ISS

ISS
The final frontier.

Sunday, January 15, 2012

The End of Phobos-Grunt

The doomed Russian spacecraft, Phobos-Grunt has finally come crashing back to Earth.  I didn't want to admit to myself that it was going to end this way, but now there is no denying it.  Earlier today, Phobos-Grunt re-entered Earth's atmosphere, and while some of it burned up, debris did come down in the Pacific Ocean, west of Chile.  So ends the latest Russian interplanetary mission.


Artist's conception of the Phobos-Grunt spacecraft.

Phobos-Grunt was intended to fly to the Martian moon, Phobos, and return a soil sample via a small re-entry capsule.  It would have been the first return sample from the Mars system by any nation.  However, shortly after the November launch, ground controllers in Moscow lost contact with the spacecraft.  Apparently, two planned rocket burns never occurred, and the spacecraft never left Earth orbit.  For weeks, controllers tried to re-establish contact, and except for one short communication, contact was never fully regained.  Hope remained for some weeks that the spacecraft could be salvaged, but, clearly, that never happened.

Russia (and before them, the Soviet Union) has had a long history of mission failures to the red planet.  Of the nearly 20 missions Russia has aimed at Mars, none have been complete successes, and only a handful have partially succeeded.  The Phobos-Grunt disaster is reminiscent of the Mars 96 incident, where a complex Mars orbiter and lander failed to leave Earth's orbit and burned up over the Pacific.  This latest failure, coupled with a recent spate of other space failures, has Russia's government putting the pressure on those in the space industry.  President Medvedev even went so far as to threaten prosecution of engineers and scientists who work on failed missions.  Succeed or rot in prison - a truly sound policy!

Where Russia goes from here isn't yet clear.  Russia takes space exploration seriously, and despite this latest failure, I believe they will continue with interplanetary science missions.  There is some talk of the Russians being involved with the upcoming ExoMars mission.  ExoMars is a collaboration between the ESA and NASA, and would launch an orbiter to Mars in 2016.  That orbiter could be partially outfitted with Russian instruments and be launched atop a Russian Proton rocket.  A rover would follow in 2018, but it is not yet known if Russia would help with that part of the mission.


Stuck in orbit, Phobos-Grunt as seen from Earth (Ralf Vandebergh).

Russia is an important international partner in humanity's continued exploration of space.  With luck, they will rebound from this setback, and contribute on future missions to the red planet and beyond.

Wednesday, January 11, 2012

Planets of the Milky Way

A new study estimates that there may be as many as 160 billion planets in our Milky Way Galaxy.  That's about 1.6 planets per star, many more than were thought to exist just a few years ago.  Most of these worlds are thought to be rocky type planets, as opposed to gas giants.  Just how many of these planets could support life, however, remains to be seen.

Interest in planets outside of our solar system, known as exoplanets, has increased dramatically in the last few years.  The amazing success of NASA's Kepler mission has fueled much of the interest.  To date, the orbiting Kepler telescope has identified nearly 3000 exoplanets.  Kepler does this by measuring the slight decreases in the amount of light a star appears to emit when a planet passes between the star and the telescope.  This is called the 'transit method' of exoplanet detection.  After a candidate exoplanet is identified this way, scientists employ ground based telescopes to back up Kepler's findings.  It is only after this that an exoplanet can be confirmed to exist.  Around 700 of Kepler's candidate exoplanets have been confirmed, and it is estimated that up to 80% of all candidates will indeed turn out to be exoplanets once further observations are carried out.


Artist's depiction of the Kepler telescope (NASA).

After Kepler identifies a candidate planet, observing that world from ground based telescopes can be done in one of a few ways.  Scientists can measure small wobbles in a star's movement caused by the gravitational pull of planets orbiting the star.  This is called the 'radial velocity' method.  Both this and the transit method are biased toward large planets that are close to their parent stars, however.  Another method that doesn't have the same bias is called 'gravitational microlensing.'  This is where a star is observed just as a closer body, such as another star, passes in front of it.  The gravity of the closer body bends and magnifies the light of the distant star, similar to a lens.  This can help resolve the relatively tiny exoplanets that may be orbiting the star.

The big question now becomes: Are these worlds habitable?  The Kepler telescope, by itself, cannot tell us this.  However, we can infer several things from Kepler's findings.  For life, as we know it, to exist, a planet must harbor liquid water.   For that to happen, a planet must be in its star's 'habitable zone'; a distance, particular to each star, where it is neither so cold that water freezes, nor so hot that water boils away.  Earth, for example, is right in our Sun's habitable zone.  Venus, with its 480 degree Celsius surface temperature and runaway greenhouse effect, is just a little too close to the Sun to be in the habitable zone.  Kepler has already identified exoplanets that are in their habitable zones, and is sure to observe more in the coming years.  It will be up to other telescopes, like the as yet to be launched James Webb Space Telescope (JWST), to probe deeper into these potentially life harboring exoplanets.  JWST will have the ability to measure the atmospheres of exoplanets, and depending on the composition, that could reveal whether or not life exists on those planets in any great quantity.


Artist's depiction of the James Webb Space Telescope (NASA).

The Kepler telescope is confirming what scientists have only been able to speculate up to now; that our galaxy is filled with stars that have planets orbiting them, just like our own solar system.  The wealth of knowledge Kepler is bringing to humanity is astounding.  Hopefully, these discoveries will drive home the point that space based astronomy is an important and vital resource in unlocking the mysteries of our universe.

Monday, January 2, 2012

China's Space Plans

Last week, the Chinese government released a 17 page white paper document entitled, "China's Space Activities in 2011."  The paper is a brief summing up of the last five years in Chinese space activities, and a preview of what to expect in the next five year space program.  While the paper isn't mind blowing in its scope or material, it does touch on some interesting points.

The accomplishments of the Chinese space program have been impressive in the last five years, and the paper focuses on the most noteworthy achievements.  Since 2006, the Long March series of rockets, China's workhorse, has had 67 successful launches, making it one of the world's most reliable launch systems.  In 2007 and 2010, China launched Chang'e-1 and Chang'e-2, respectively, which marked the nation's first serious foray into deep space exploration.  Both spacecraft successfully orbited, mapped, and studied the Moon. In 2008, China successfully launched three men aboard Shenzhou-7, a mission that saw the country's first spacewalk.  And, most recently, China launched its first space lab, Tiangong-1, and successfully remotely docked a Shenzhou spacecraft with the orbiting lab.  The paper also mentions a few scientific accomplishments, like experiments in physics and materials sciences.

Chinese astronaut, Zhai Zhigang, waves to the camera during his 2007 spacewalk (BBC).


The paper goes on to lay out a general plan for China's space program for the next five years.  A continuation of the space lab program, in preparation for a full-fledged space station is highlighted.  This next year will see another unmanned docking with Tiangong-1, as well as one manned mission to the lab.  The Chinese lunar program will move forward as well, with a plan to do a soft landing, followed by a lunar rover, and culminating in a soil return mission.  China will also develop several new rockets in its Long March series, including a "heavy lift" variant which proposes to launch 25 tons into low Earth orbit.


Possible configurations of the proposed Long March 5 family of rockets (Jirka Dlouhy).

One of the surprising things about the document is how much emphasis is put on international cooperation.  Every international space agreement China has entered into is detailed, from commercial deals with the developing world, to multi-national science missions with Europe, to Russia's cooperation with China on their manned program.  This could be a sign that China is opening up more, and by highlighting the work they have already conducted with other nations, they hope to cozy up to bigger space partners (maybe the US?).

Not surprisingly, there are some inconsistencies with what the Chinese government says, and what it does.  The paper highlights China's efforts to mitigate and track space debris.  However, in 2007 the Chinese tested an anti-satellite weapon, destroying one of their own aging weather satellites.  This incident created over 2,300 pieces of trackable space debris.  While this stunt may have demonstrated China's satellite killing ability to the world, it created more space debris than any other single event in history.  Debris from this incident has already threatened the ISS once, and will continue to be a problem for all space faring nations decades to come.

Propaganda aside, China is indeed pushing forward in all aspects of their space program, and this latest document is an interesting glimpse of where China is headed in space.  Let's hope they keep to their commitment of greater international cooperation, an increase in space science, and a reduction in dangerous space debris.

Read the full text of the white paper, here.