WFIRST Passes its Preliminary Design Review

The telescope for a major NASA astrophysics mission has passed a key review that the agency says keeps it on track for launch in the mid-2020s despite uncertainty about its funding for 2020 and beyond.

NASA announced Aug. 28 that the telescope assembly for the Wide Field Infrared Survey Telescope (WFIRST) mission passed its preliminary design review (PDR), allowing the project to continue work to finalize its design.

WFIRST, scheduled for launch in the mid-2020s, is NASA’s next flagship astrophysics mission after the James Webb Space Telescope. The mission will use a 2.4-meter mirror provided to NASA by the National Reconnaissance Office. That mirror is currently being modified by L3 Harris Technologies for use on WFIRST.

The telescope will later be equipped with both a wide-field imager instrument and a coronagraph, which blocks light from stars to allow direct imaging of planets and dust disks orbiting them. Both will have their own preliminary design reviews, along with one for the entire mission.

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WISE & NEOWISE Cannot Find Planet Nine

A 3pi Search for Planet Nine at 3.4 microns with WISE and NEOWISE

Authors:

Meisner et al

Abstract:
The recent 'Planet Nine' hypothesis has led to many observational and archival searches for this giant planet proposed to orbit the Sun at hundreds of astronomical units. While trans-Neptunian object searches are typically conducted in the optical, models suggest Planet Nine could be self-luminous and potentially bright enough at ~3-5 microns to be detected by the Wide-field Infrared Survey Explorer (WISE). We have previously demonstrated a Planet Nine search methodology based on time-resolved WISE coadds, allowing us to detect moving objects much fainter than would be possible using single-frame extractions. In the present work, we extend our 3.4 micron (W1) search to cover more than three quarters of the sky and incorporate four years of WISE observations spanning a seven year time period. This represents the deepest and widest-area WISE search for Planet Nine to date. We characterize the spatial variation of our survey's sensitivity and rule out the presence of Planet Nine in the parameter space searched at W1 less than 16.7 in high Galactic latitude regions (90% completeness).

Search of ALLWise Data Does NOT Find Planet Nine

The Hunt for Planet Nine: Atmosphere, Spectra, Evolution, and Detectability

Authors:

Fortney et al

Abstract:

We investigate the physical characteristics of the Solar System's proposed Planet Nine using modeling tools with a strong heritage in studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic Teff, from ~35-50 K for masses of 5-20 M_Earth. Possible planetary radii could readily span from 3 to 6 R_Earth depending on the mass fraction of any H/He envelope. We model the atmospheric temperature structure and spectra. Given its cold temperature, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like expectations. We find the atmosphere is strongly depleted in molecular absorption at visible wavelengths, suggesting a Rayleigh scattering atmosphere with a high geometric albedo of 0.75. We highlight two diagnostics for the atmosphere's temperature structure, the first being the value of the methane mixing ratio above the methane cloud. The second is the wavelength at which cloud scattering can be seen, which yields the cloud-top pressure. Surface reflection may be seen if the atmosphere is thin. Due to collision-induced opacity of H2 in the infrared, the planet would be extremely blue (instead of red) in the shortest wavelength WISE colors if methane is depleted, and would, in some cases, exist on the verge of detectability by WISE. For a range of models, thermal fluxes from ~3-5 microns are ~20 orders of magnitude larger than blackbody expectations. We report a search of the AllWISE Source Catalog for Planet Nine, but find no detection.

China is Supposedly Launching Hubble Telescope Competitor Near Its Space Station in the Future

China is to launch an “optical module” along with the under-construction space station, said Zhang Yulin, Deputy to the National People’s Congress and Deputy Minister of Central Military Commission Equipment Development Department, on March 7, 2016. The “optical module” is similar to Hubble Space Telescope, but the field of view is 300 times that of Hubble.

The module would maintain a certain distance to orbit with the space station. When suffers malfunction or needs maintenance, it will dock to the space station and be operated by astronauts, Zhang said. This will solve the problem Hubble has encountered, when NASA had to send up astronauts particularly to repair it. This special design of China’s space station makes in-orbit maintenance possible, and can thus bring the numerous defunct satellites to life, Zhang said.

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NASA Kicking off WFIRST Space Telescope in February

NASA’s next flagship astronomy mission after the James Webb Space Telescope will become a formal project in February thanks to increased funding and direction from Congress, even as the agency looks to make cuts elsewhere in its astrophysics program.

Paul Hertz, director of NASA’s astrophysics division, told astronomers attending the 227th Meeting of the American Astronomical Society here Jan. 4 that the Wide Field Infrared Survey Telescope (WFIRST) will enter its “formulation phase,” the beginning of NASA’s project management process, in February after the proposed space telescope passed a mission concept review in December.

That decision also comes after the passage of the fiscal year 2016 omnibus spending bill in December that provided $90 million for WFIRST, far above NASA’s request of $14 million. The report accompanying the bill adopted language approved by Senate appropriators in June directing NASA to move WFIRST into the formulation phase by early 2016.

The increase is not the first time Congress has added funding for WFIRST. In fiscal year 2015, NASA requested $14 million but Congress appropriated $50 million. In 2014, Congress provided $56 million for WFIRST.

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James Webb Space Telescope Begins Mirror Installation

NASA’s James Webb Space Telescope (JWST) – the successor to the Hubble Space Telescope – has hit the final assembly phase milestone via the installation of the first of 18 mirrors on the spacecraft’s backbone structure. All 18 segments are expected to be installed by early next year as JWST prepares for launch in 2018 via an Ariane 5 rocket.

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Observing the Icy Moons of the Outer Solar System With the James Webb Space Telescope

Observing Outer Planet Satellites (except Titan) with JWST: Science Justification and Observational Requirements

Authors:

Keszthelyi et al

Abstract:

The James Webb Space Telescope (JWST) will allow observations with a unique combination of spectral, spatial, and temporal resolution for the study of outer planet satellites within our Solar System. We highlight the infrared spectroscopy of icy moons and temporal changes on geologically active satellites as two particularly valuable avenues of scientific inquiry. While some care must be taken to avoid saturation issues, JWST has observation modes that should provide excellent infrared data for such studies.

Using the James Webb Space Telescope to Study Titan

Titan Science with the James Webb Space Telescope (JWST)

Authors:

Nixon et al

Abstract:

The James Webb Space Telescope (JWST), scheduled for launch in 2018, is the successor to the Hubble Space Telescope (HST) but with a significantly larger aperture (6.5 m) and advanced instrumentation focusing on infrared science (0.6-28.0 μm ). In this paper we examine the potential for scientific investigation of Titan using JWST, primarily with three of the four instruments: NIRSpec, NIRCam and MIRI, noting that science with NIRISS will be complementary. Five core scientific themes are identified: (i) surface (ii) tropospheric clouds (iii) tropospheric gases (iv) stratospheric composition and (v) stratospheric hazes. We discuss each theme in depth, including the scientific purpose, capabilities and limitations of the instrument suite, and suggested observing schemes. We pay particular attention to saturation, which is a problem for all three instruments, but may be alleviated for NIRCam through use of selecting small sub-arrays of the detectors - sufficient to encompass Titan, but with significantly faster read-out times. We find that JWST has very significant potential for advancing Titan science, with a spectral resolution exceeding the Cassini instrument suite at near-infrared wavelengths, and a spatial resolution exceeding HST at the same wavelengths. In particular, JWST will be valuable for time-domain monitoring of Titan, given a five to ten year expected lifetime for the observatory, for example monitoring the seasonal appearance of clouds. JWST observations in the post-Cassini period will complement those of other large facilities such as HST, ALMA, SOFIA and next-generation ground-based telescopes (TMT, GMT, EELT).

SETI Talks: Kepler's K2 Mission

NASA may Request Money in 2017 Budget to Begin Work to use ex NRO FIA Telescopes

NASA is considering requesting money in next year's budget to eventually start using two space telescopes it received from the United States' spy satellite agency, a senior official told Space.com.

NASA received the telescopes from the National Reconnaissance Office (NRO) in 2012. They have the same resolution as the agency's famous Hubble Space Telescope, but a field of view 200 times wider.

The telescopes are being eyed for use in a potential space mission called WFIRST-AFTA (the Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets), which could launch as early as 2024 if it gets the final go-ahead. WFIRST-AFTA's science goals include learning more about the mysterious dark energy that is accelerating the expansion of the universe.

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Herschel Looks at Titan's Stratosphere

Herschel/PACS spectroscopy of trace gases of the stratosphere of Titan

Authors:

Rengel et al

Abstract:

Aims:

We investigate the composition of Titan's stratosphere from new medium-resolution far-infrared observations performed with the full range of Herschel's Photodetector Array Camera and Spectrometer (PACS) (51-220 μm at a resolution λ/Δλ ranging from 950 to 5500 depending on wavelength and grating order).

Methods:

Using PACS, we obtained the spectral emission of several features of the Titan's stratosphere. We used a line-by-line radiative transfer code and the least-squares fitting technique to infer the abundances of the trace constituents.

Results:

Numerous spectral features attributable to CH4, CO, HCN, and H2O are present. From the flux density spectrum measured and by a detailed comparison with synthetic spectra, we constrain the stratospheric abundance of CH4, which is assumed to be constant with altitude, to be 1.29 ± 0.03%. Similarly, we constrain the abundance of CO to be 50 ± 2 ppm, and the HCN vertical distribution consistent with an increase from 40 ppb at ∼100 km to 4 ppm at ∼200 km, which is an altitude region where the HCN signatures are sensitive. Measurements of three H2O rotational lines confirm the H2O distribution profile recently obtained with Herschel. Furthermore, we determine the isotopic ratios 12C/13C in CO and HCN to be 124 ± 58, and 66 ± 35, respectively. Comparisons between our results and the values derived with other instruments show that our results are consistent with the vertical distributions and isotopic ratios in previous studies, except for the HCN distribution obtained with Cassini/CIRS, which does not agree with the PACS lines at the 1-sigma confidence interval.

Centaur Chiron, Haumea & Another Kuiper Belt Object Observed in the Ultraviolet by Hubble Space Telescope

FIRST ULTRAVIOLET REFLECTANCE MEASUREMENTS OF SEVERAL KUIPER BELT OBJECTS, KUIPER BELT OBJECT SATELLITES, AND NEW ULTRAVIOLET MEASUREMENTS OF A CENTAUR

Authors:

Stern et al

Abstract:

We observed the 2600-3200 Å (hereafter, mid-UV) reflectance of two Kuiper Belt Objects (KBOs), two KBO satellites, and a Centaur, using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS). Other than measurements of the Pluto system, these constitute the first UV measurements obtained of KBOs, and KBO satellites, and new HST UV measurements of the Centaur 2060 Chiron. We find significant differences among these objects, constrain the sizes and densities of Haumea's satellites, and report the detection of a possible spectral absorption band in Haumea's spectrum near 3050 Å. Comparisons of these objects to previously published UV reflectance measurements of Pluto and Charon are also made here.

A Survey of the Kuiper Belt by Hershel & Spitzer

"TNOs are Cool": A survey of the trans-Neptunian region X. Analysis of classical Kuiper belt objects from Herschel and Spitzer observations

Authors:

Vilenius et al

Abstract:

The classical Kuiper belt contains objects both from a low-inclination, presumably primordial, distribution and from a high-inclination dynamically excited population. Based on a sample of classical TNOs with observations at thermal wavelengths we determine radiometric sizes, geometric albedos and thermal beaming factors as well as study sample properties of dynamically hot and cold classicals. Observations near the thermal peak of TNOs using infra-red space telescopes are combined with optical magnitudes using the radiometric technique with near-Earth asteroid thermal model (NEATM). We have determined three-band flux densities from Herschel/PACS observations at 70.0, 100.0 and 160.0 μm and Spitzer/MIPS at 23.68 and 71.42 μm when available. We have analysed 18 classical TNOs with previously unpublished data and re-analysed previously published targets with updated data reduction to determine their sizes and geometric albedos as well as beaming factors when data quality allows. We have combined these samples with classical TNOs with radiometric results in the literature for the analysis of sample properties of a total of 44 objects. We find a median geometric albedo for cold classical TNOs of 0.14 and for dynamically hot classical TNOs, excluding the Haumea family and dwarf planets, 0.085. We have determined the bulk densities of Borasisi-Pabu (2.1 g/cm^3), Varda-Ilmare (1.25 g/cm^3) and 2001 QC298 (1.14 g/cm^3) as well as updated previous density estimates of four targets. We have determined the slope parameter of the debiased cumulative size distribution of dynamically hot classical TNOs as q=2.3 +- 0.1 in the diameter range 100

WFIRST Could Detect Kuiper Objects as Small as 7.5 km Diameter

WFIRST Ultra-Precise Astrometry I: Kuiper Belt Objects

Author:

Gould

Abstract:

I show that the WFIRST microlensing survey will enable detection and precision orbit determination of Kuiper Belt Objects (KBOs) down to H_vega=28.2 over an effective area of about 17 square deg. Typical fractional period errors will be ~1.5% X 10^{0.4(H-28.2)} with similar errors in other parameters for roughly 5000 KBOs. Binary companions to detected KBOs can be detected to even fainter limits, H_vega=29, corresponding to R~31 and effective diameters D~7.5 km. This will provide an unprecedented probe of orbital resonance and KBO mass measurements.

WFIRST Telescope Using ex NRO Hardware Greatly Increases Science...and Financial Risk

The opportunity to increase the aperture and resolution on NASA’s planned Wide-Field Infrared Survey Telescope (WFIRST) would significantly expand the scientific capabilities of the mission, but the risk of cost growth is significantly higher than for NASA’s original design, says a new report from the National Research Council.

WFIRST was ranked the top-priority large space mission in the National Research Council’s 2010 decadal survey of astronomy and astrophysics research. WFIRST would probe the nature of dark energy – the as yet unexplained driver behind the accelerating expansion of the universe; study the architecture of other solar systems; and advance understanding of how galaxies, stars, and black holes evolve. This science program, together with the mission’s moderate cost, low technical risk, and mature design were key factors in its top ranking among large space missions.

NASA initially considered a design of WFIRST with a 1.3-meter aperture. In 2012, the National Reconnaissance Office gave NASA hardware for two 2.4-meter telescopes -- the same size as the currently operating Hubble Space Telescope. NASA dubbed these the Astrophysics Focused Telescope Assets (AFTA) and began to study an alternative to the original telescope design. After the NRO telescopes were acquired, NASA also began to consider the addition of a coronagraph, an instrument that would advance goals in the study of exoplanets.

The new Research Council report compares the WFIRST/AFTA design both with and without a coronagraph to the original mission concept, on the basis of their science objectives, technical complexity, and programmatic rationale, including projected cost. The report does not recommend which design NASA should adopt.

The committee that wrote the report found that the larger aperture provided by the 2.4-meter design “will significantly enhance the scientific power of the mission” for cosmology, exoplanet surveys, and general infrared survey science, such that the mission is consistent with the scientific goals described in the decadal survey. This new design also makes inclusion of a coronagraph attractive.

However, the inherited hardware was designed for another purpose, and the degree to which changes to the hardware must be made to accommodate a different launch vehicle and scientific requirements is uncertain at this time. This uncertainty contributes to higher technical risk and a greater likelihood that costs will increase beyond current estimates, the report says. The WFIRST/AFTA without the coronagraph was estimated to cost $2.1 billion, up from an estimate of $1.8 billion for an earlier design which was more similar to the mission recommended in the 2010 survey report.

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ESA Selects PLATO Exoplanet Telescope

A telescope to find rocky worlds around other stars has been selected for launch by the European Space Agency's (ESA) Science Policy Committee.

Known as Plato, the mission should launch on a Soyuz rocket in 2024.

The observatory concept was chosen following several years of assessment in competition with other ideas.

It is expected to cost ESA just over 600 million euros, although hardware contributions from member states will take this closer to a billion (£800m [$822 Million -me]).

Astronomers have so far found over 1,000 planets beyond our Solar System, but none as yet has been shown to be truly Earth-like in terms of its size and distance from a Sun similar to our own.

The PLAnetary Transits and Oscillations of stars mission will look to change that.

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Gaia Mission Could be Used to Help Map Exoplanets

Gaia, a mission from the European Space Agency (ESA), aims to chart a 3-D map of the Milky Way by surveying more than 1 billion stars, amounting to about 1 percent of the stars in the galaxy. Its goal is to make the largest, most precise map of where Earth dwells by observing the position of each of these stars 70 times over five years.

To pinpoint the position of a star in 3-D — a field known as astrometry — Gaia will measure the distance of the star from the Sun. The satellite will do so by watching how its position shifts over time. As the Earth orbits the Sun, the apparent positions of stars change with regard to each other due to how our viewpoint has moved, a phenomenon known as parallax.

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Europa has Eruptive Water Jets Like Enceladus

NASA’s Hubble Space Telescope has observed water vapor above the frigid south polar region of Jupiter's moon Europa, providing the first strong evidence of water plumes erupting off the moon's surface.

Previous scientific findings from other sources already point to the existence of an ocean located under Europa's icy crust. Researchers are not yet fully certain whether the detected water vapor is generated by erupting water plumes on the surface, but they are confident this is the most likely explanation.

Should further observations support the finding, this would make Europa the second moon in the solar system known to have water vapor plumes. The findings are being published in the Dec. 12 online issue of Science Express, and reported at the meeting of the American Geophysical Union in San Francisco.

“By far the simplest explanation for this water vapor is that it erupted from plumes on the surface of Europa,” said lead author Lorenz Roth of Southwest Research Institute in San Antonio. "If those plumes are connected with the subsurface water ocean we are confident exists under Europa's crust, then this means that future investigations can directly investigate the chemical makeup of Europa's potentially habitable environment without drilling through layers of ice. And that is tremendously exciting."

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Water Signature Seen For Three Exoplanets

EXOPLANET TRANSIT SPECTROSCOPY USING WFC3: WASP-12 b, WASP-17 b, AND WASP-19 b

Authors:

Mandell et al

Abstract:

We report an analysis of transit spectroscopy of the extrasolar planets WASP-12 b, WASP-17 b, and WASP-19 b using the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We analyze the data for a single transit for each planet using a strategy similar, in certain aspects, to the techniques used by Berta et al., but we extend their methodology to allow us to correct for channel- or wavelength-dependent instrumental effects by utilizing the band-integrated time series and measurements of the drift of the spectrum on the detector over time. We achieve almost photon-limited results for individual spectral bins, but the uncertainties in the transit depth for the band-integrated data are exacerbated by the uneven sampling of the light curve imposed by the orbital phasing of HST's observations. Our final transit spectra for all three objects are consistent with the presence of a broad absorption feature at 1.4 μm most likely due to water. However, the amplitude of the absorption is less than that expected based on previous observations with Spitzer, possibly due to hazes absorbing in the NIR or non-solar compositions. The degeneracy of models with different compositions and temperature structures combined with the low amplitude of any features in the data preclude our ability to place unambiguous constraints on the atmospheric composition without additional observations with WFC3 to improve the signal-to-noise ratio and/or a comprehensive multi-wavelength analysis.

After Kepler, TESS is Next

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