making spots that are less hot than the general surface (4000 degrees as opposed to 6000 degrees). The cooler spots are less bright, and we call them sunspots.

The same magnetic fields that leave their mark on the photosphere as sunspots rise into the solar atmosphere, where their sometimes violent twisting and interaction heats the gases there, and can power violent explosions such as solar flares and coronal mass ejections, both of which can affect the Earth.
So, sunspots are a visible sign of magnetic activity, and over the last 400 years of regular observations and counts of sunspots, a distinct 11-year cycle from one peak of activity to the next has been identified. Between peaks of activity (called solar maxima) are periods of relative "quiet," magnetically speaking, when there are few if any sunspots observed, and events like solar flares and such are not common.

We are currently in the midst of a solar minimum– the last solar maximum that occurred was around 2000/2001. But what has scientists buzzing right now is just how "deep" a sleep the Sun seems to be in. 2008 was the quietest year for the Sun on record since the beginning of the space age. Out of the 366 days last year, on 266 of them the Sun was completely spotless, which is well below "normal" for a solar minimum year.

What does it mean? Well– that’s difficult to say right now. Scientists are still trying to understand why the Sun experiences its 11–year cycle at all. And it’s not unprecedented; the Sun has experienced "deep minima" before. In 1913 there were 311 spotless days. Other deep minima have been seen in the sunspot record, and in almost every case normal solar activity returned; the next solar maximum is expected to peak in 2011 or 2012– perhaps 2013.

There is no indication that the Sun will remain quite and mostly spot free for an extended period– such as it did in the 17th Century, when the Sun remained quite for about 70 years!

A scale model of the LCROSS payload.

Update: LCROSS will now launch with the Lunar Reconnaissance Orbiter on Thursday, June 18thfrom the Cape Canaveral Air Force Station in Florida. If the launch goes well, LCROSS would be on track to impact a target crater on the lunar South Pole in early October and then we may finally know if water exists on the moon, possibly buried deep as ice within the lunar soil. You can even watch a live feed of the LCROSS launch and hear from experts about the mission beginning at 1PM in the Exploration Center at NASA Ames Research Center in Moffett Field.

With a price tag of 80 million dollars and a little more than two years in the making, the LCROSS spacecraft will begin its voyage atop an Atlas V rocket. Shortly thereafter it will shepherd the upper stage of the rocket in an orbit around the moon to position it in place for a colossal impact that will kick up a cloud of lunar dust forty miles high. The goal is to see if water exists on the moon and if it does, buried deep beneath the lunar soil, accumulating over millions of years of impacts with comets, it would accelerate our efforts to establish a permanent lunar base. Think of it as a rest stop to refuel (oxygen is an essential ingredient of rocket fuel) before arriving at the next closest planetary body, Mars, a journey which takes roughly 600 days, or 200 times longer than a trip currently to the Moon from Earth.

The avid QUEST viewer may recall that we covered the LCROSS mission in the first episode of QUEST back in 2007. A lot has happened since then, including most notably a change in the launch date which at the time of this post was scheduled for May 20th, 2009. Peter Schultz's vertical gun range has been outfitted with some dizzyingly high-tech cameras, which are capable of recording at tens of thousands of frames per second (one can record at one million frames per second) to capture the most minute progressions of the lunar impact simulations performed with the thirty-foot tall vertical gun. The suite of nine instruments aboard LCROSS, known as its "payload", has been mercilessly subjected to thermal, vibration and acoustic testing to make sure they can withstand the effects of launch and the harsh celestial environment. And then there's the spacecraft itself which we weren't able to show you in 2007 because the spacecraft still had to be transformed from a set of designs into a compact, robust structure the size of a small car by a team of sharp, young Northrop Grumman engineers. Moreover, amateur astronomers, armed with telescopes ten inches or more, are now being encouraged by NASA to share their images of LCROSS' historic lunar impact.

One of the most impressive attributes of the LCROSS mission is its rapid turnaround and cost containment which in turn highlight the innovative production model that was essential in making LCROSS a reality. Imagine the spirit of Silicon Valley, with its entrepreneurial zeal and efficiency, fusing with some of the sharpest minds in astrophysics and aeronautical engineering, and you have a glimpse of the unique nature of this small but nimble mission which just may forever change our understanding of the moon and its secrets.

Watch the LCROSS Rocket to the Moon" television story online.