Tag Archives: NASA

Orion Oversold?

December 4th is the date set for the first test flight of NASA’s new Orion capsule.  It will be launched into Earth orbit using a Delta IV rocket at about 7:05 AM.  Then, Orion will circle the Earth twice, conduct some test maneuvers, then enter the atmosphere at about 80% of the velocity the capsule would have if it was returning from the Moon.  If the reentry systems work properly, Orion should splash down in the Pacific off the coast of San Diego, California before noon.  Unless it lands like the capsule in “Gravity”, Orion will be bobbing at the surface and picked up by a waiting ship.

NASA has been loudly promoting Orion, claiming that it is the vehicle that will take American astronauts beyond low Earth orbit and to destinations such as the Moon and Mars.  Much ink and many pixels have been used to promote Orion as a truly advanced spacecraft.  But let’s see it for what it is.

I dimly recall back in the early 1970’s there was a proposal to build a larger version of the Apollo-era command module.  The plans were all drawn up for it, then it was decided that there was no need for it.  Orion looks like the resurrection of this project.  Of course, Orion does have some updated technology, such as new heat shield material, far superior computers, nicely decorated interior, and touchscreen panels (like the controls you would find on “Star Trek: The Next Generation” or on an Asgard ship from the “Stargate” franchise, if you prefer).  But don’t be fooled, it is still based on your father’s (or grandfather’s depending on your age) Apollo command module.

Actually, there is something about Orion that is actually inferior to the original Apollo-era vehicle.  The Orion will use a service module that is based on the ESA’s (European Space Agency) Automated Transfer Vehicle (ATV) that has been used to send supplies up to the ISS.  This ATV-derived service module will use solar panels instead of fuel cells to generate electrical power and will certainly have far less powerful engines than the original Apollo-era service module did.

Then, there was a statement made about the Orion by a Russian commentator who pointed out that, for a vessel that is supposed to house a crew for up to three weeks or so, it lacked certain amenities.  While on a short trip to the Moon, that might not be a big deal since the original Apollo astronauts didn’t complain about the lack of a convenience, it could pose a problem for longer trips.

What bothers me is how NASA keeps pushing the idea that Orion will take astronauts to Mars.  It is simply way too small for the job (unless someone manages to develop the technology used to create the sub-light propulsion systems of mainstream science fiction programs).  Even Robert Zubrin (creator of the Mars Direct concept of a reasonably priced program of Mars exploration) and his colleagues and the folks at Mars Direct have put more thought into designing a spacecraft to take people to Mars.

Why has NASA gone so far overboard in promoting Orion?  Probably because that it is about the only idea they have left for manned spaceflight (besides the Space Launch System – SLS – heavy rocket).

Hopefully the test flight of Orion will go well and not wind up exploding, running out of power,  sinking on splashdown, or anything like that.  But do you think that Orion’s “Back to the Future” approach is the way to go or do you think it’s another one of NASA’s ideas that will fall well short of the mark?

What is the Real Cost of Saving Kepler?

Kepler K2 Mission Diagram

Diagram of Kepler’s K2 Mission

In March of 2009, the Kepler mission was launched.  It was placed in an Earth-trailing orbit around the Sun and observed a patch of sky located in the Milky Way near the constellation of Cygnus to look at thousands of stars to detect any dimming that was caused by a planet passing in front of a star.  This mission was by any criterion a great success and racked up an impressive number of discoveries, including the first rocky planets in the habitable zone of a star.

However, in April of 2013, one of the spacecraft’s reaction wheels (powered gyroscopes used to control the pointing of the vehicle) failed.  One had failed earlier, but there were still enough wheels for the mission to continue.  This time was different.  Kepler was placed into a safe mode which allowed it to communicate to Earth.  For the next three months, various strategies were tried to see if the reaction wheel that failed earlier could be restarted.  It was restarted but did not function well.

Then, some on the team had a stroke of brilliance.  After doing the complicated math and computer simulations, they came up with a way to save the mission by using the pressure of solar radiation (a major cause of instability to Kepler) as a means to help keep the spacecraft stable.  NASA liked the idea, known as “K2” (no connection to the extremely dangerous Himalayan mountain of the same designation) and depicted in the above diagram.  So, Kepler was saved, but at what cost?

In terms of dollars and cents, it was a great bargain.  However, when it came to Kepler’s capabilities, it turns out to be an almost Faustian deal.

The great strength of the original Kepler mission was that it kept one well-known section of sky under continuous surveillance.  That way, Kepler would not miss anything that took place.  As a result, Kepler discovered planets of longer periods and was able to observe the three transits required to confirm the discoveries.  The success of this strategy can be seen in the large number of planet discoveries from the mission.

Due to the use of solar radiation pressure as stabilization, Kepler has to be pointed at the ecliptic plane (the plane where the planets of the solar system tend orbit).  That doesn’t sound so bad, but since the Sun appears in the ecliptic plane, Kepler has to move to observe another field about every 83 days so the Sun doesn’t shine into the instrument and burn out the detectors.  Factoring in the time it would take to adjust Kepler each time it moved to one of the eight fields, that yields less than 83 days per field.  So, the concept of continuous surveillance goes right out the window.

Since a “year” for Kepler in its solar orbit is 379 days and only about four and a half fields can be observed in one Kepler “year”, that means quite a bit of time will pass before it returns to a field for further observation.  A lot can happen in that time and a many potential planets will be missed.  Mission scientists naturally downplay this and claim that the increased number of viewing locations will make up for it.  True, there will be some discoveries made from the K2 mission, but they won’t be anywhere near as numerous due to the spotty nature of the observations.  If you are a fan of extrasolar planets, you better get used to most of the new discoveries being hot Jupiters, hot Neptunes, and lava worlds, rather than the more interesting habitable zone planets, because the short duration of observations in each field will favor the planets with really short orbital periods, even with the new policy of requiring only two repeat transits to confirm a planet instead of three.

And this approach of observing lots of area for shorter intervals appears to be the wave of the future in searching for extrasolar planets from space.  If you like the K2 mission, you’ll love the followup mission to Kepler called TESS (Transiting Exoplanet Survey Satellite) which will survey most of the sky while in an eccentric Earth orbit with little time devoted to each field.

You can read the full gory details about K2 here.  Is the new strategy of observing more area in less time worth it for extrasolar planets or should there be a return to more time in less area in the future?