K. Uckert

Multifrequency monitoring of the blazar 0716+714 during the GASP-WEBT-AGILE campaign of 2007

Aims. Since the CGRO operation in 1991–2000, one of the primary unresolved questions about the blazar γ -ray emission has been its possible correlation with the low-energy (in particular optical) emission. To help answer this problem, the Whole Earth Blazar Telescope (WEBT) consortium has organized the GLAST-AGILE Support Program (GASP) to provide the optical-to-radio monitoring data to be compared with the γ -ray detections by the AGILE and GLAST satellites. This new WEBT project started in early September 2007, just before a strong γ -ray detection of 0716+714 by AGILE. Methods. We present the GASP-WEBT optical and radio light curves of this blazar obtained in July–November 2007, about various AGILE pointings at the source. We construct NIR-to-UV spectral energy distributions (SEDs), by assembling GASP-WEBT data together with UV data from the Swift ToO observations of late October. Results. We observe a contemporaneous optical-radio outburst, which is a rare and interesting phenomenon in blazars. The shape of the SEDs during the outburst appears peculiarly wavy because of an optical excess and a UV drop-and-rise. The optical light curve is well sampled during the AGILE pointings, showing prominent and sharp flares. A future cross-correlation analysis of the optical and AGILE data will shed light on the expected relationship between these flares and the γ -ray events.

The high activity of 3C 454.3 in autumn 2007. Monitoring by the WEBT during the AGILE detection

The quasar-type blazar 3C 454.3 underwent a phase of high activity in summer and autumn 2007, which was intensively monitored in the radio-to-optical bands by the Whole Earth Blazar Telescope (WEBT). The gamma-ray satellite AGILE detected this source first in late July, and then in November-December 2007. In this letter we present the multifrequency data collected by the WEBT and collaborators during the second AGILE observing period, complemented by a few contemporaneous data from UVOT onboard the Swift satellite. The aim is to trace in detail the behaviour of the synchrotron emission from the blazar jet, and to investigate the contribution from the thermal emission component. Optical data from about twenty telescopes have been homogeneously calibrated and carefully assembled to construct an R-band light curve containing about 1340 data points in 42 days. This extremely well-sampled optical light curve allows us to follow the dramatic flux variability of the source in detail. In addition, we show radio-to-UV spectral energy distributions (SEDs) at different epochs, which represent different brightness levels. In the considered period, the source varied by 2.6 mag in a couple of weeks in the R band. Many episodes of fast (i.e. intranight) variability were observed, most notably on December 12, when a flux increase of about 1.1 mag in 1.5 hours was detected, followed by a steep decrease of about 1.2 mag in 1 hour. The contribution by the thermal component is difficult to assess, due to the uncertainties in the Galactic, and possibly also intrinsic, extinction in the UV band. However, polynomial fitting of radio-to-UV SEDs reveals an increasing spectral bending going towards fainter states, suggesting a UV excess likely due to the thermal emission from the accretion disc.

WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008 Unveiling different emission components

In 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the XMM-Newton satellite, to study its emission properties. The source was monitored in the optical-to-radio bands by 37 telescopes. The brightness level was relatively low. Some episodes of very fast variability were detected in the optical bands. The X-ray spectra are well fitted by a power law with photon index of about 2 and photoelectric absorption exceeding the Galactic value. However, when taking into account the presence of a molecular cloud on the line of sight, the data are best fitted by a double power law, implying a concave X-ray spectrum. The spectral energy distributions (SEDs) built with simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations suggest that the peak of the synchrotron emission lies in the near-IR band, and show a prominent UV excess, besides a slight soft-X-ray excess. A comparison with the SEDs corresponding to previous observations with X-ray satellites shows that the X-ray spectrum is extremely variable. We ascribe the UV excess to thermal emission from the accretion disc, and the other broad-band spectral features to the presence of two synchrotron components, with their related SSC emission. We fit the thermal emission with a black body law and the non-thermal components by means of a helical jet model. The fit indicates a disc temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.

Rapid assessment of high value samples: An AOTF-LDTOF spectrometer suite for planetary surfaces

We discuss the development of a miniature near-infrared point spectrometer, operating between 1.7-3.45 μm, based on acousto-optic tunable filter (AOTF) technology. This instrument may be used to screen and corroborate analyses of samples containing organic biomarkers or mineralogical signatures suggestive of extant or extinct organic material collected in situ from planetary surfaces. The AOTF point spectrometer will be paired with a laser desorption time-of-flight (LDTOF) mass spectrometer and will prescreen samples for evidence of volatile or refractory organics before the laser desorption step and subsequent mass spectrometer measurement. We describe the AOTF point spectrometer instrument and present laboratory analysis of geological samples of known astrobiological importance. We also present LDTOF spectra of the same samples analyzed with the AOTF, which highlights the value of a comparative data set with the two instruments. We discuss plans for the integration of the two instruments, which is scheduled to take place in the first half of 2012. The AOTF-LDTOF instrument pairing offers the powerful advantage of cross-checked chemical analyses of individual samples, which can reduce chemical and biological interpretation ambiguities.

Results from an integrated AOTF-LDTOF spectrometer suite for planetary surfaces

On future landed missions to Mars and small solar system bodies, efficient sample prescreening will be necessary to select interesting targets for further analysis by analytical instruments with very limited time and power resources. Near infrared spectroscopy is well suited for rapid and non-invasive identification of mineral classes, and for determining the possible presence of organic molecules. Here we describe a miniature acousto-optic tunable filter (AOTF) point spectrometer that is tunable from ~1.6 - 3.6 μm. It identifies minerals associated with aqueous environments at sample scales of ~1 mm, as well as organic molecules and volatiles. The AOTF point spectrometer was integrated with a laser desorption time-of-flight (LDTOF) mass spectrometer developed at NASAs Goddard Space Flight Center, and can be used to prescreen samples for evidence of organics before the laser desorption step and subsequent mass spectrometer measurement. The LDTOF mass spectrometer provides pulsed-laser desorption and analysis of refractory organic compounds up to 150,000 Da on a spatial scale of 50-100 μm, determined by the laser spot size at the target. The recent integration of the two instruments allowed for coincident spectral measurements of geologic samples; follow-up measurements from the LDTOF were taken from an identical region on the samples of interest, allowing for a direct comparison between the two complementary data sets. We present measurements of a standard sample suite consisting of sulfates, carbonates, clay minerals, and iron oxides. We also compare AOTF and LDTOF spectra of calcite, as well as gypsum doped with phthalic acid and valine, and discuss the relationship between reflectance spectra acquired by the AOTF and the LDTOF mass spectra. Finally, we discuss measurements made of irradiated ices such as those found in areas of high astrobiological interest like Europa.

Analysis of aqueous environments by laser desorption/ionization time-of-flight mass spectrometry

Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) has been developed and used to characterize different groups of hydrous minerals. We have advanced the technique by including reversed polarity, precision ion gating, and a curved field reflectron mass analyzer. Reversed polarity provides capabilities in achieving complementary compositional information of the materials, and ion gating enhances the selectivity and sensitivity in specific mass ranges. Representative reference minerals including sulfates, clays, serpentine, and naturally collected complex samples have been analyzed by LD-TOF-MS as well as infrared (IR) spectroscopy, to provide supporting information. We demonstrate that mass spectrometry can identify water in mineral species, and reveal the presence of aqueous environments. Miniaturized LD-TOF-MS is a valuable instrument technique for the in situ characterization and analysis of samples as part of future landed planetary missions and astrobiology explorations.

A comparative study of in situ biosignature detection spectroscopy techniques on planetary surfaces

We demonstrate the biosignature detection capabilities of several classes of instruments, including a compact laser desorption/ionization time-of-flight mass spectrometer, an acousto-optic tunable filter IR point spectrometer, a laser-induced breakdown spectrometer, and a scanning electron microscope. We collected biotic and abiotic calcite, gypsum, and manganese oxide samples from Fort Stanton Cave to identify the presence of biomarkers with each instrument class. We find evidence of biologic activity in these samples including the presence of organic molecules, macroscopic and microscopic morphological features consistent with fossilized mircobes, and the presence of trace elements consistent with the biotic precipitation of minerals. The identification of extant or extinct microbial life is best supported by a suite of biosignatures, rather than a single observation. We demonstrate the unique biosignature detection results of each instrument class and discuss the importance of developing an instrument suite for future landed astrobiology missions on other planetary surfaces.

Demonstration of a portable AOTF IR spectrometer for in situ exploration of planetary surfaces

We discuss the development of a portable NIR reflectance point spectrometer based on acousto-optic tunable filter (AOTF) technology for future in situ geologic investigations of planetary surfaces. AOTFs are low power devices that operate on the principle of diffraction in a birefringent crystal. We have demonstrated the efficacy of this technique in extreme subterranean environments using the Portable AOTF Spectrometer for Astrobiology (PASA) to detect spectral biosignatures consistent with microbial alteration of geologic samples. PASA measures the IR reflectance spectrum of geologic samples in the 1.6 - 3.6 μm range with a resolution of λ/Δλ ≈ 250 - 400. We present the development and specifications of PASA, results from these expeditions, and discuss potential applications of a portable NIR point spectrometer based on AOTF technology for future landed or roving missions to other Solar System bodies.

Design of a low cost mission to the Neptunian system

Visited only by Voyager 2 in 1989, Neptune and its moon Triton hold important clues to the formation and evolution of the solar system and exoplanetary systems. Neptune-sized planets are the most commonly discovered exoplanets to date. Neptune, an ice giant, is theorized to have migrated from its formation location in the early solar system. This migration affects the expected interior structure, composition, and dynamical evolution of the planet. Triton is conjectured to be a heavily-processed, captured Kuiper Belt Object (KBO), a remnant from the early solar nebula and unique in our solar system. Triton may possess a subsurface aqueous ocean, making it an important astrobiological target. The 2013-2022 Planetary Science Decadal Survey [1] identified a number of high priority science goals for the Neptunian system, including understanding the structure, composition, and dynamics of Neptunes atmosphere and magnetosphere, as well as surveying the surface of Triton. Following these guidelines, we present a low cost flyby mission concept to Neptune and Triton: TRIDENT (Taking Remote and In-situ Data to Explore Neptune and Triton). TRIDENT would carry six instruments and a government furnished atmospheric probe and would provide significant improvements over the scientific measurements undertaken by Voyager 2. In this paper, we first provide a detailed overview of the science questions pertaining to Neptune and Triton and of the science investigations necessary to elucidate them. We then present the design of TRIDENTs instrument suite, the trajectory and the spacecraft, as well as the motivation behind each of our choices. In particular, we demonstrate that, for a mission launched on an Atlas V 551, a Neptune orbiter mission would be infeasible with current technology levels without the use of aerocapture. We therefore present a flyby mission concept with a cost lower than FY2015

Spectral mixture and chemometric algorithms applied to the identification of biosignatures on planetary surfaces

1.5B. We also show that the proposed mission has low risk and significant margin and that several de-scope options are available in the event of cost overruns. This study was prepared in conjunction with the NASA 2013 Planetary Science Summer School. The work presented is a hypothetical mission proposal, for planning and discussion purposes only. It does not represent NASAs interests in any way.