Biosignatures Part IV: The James Webb Telescope

Up until now, I have spoken of current findings. However I will speak of a mission that is set to launch in the coming years. The James Webb is set to launch in 2018. The mission will consist of four science packages–(see links at end of post for the three other aspects of the telescope) and I will speak of: Webb Science: Planets & Origins of Life. However, more background may be in order.


Fig. 1 Mission Patch for STS 82—Shuttle Discovery

One major contributor to the understanding of life’s origins has been the Hubble Space Telescope. During the second servicing mission for Hubble ( 1997), STS 82 (Shuttle Discovery) installed the NICOS instrument package onto Hubble.

Fig. 2 Methane Absorption by the Atmosphere of Extrasolar Planet 189733b, detected by the Hubble Space Telescope using the NICOS suite of instruments.

Credit: NASA, ESA, and A. Feild (STScI)

The extra-solar planetary system may be sought with binoculars in the Northern Hemisphere—it is: “The star can be found with binoculars 0.3 degrees east of the Dumbbell Nebula (M27).” —-According to Wikipedia. See below for an excellent image.

Fig. 3

Credit: NASA, ESA, A. Fujii, and Z. Levay (STScI)


When we speak of chemical or biosignatures from exo-solar planets—the upcoming launch of the James Webb Space Telescope will be capable of discerning biosignatures which have eluded astronomers for some time.

Fig. 4 Schematic of James Webb Telescope

From web site:

“The Observatory is the space-based portion of the James Webb Space Telescope system and is comprised of three elements, the Integrated Science Instrument Module (ISIM), the Optical Telescope Element (OTE), which includes the mirrors and backplane, and the Spacecraft Element, which includes the spacecraft bus and the sunshield”

Researchers have explored the manner in which the telescope might be used for the exploration and elucidation of biosignatures and atmospheric chemistry in the near future. The understanding of biosignatures of earth-like exo-planets entails the detection of exo-atmospheres that are in a dis-equilibrium state. At the minimum it may take several earth years to monitor and unambiguously detect exo-planet planet atmospheres which would contain methane, carbon dioxide, oxygen, ozone, and water. The atmospheric concentrations would be in a state of flux if there is a sun-like star; the atmospheric chemistry would be somewhat familiar as on the earth. Let me illustrate by reaction type:

O3 + hv
à O2 + O


H2O + O à 2OH

CH4 + OH à CH3 + H2O

The reactions in equation 1 illustrate how ozone dissociates to oxygen and an oxygen radical to ultimately form water and a methyl radical.

O2 + hv à O + O

2)           O + O2 + M à O3 + M

O3 + hv à O2 + O

O3 + O à2O2

The third reaction delineates the how nitrous oxide reacts with an oxygen radical to form two separate molecules of nitric oxide.

3             N2O + O à 2NO

The final reaction set is a proposed for marine environs—where methyl chloride (from a marine source) may react twice to ultimately form hydrochloric acid and a chlorine radical.

CH3Cl + OH à Cl + H2O

4)           CH3Cl + hv àCH3 + Cl

CH3Cl + Cl à HCl + CH2Cl2

Although the reaction sequences are rather cryptic (in nature), they are meant to illustrate the type of chemistry which readily takes place within our own atmosphere—as well as possible extra-solar candidates. Hopefully, one may infer that an earth-like candidate may have similar atmospheric chemistry. Thus, it may be simpler to find a dis-equilibrium state which may closely match our own (known) chemistry.

Of major importance in our understanding in how life started on our planet is the ability to understand chemical and (possible) biosignatures emanating from distant earth-like planets. Although some chemical signatures have been measured—we have not seen a biosignature beyond the Earth. Not only will we be assured that life maybe propitious throughout but intelligent life may not be that far away as well.



HD189733b URL

Journal paper on finding (original found at e-print archive) from Hubble site (paste link into your browser):
  1. Webb Science: The End of the Dark Ages: First Light and Reionization URL
  • Webb Science: The Assembly of Galaxies URL
  • Web Science: The Birth of Stars and Protoplanetary Systems URL

Atmospheric chemistry models based upon the following reference (and references cited therein):

Sarah Rugheimer , et al. Spectral Fingerprints of Earth-like Planets around FGK Stars, (To appear in the journal Astrobiology)—may be found at Physics e-print server


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