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The search for life in Solar System bodies such as Mars and Ocean Worlds (e.g., Europa and Enceladus) is an ongoing and high-priority endeavor in space science, even ∼ five decades after the first life detection mission at Mars performed by the twin Viking landers. However, the in situ detection of biosignatures remains highly challenging, both scientifically and technically. New instruments are being developed for detecting extinct or extant life on Mars and Ocean Worlds due to new technology and fabrication techniques. These instruments are becoming increasingly capable of both detecting and identifying in situ organic biosignatures that are indicative of life and will play a pivotal role in the search for evidence of life through robotic lander missions. This review article gives an overview of techniques used for space missions (gas chromatography, mass spectrometry, and spectroscopy), the further ongoing developments of these techniques, and ion mobility spectrometry. In addition, current developments of techniques used in the next-generation instruments for organic biosignature detection are reviewed; these include capillary electrophoresis, liquid chromatography, biosensors (primarily immunoassays), and nanopore sensing; whereas microscopy, biological assays, and isotope analysis are beyond the scope of this paper and are not covered.

Rotational and vibrational dependence of photodissociation cross sections and oscillator strengths to the continuum levels of the H_2{ \,}\bpxo{} and \dxo{} states have been examined. The electron-impact excitation, dissociation and emission cross sections of the \bpxi{} and \dxi{} band systems have been obtained for the first time over a wide energy range by using calculated continuum oscillator strengths along with previously published discrete transition probabilities and Lyman and Werner bands excitation functions. The present \bpxo{} photodissociation cross section from the Ji = 0 level is in excellent agreement with that obtained by Glass-Maujean (1986 Phys. Rev. A 33 346-50). Photoexcitation from the \xxo{(v_i=0)} state to the \dxo{} continuum is found to be weak. The present calculation shows significant contribution of quasi-resonance, which arises from transitions to the quasi-bound levels above the dissociation limit but stabilized by the centrifugal potential. The quasi-resonance is largely responsible for the significant rotational dependence of the continuum oscillator strength of the \bpxo{}-\xxo{(0)} transition, which, in turn, leads to the noticeable temperature dependence of electron-impact excitation and emission cross sections. \bpxi{} and \dxi{} electron-impact excitation, emission, and dissociation cross sections, important for modelling dayglow and auroral activity in the atmospheres of the outer planets, are presented. [ABSTRACT FROM AUTHOR]