Terrestrial Planet Finder (tpf)

AST 309 part 2: Extraterrestrial Life

Terrestrial Planet Finder (TPF)

• Terrestrial Planet Finder (TPF)

• Mission goals:

• Target:

• Nearby stars (why?)

• Sun-like stars (why)?

• Detect:

• 1. Habitable Planets

• 2. Life using Biosignatures

Kepler looks at stars

• Kepler looks at stars

• >1000 light years away

• (too see as many as possible)

• These are too far away for TPF!

There are ~100 stars within 22 light years

• There are ~100 stars within 22 light years

• Step 1: find the Earth-like planets:

• Radial velocity?

• Astrometry?

• Direct Imaging?

Introducing the Neighbors:

• α Cen A [G2 V] V=0.01

• Teff = 5790 K

• M = 1.10 M

• α Cen B [K1 V] V=1.33

• Teff = 5260 K

• M = 0.93 M

• Binary:

• P = 79.91 yrs

• a = 23 AU

• e = 0.52

• i = 79°

Direct Imaging:

• Need to go to space too!

• Contrasts of 10-9 or better at very small angles!

• 3 different concepts:

• Advanced coronagraph (TPF-C)
• Nulling Interferometer (TPF-I)
• External Occulter

TPF-C:

TPF-C:

TPF-I:

Biosignatures:

• The most convincing spectroscopic evidence for life as we know it is the simultaneous detection of large amounts of oxygen as well as a reduced gas, such as methane or nitrous oxide, which can be produced by living organisms. Oxygen, methane, and nitrous oxide are produced in large amounts by plants, animals, and bacteria on Earth today, and they are orders of magnitude out of thermodynamic equilibrium with each other.

Biosignatures:

Biosignatures:

Biosignatures:

Biosignatures:

• We must be able to identify potential "false-positives," the nonbiological generation of planetary characteristics that mimic biosignatures. For example, while atmospheric methane may be a possible biomarker on a planet like Earth, especially when seen in the presence of oxygen, on a body like Titan it is simply a component of the atmosphere that is non-biologically-generated.

• Theoretical and experimental research and analysis are necessary to secure a detailed understanding of the biosignatures that might be found.

Biosignatures:

Biosignatures: