More Insight on How NASA Might Revive the Kepler Space Telescope

The future of NASA’s Kepler space telescope mission is in doubt, NASA announced yesterday, as it suffered a failure of a second reaction wheel, losing its ability to precisely point to look for planets orbiting other stars. Reaction wheels enable the spacecraft to aim in different directions without firing thrusters, and the spacecraft needs at least three of the four wheels working to provide the ability to point precisely enough to continue the mission.

But, as we pointed out in our article yesterday, the Kepler team said there are still possibilities of keeping the spacecraft in working order, or perhaps even finding other opportunities for different science for Kepler, something that doesn’t require such precise pointing abilities.

“We’re not ready to call the mission down and out just yet,” said John Grunsfeld, NASA’s associate administrator for the Science Mission Directorate, “but by any measure it’s been a spectacular mission.”

Space expert Scott Hubbard has provided additional insight on the possible ways that NASA could bring the spacecraft back online, and what planet hunters will do next if that’s not possible. Hubbard is a consulting professor of aeronautics and astronautics at Stanford’s School of Engineering, and served as director of NASA Ames Research Center during much of the building phase of the Kepler space telescope. He also worked on the project alongside William Borucki, the Kepler science principal investigator at Ames and the driving force behind the effort, for the decades leading up to formal approval of the mission.

Standford University provided this conversation Hubbard:

Q: How big of a loss will it be if the Kepler space telescope can’t be repaired?

Hubbard: The science returns of the Kepler mission have been staggering and have changed our view of the universe, in that we now think there are planets just about everywhere.

It will be very sad if it can’t go on any longer, but the taxpayers did get their money’s worth. Kepler has, so far, detected more than 2,700 candidate exoplanets orbiting distant stars, including many Earth-size planets that are within their star’s habitable zone, where water could exist in liquid form.

Kepler has done what the program managers said it would do, and that is to give us an inventory of extrasolar planets. It completed its primary observation phase, and had entered its extended science phase. We’re already in the gravy train period – there’s still a year and a half’s worth of data in the pipeline that scientists will analyze to identify other candidate planets, and there will continue to be Kepler science discoveries for quite some time.

Kepler space telescope's field of view. Credit: NASA
Kepler space telescope’s field of view. Credit: NASA

Q: How might NASA engineers go about getting Kepler functional again?

Hubbard: There are two possible ways to salvage the spacecraft that I’m aware of. One is that they could try turning back on the reaction wheel that they shut off a year ago. It was putting metal on metal, and the friction was interfering with its operation, so you could see if the lubricant that is in there, having sat quietly, has redistributed itself, and maybe it will work.

The other scheme, and this has never been tried, involves using thrusters and the solar pressure exerted on the solar panels to try and act as a third reaction wheel and provide additional pointing stability. I haven’t investigated it, but my impression is that it would require sending a lot more operational commands to the spacecraft.

Q: If neither of these options works, Kepler is still an amazing space instrument. Could it conduct other types of experiments?

Hubbard: People have asked about using it to find near-Earth objects, or asteroids. Kepler carries a photometer, not a camera, that looks at the brightness of stars, and so its optics deliberately defocus light from stars to create a nice spread of light on the detector, which is not ideal for spotting asteroids.

Whether or not it could function as a detector for asteroids is something that would have to be studied, but since it wasn’t built as a camera, I would say that I’m skeptical. That said, certainly between Ames Research Center and the Jet Propulsion Laboratory, they’ve got the best people in the world working on it.

Visualization of Kepler's planet candidates shown in transit with their parent stars. Credit: Jason Rowe/Kepler Mission/NASA
Visualization of Kepler’s planet candidates shown in transit with their parent stars. Credit: Jason Rowe/Kepler Mission/NASA

Q: What’s next for exoplanet hunters?

Hubbard: As I said earlier, there is still a year and a half’s worth of data in the pipeline to analyze to identify candidate planets, so there are still discoveries to be made.

It’s important to make clear, though, that in the original queue of missions aimed at finding life elsewhere, a mission like Kepler was a survey mission to establish the statistical frequency of whether these planets are rare or common. It lived the length of its prime mission, and was extremely successful during that time at achieving this goal. It has paved the way for additional missions, such as TESS – Transiting Exoplanet Survey Satellite – and TPF – Terrestrial Planet Finder – which will continue the search for Earth-like exoplanets in the near future.

Using the Theory of Relativity and BEER to Find Exoplanets

A new method of detecting alien worlds is full of awesome, as it combines Einstein’s Theory of Relativity along with BEER. No, not the weekend beverage of choice, but the relativistic BEaming, Ellipsoidal, and Reflection/emission modulations algorithm. This new way of finding exoplanets was developed by Professor Tsevi Mazeh and his student, Simchon Faigler, at Tel Aviv University, Israel, and it has been used for the first time to find a distant exoplanet, Kepler-76b, informally named Einstein’s planet.

“This is the first time that this aspect of Einstein’s theory of relativity has been used to discover a planet,” said Mazeh.

The two most-most used and prolific techniques for finding exoplanets are radial velocity (looking for wobbling stars) and transits (looking for dimming stars).

The new method looks for three small effects that occur simultaneously as a planet orbits the star. A “beaming” effect causes the star to brighten as it moves toward us, tugged by the planet, and dim as it moves away. The brightening results from photons “piling up” in energy, as well as light getting focused in the direction of the star’s motion due to relativistic effects.

The team also looked for signs that the star was stretched into a football shape by gravitational tides from the orbiting planet. The star would appear brighter when we observe the “football” from the side, due to more visible surface area, and fainter when viewed end-on. The third small effect is due to starlight reflected by the planet itself.

“This was only possible because of the exquisite data NASA is collecting with the Kepler spacecraft,” said Faigler.

This graphic shows Kepler-76b's orbit around a yellow-white, type F star located 2,000 light-years from Earth in the constellation Cygnus. Although Kepler-76b was identified using the BEER effect (see above), it was later found to exhibit a grazing transit, crossing the edge of the star's face as seen from Earth. Credit: Dood Evan.
This graphic shows Kepler-76b’s orbit around a yellow-white, type F star located 2,000 light-years from Earth in the constellation Cygnus. Although Kepler-76b was identified using the BEER effect (see above), it was later found to exhibit a grazing transit, crossing the edge of the star’s face as seen from Earth.
Credit: Dood Evan.

Although scientists say this new method can’t find Earth-sized worlds using current technology, it offers astronomers a unique discovery opportunity. Unlike radial velocity searches, it doesn’t require high-precision spectra. Unlike transits, it doesn’t require a precise alignment of planet and star as seen from Earth.

“Each planet-hunting technique has its strengths and weaknesses. And each novel technique we add to the arsenal allows us to probe planets in new regimes,” said Avi Loeb from the Harvard-Smithsonian Center for Astrophysics, who first proposed the idea of this planet-hunting method back in 2003.

Kepler-76b is a “hot Jupiter” that orbits its star every 1.5 days. Its diameter is about 25 percent larger than Jupiter and it weighs twice as much. It orbits a type F star located about 2,000 light-years from Earth in the constellation Cygnus.

The planet is tidally locked to its star, always showing the same face to it, just as the Moon is tidally locked to Earth. As a result, Kepler-76b broils at a temperature of about 3,600 degrees Fahrenheit.

Interestingly, the team found strong evidence that the planet has extremely fast jet-stream winds that carry the heat around it. As a result, the hottest point on Kepler-76b isn’t the substellar point (“high noon”) but a location offset by about 10,000 miles. This effect has only been observed once before, on HD 189733b, and only in infrared light with the Spitzer Space Telescope. This is the first time optical observations have shown evidence of alien jet stream winds at work.

The planet has been confirmed using radial velocity observations gathered by the TRES spectrograph at Whipple Observatory in Arizona, and by Lev Tal-Or (Tel Aviv University) using the SOPHIE spectrograph at the Haute-Provence Observatory in France. A closer look at the Kepler data also showed that the planet transits its star, providing additional confirmation.

The paper announcing this discovery has been accepted for publication in The Astrophysical Journal and is available on arXiv.

Source: CfA

Clouds part for Transit of Venus from Princeton University

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Despite a horrendous weather forecast, the clouds parted – at least partially – just in the nick of time for a massive crowd of astronomy and space enthusiasts gathered at Princeton University to see for themselves the dramatic start of the Transit of Venus shortly after 6 p.m. EDT as it arrived at and crossed the limb of the Sun.

And what a glorious view it was for the well over 500 kids, teenagers and adults who descended on the campus of Princeton University in Princeton, New Jersey for a viewing event jointly organized by the Astrophysics Dept and the Amateur Astronomers Association of Princeton (AAAP), the local astronomy club to which I belong.

See Transit of Venus astrophotos snapped from Princeton, above and below by Astrophotographer and Prof. Bob Vanderbei of Princeton U and a AAAP club member.

Transit of Venus snapped from Princeton University - full sized image
This photo was taken with a Questar telescope at 6:26 p.m. on June 5, 2012 - it’s a stack of eight - 2 second images. Stacking essentially eliminates the clouds. Hundreds attended the Transit of Venus observing event organized jointly by Princeton University Astrophysics Dept and telescopes provided by the Amateur Astronomers Association of Princeton (AAAP), local astronomy club. Credit: Robert Vanderbei

It was gratifying to see so many children and whole families come out at dinner time to witness this ultra rare celestial event with their own eyes – almost certainly a last-in-a-lifetime experience that won’t occur again for another 105 years until 2117. The crowd gathered on the roof of Princeton’s Engineering Dept. parking deck – see photos

Excited crowd witnesses last-in-a-lifetime Transit of Venus from campus rooftop on Princeton University. Onlookers gathered to view the rare Transit of Venus event using solar telescopes provided by the Amateur Astronomers Association of Princeton (AAAP) and solar glasses provided by NASA and lectures from Princeton University Astrophysics Dept.
Credit: Ken Kremer

For the next two and a half hours until sunset at around 8:30 p.m. EDT, we enjoyed spectacular glimpses as Venus slowly and methodically moved across the northern face of the sun as the racing clouds came and went on numerous occasions, delighting everyone up to the very end when Venus was a bit more than a third of the way through the solar transit.

Indeed the flittering clouds passing by in front of Venus and the Sun’s active disk made for an especially eerie, otherworldly and constantly changing scene for all who observed through about a dozen AAAP provided telescopes properly outfitted with special solar filters for safely viewing the sun.

Kids of all ages enjoy the Transit of Venus from a rooftop at Princeton University. Solar telescopes provided by the Amateur Astronomers Association of Princeton (AAAP), solar glasses provided by NASA and lectures from Princeton University Astrophysics Dept. Credit: Ken Kremer

As part of this public outreach program, NASA also sent me special solar glasses to hand out as a safe and alternative way to directly view the sun during all solar eclipses and transits through your very own eyes – but not optical aids such as cameras or telescopes.

Transit of Venus snapped from Princeton University - quarter sized image
This photo was taken with a Questar telescope at 6:26 p.m. on June 5, 2012 - it’s a stack of eight - 2 second images. Credit: Robert Vanderbei

Altogether the Transit lasted 6 hours and 40 minutes for those in the prime viewing locations such as Hawaii – from where NASA was streaming a live Transit of Venus webcast.

You should NEVER look directly at the sun through any telescopes or binoculars not equipped with special eye protection – because that can result in severe eye injury or permanent blindness!

We in Princeton were quite lucky to observe anything because other astro friends and fans in nearby areas such as Philadelphia, PA and Brooklyn, NY reported seeing absolutely nothing for this last-in-a-lifetime celestial event.

Transit of Venus enthusiasts view the solar transit from Princeton University rooftop using special solar glasses provided by NASA. Credit: Ken Kremer

Princeton’s Astrophysics Department organized a series of lectures prior to the observing sessions about the Transit of Venus and how NASA’s Kepler Space Telescope currently uses the transit method to detect and discover well over a thousand exoplanet and planet candidates – a few of which are the size of Earth and even as small as Mars, the Red Planet.

NASA’s Curiosity rover is currently speeding towards Mars for an August 6 landing in search of signs of life. Astronomers goal with Kepler’s transit detection method is to search for Earth-sized planets in the habitable zone that could potentially harbor life !

So, NASA and astronomers worldwide are using the Transit of Venus in a scientifically valuable way – beyond mere enjoyment – to help refine their planet hunting techniques.

Doing an outreach program for NASA, science writer Dr Ken Kremer distributes special glasses to view the transit of Venus across the sun during a viewing session on the top level of a parking garage at the E-quad at Princeton University to see the transit of Venus across the sun on Tuesday evening, June 5, 2012. Michael Mancuso/The Times

Historically, scientists used the Transit of Venus over the past few centuries to help determine the size of our Solar System.

See more event photos from the local daily – The Trenton Times – here

And those who stayed late after sunset – and while the Transit of Venus was still visibly ongoing elsewhere – were treated to an extra astronomical bonus – at 10:07 p.m. EDT the International Space Station (ISS) coincidentally flew overhead and was visible between more break in the clouds.

The International Space Station (ISS) flew over Princeton University at 10:07 p.m. on June 5 after the sun had set but while the Transit of Venus was still in progress. Credit: Ken Kremer
Transit Of Venus image from Hinode Spacecraft. Click to enlarge. Credit: JAXA/NASA/Lockheed Martin/enhanced by Marco Di Lorenzo

Of course clouds are no issue if you’re watching the Transit of Venus from the ISS or the Hinode spacecraft. See this Hinode Transit image published on APOD on June 9 and enhanced by Marco Di Lorenzo.

This week, local NY & NJ residents also had another extra special space treat – the chance to see another last-in-a-lifetime celestial event: The Transit of Space Shuttle Enterprise across the Manhattan Skyline on a seagoing voyage to her permanent new home at the Intrepid Sea, Air and Space Museum.

Ken Kremer

Kepler Spacecraft Back in Action After Computer Glitch

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NASA’s Kepler spacecraft is back in planet-hunting action after a computer malfunction put it into “safe mode” for 144 hours (six days.) The anomaly occurred on March 14, 2011 immediately after the spacecraft issued a network interface card (NIC) reset command to start a computer program update. During the reset, the NIC sent invalid reaction wheel data to the flight software, which caused the spacecraft to enter the self-protecting safe mode. The NIC is the interfaces between the spacecraft’s flight software, attitude determination, and its control subsystems and sensors. Mission managers said an anomaly response team will continue to evaluate the spacecraft data to determine the cause of the safe mode event.

A safe mode is a measure the spacecraft takes to protect itself when something unexpected occurs. Kepler mission managers described what happens during a safe mode event:

“During safe mode, the spacecraft points the solar panels directly at the sun and begins to slowly rotate along a sun-aligned axis. This safe mode orientation provides the vehicle with the maximum power and limits the buildup of momentum from solar wind. The spacecraft also swapped to its backup subsystem interface box (SIB), an electronics component that provides thermal and power distribution control to all spacecraft subsystems, and powered off the photometer, the instrument used to measure light intensity to detect planets. This is a normal procedure when the spacecraft enters safe mode.”

Kepler spacecraft returned to science data collection at 2:45 p.m. EDT Sunday, March 20, 2011.

Kepler launched in 2009 to look for alien worlds, hoping to find one like Earth in the just-right “Goldilocks Zone” around another star. So far, Kepler has discovered 1,235 possible planets, with 54 of those candidates in that potential habitable zone where liquid water could exist on a planet’s surface. Further study is needed to see if any of these planets have the potential to harbor life.

But given how many potential habitable planets were found in just one area of the sky, astronomers have estimated that our Milky Way galaxy could hold as many as 50 billion alien planets, with 2 billion of those being about the size of Earth.

Stay tuned!

Source: Kepler