Kepler Mission Options

[HSchirmer]

Look at the light curve. A dark sphere transiting a luminous sphere doesn't fit the data well.

Hmm, I had not thought about it too much before, but... Isn't this 2d data? As in a bright disk and a dark disk, not necessarily 3d spheres?

So, can we resolve the differences in the light curves of a luminous sphere being transited by a circle, a triangle, a square, a hexagon?
If the light curve data turns out to be a match for a 1 x 4 x 9 monolith, this gets really, really interesting.

MOD: And really, REALLY close to breaking Forum rules. This discussion is slipping beyond acceptable Forum subject matter--only warning.

[Mongo]

Possible Trojan planet found?

Characterization of Kepler-91b and the Investigation of a Potential Trojan Companion Using EXONEST

Abstract: Presented here is an independent re-analysis of the Kepler light curve of Kepler-91 (KIC 8219268). Using the EXONEST software package, which provides both Bayesian parameter estimation and Bayesian model testing, we were able to re-confirm the planetary nature of Kepler-91b. In addition to the primary and secondary eclipses of Kepler-91b, a third dimming event appears to occur approximately 60o away (in phase) from the secondary eclipse, leading to the hypothesis that a Trojan planet may be located at the L4 or L5 Lagrange points. Here, we present a comprehensive investigation of four possibilities to explain the observed dimming event using all available photometric data from the Kepler Space Telescope, recently obtained radial velocity measurements, and N-body simulations. We find that the photometric model describing Kepler-91b and a Trojan planet is highly favored over the model involving Kepler-91b alone. However, it predicts an unphysically high temperature for the Trojan companion, leading to the conclusion that the extra dimming event is likely a false-postive.

Given the available data and the models employed, it is not yet possible to come to a conclusion as to the presence of a Trojan partner to Kepler -91b. In favor of the Trojan hypothesis is the fact that the Bayesian evidence of the Jovian+Trojan model is exp(16) times greater than the Jovian model. This hypothesis is still highly probable if one considers a reasonable prior probability reflecting the fact that a Trojan planet has never been observed in the set of 5000 or so exoplanet candidates. It is also remarkable that the model selected the appropriate relative phase for the Trojan companion. While the probability of this occurring is not overwhelming, it is on the order of 1/36. However, this correct positioning of a Trojan occurred at the expense of having the secondary transit be deeper than the primary, which leads to the model ascribing an unphysically high day-side temperature to the Trojan, which clearly makes the Trojan hypothesis suspect. In addition, unusual features, such as the odd/even phase differences in the light curve and the mideclipse brightening, which occurs not only during the Jovian eclipses, but also during hypothetical Trojan eclipses may be mimicking a Trojan-like signal. At this stage, given the available data and the models employed, it is impossible to say anything definitive concerning the presence of a Trojan companion.

[JRehling]

That possible Trojan, associated with Kepler-91b, is a very weird case. The star is a red giant, but the planet is orbiting very close to it (6 day period). The quirk: The orbit is inclined 68° to the line of sight, but we still observe transits because the star is so large and the planet is so close. So, the usual paradigm of the planet's image slicing through the star's image in a straight-line chord is not a good approximation here, and the image it presents to us (though it cannot be resolved as such) is more like the ground track of a satellite orbiting the Earth in Low Earth Orbit, taking a curved path across the star's disc. This creates deviations from the usual case as the planet's entire transit may occur near the star's limb, where limb darkening is significant, so the whole light curve is apt to be unusual.

All told, if we see something strange in this case, it's a good puzzle to work out, and I'm not sure the correct interpretation will easily be had, as this paper indicates. I imagine we have a lot to learn about red giants and exoplanet research can actually further that.

[Paolo]

Kepler has also provided some badly needed, new data on a poorly known (and for some reason, one of my favorite) solar system body:
Nereid from space: Rotation, size and shape analysis from Kepler/K2, Herschel and Spitzer observations

In this paper we present an analysis of Kepler K2 mission Campaign 3 observations of the irregular Neptune satellite, Nereid. We determined a rotation period of P=11.594(+/-)0.017 h and amplitude of dm=0.0328(+/-)00018, confirming previous short rotation periods obtained in ground based observations. The similarities of light curve amplitudes between 2001 and 2015 show that Nereid is in a low-amplitude rotation state nowadays and it could have been in a high-amplitude rotation state in the mid 1960's. Another high-amplitude period is expected in about 30 years. Based on the light curve amplitudes observed in the last 15 years we could constrain the shape of Nereid and obtained a maximum a:c axis ratio of 1.3:1. This excludes the previously suggested very elongated shape of a:c=1.9:1 and clearly shows that Nereid's spin axis cannot be in forced precession due to tidal forces. Thermal emission data from the Spitzer Space Telescope and the Herschel Space Observatory indicate that Nereid's shape is actually close to the a:c axis ratio limit of 1.3:1 we obtained, and it has a very rough, highly cratered surface

[nprev]

MOD NOTE: Moved posts about KIC 8462852 to a dedicated topic to free up the Kepler thread for other mission findings.

[nprev]

The Kepler team has declared a spacecraft emergency, thus obtaining priority DSN access. Anomaly occurred between 4 and 7 Apr.

[antipode]

Another reaction wheel perhaps?

If so, that will just about be it I guess...

P

[Mongo]

Mission Manager Update: Kepler Recovered from Emergency and Stable

Mission operations engineers have successfully recovered the Kepler spacecraft from Emergency Mode (EM). On Sunday morning, the spacecraft reached a stable state with the communication antenna pointed toward Earth, enabling telemetry and historical event data to be downloaded to the ground. The spacecraft is operating in its lowest fuel-burn mode.

The mission has cancelled the spacecraft emergency, returning the Deep Space Network ground communications to normal scheduling.

Once data is on the ground, the team will thoroughly assess all on board systems to ensure the spacecraft is healthy enough to return to science mode and begin the K2 mission's microlensing observing campaign, called Campaign 9. This checkout is anticipated to continue through the week.

Earth-based observatories participating in Campaign 9 will continue to make observations as Kepler's health check continues. The K2 observing opportunity for Campaign 9 will end on July 1, when the galactic center is no longer in view from the vantage point of the spacecraft.

K2's previous science campaign concluded on March 23. After data was downlinked to the ground, the spacecraft was placed in what is termed Point Rest State (PRS). While in PRS, the spacecraft antenna is pointed toward Earth and it operates in a fuel-efficient mode, with the reaction wheels at rest.

The Emergency Mode began approximately 14 hours before the planned maneuver to orient the spacecraft toward the center of the Milky Way for Campaign 9. The team has therefore ruled out the maneuver and the reaction wheels as possible causes of the EM event. An investigation into what caused the event will be pursued in parallel, with a priority on returning the spacecraft to science operations.

The anomalous EM event is the first that the Kepler spacecraft has encountered during its seven years in space. Mission operations at NASA's Ames Research Center in California's Silicon Valley, Ball Aerospace and the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder remain vigilant.

It was the quick response and determination of the engineers throughout the weekend that led to the recovery. We are deeply appreciative of their efforts, and for the outpouring of support from the mission's fans and followers from around the world. We also recognize the tremendous support from NASA’s Deep Space Network, managed by the Jet Propulsion Laboratory in Pasadena, California, and to NASA’s other missions that surrendered their scheduled telemetry links in order to provide us with the resources needed to protect the Kepler spacecraft.

Updates will be provided as information warrants.

[PaulH51]

Mission Manager Update: Kepler Recovered from Emergency and Stable

Spotted this update:
Mission Manager Update: Kepler Remains Stable as Health Check Continues April 16 2016: LINK

The Kepler spacecraft remains stable as the process of returning it to science continues. The cause of the anomaly, first reported on April 8, remains under investigation.

Since Sunday morning the spacecraft has remained safely "parked" in a stable pointed configuration called Point Rest State. In this state, fuel usage remains low and the communication link to Earth is good. As of Tuesday, mission operations engineers had downlinked all the necessary data from Kepler to triage the situation and plan the steps toward recovery.

The recovery to science began with a thorough assessment of the data, which took a couple days, after which the team had learned all they could about the state of the spacecraft from the data. It was then time to turn back on and test the components deemed low-risk to spacecraft health. Testing begins on the Kepler spacecraft simulator at the flight planning center at Ball Aerospace in Boulder, Colorado. With the ground-based simulation a success, we were ready to conduct the tests on Kepler, 75 million miles away. The engineers sent the instructions, along with commands for the spacecraft to protect itself and enter a safe operating mode if there was a problem, and waited for the spacecraft to report back.

The spacecraft returned a response that is the equivalent of 'so far, so good.' It did not experience any faults from switching on the components, and all the data suggest the components are working normally. The spacecraft is another step closer to returning to scientific observations for the K2 mission.

The photometer – Kepler’s camera – and the solid state recorder are powered on. The subsystem interface box, which is the interface between the spacecraft sensors and the main computer, was only briefly powered on for an initial assessment, but should be back online early next week. The team will continue recovering the components, as they are deemed safe and low-risk to the spacecraft.

Over the weekend, NASA's Deep Space Network (DSN) will remain in contact with the spacecraft while the team gets some much-needed rest. To watch the worldwide array of antennae communicate with the spacecraft, tune-in to DSN Now.

The recovery started slowly and carefully, as we initially merely tried to understand the situation and recover the systems least likely to have been the cause. Over the last day and a half, we’ve begun to turn the corner, by powering on more suspect components. With just one more to go, I expect that we will soon be on the home stretch and picking up speed towards returning to normal science operations.

Updates will be provided as information warrants.

[PaulH51]

Good News:
Mission Manager Update: Kepler Recovered and Returned to the K2 Mission (April 22, 2016)
Link
Extract

The cause of the anomaly, first reported on April 8, remains under investigation. The nature of the problem has indications of a transient event, which triggered a barrage of false alarms that eventually overwhelmed the system, placing Kepler in Emergency Mode. Power-cycling the onboard computers and subsystems appears to have cleared the problem. We’ve returned to science data collection while the investigation proceeds.

[nprev]

Hmm. CR hit somewhere in the processor, perhaps? In any case, excellent news indeed. Thanks!

[PaulH51]

Hmm. CR hit somewhere in the processor, perhaps? In any case, excellent news indeed. Thanks!

Looks like a good call on the CR hit....

Another update on the recent incident Release dated May 4th 2016

Mission Manager Q&A: Recovering The Kepler Spacecraft To Hunt For Exoplanets Again Link

[Explorer1]

Telecon on new discoveries in 10 minutes:
http://www.nasa.gov/news/media/newsaudio/index.html

Starting now... slides up here: http://www.nasa.gov/feature/ames/kepler/br...materials160510

1284 newly validated!

[Steve G]

When are they going to start giving official names to all of these planets?

[JRehling]

Most of these will never* be revisited again, except as entities in larger statistical studies, so we probably don't need to hand out any names for the vast majority of them.

* = Not actually "never" but anytime soon.