Probing Life with Planet Searching and Habitat Evaluation: Evidence

from Moon, Mars and WASP-96b

Angelina Hubertus

Greenwich Academy, Oenoke Ridge, New Canaan, U.S.A.

Keywords: Planet Searching, Habitat Evaluation, Transmission Spectrum Evaluation, WASP-96b.

Abstract: Contemporarily, evaluation for the habitability of planet remain an extreme challenging task though plenty of

advanced techniques have been proposed and implemented in astrophysics observation. So far, more than 4

thousand extra-planets have been observed while only about less than 10 planets show similar habitat like

earth in terms of the state-of-art measurement tools, indicating the possibility for existence of life. With this

in mind, this study will systematically discuss and analyse the probing life process with the demonstration of

planet searching (the five common methods) and habitat evaluation based on sampling as well as spectrum

analysis. To be specific, three most investigated celestials are selected as typical examples to discuss the

probing life results, i.e., Moon, Mars and WASP-96b. According to the analysis, the current collected results

will be evaluated and the limitations for the current methods will be discussed. These results will offer a

guideline for further exploration regarding to life probing in universe.

1 INTRODUCTION

The probing life in planets remains a tough issue even

under the rapid developments of astrophysics

observation techniques (Cockell, 2020). Among

various challenges, two tasks are identified as the first

rank issues that need to be addressed, i.e.,

nonluminous celestial searching and habitat

evaluation for the celestials. As for nonluminous

celestial searching, different from stars that emits

light, they can only be detected based on indirect

measures or relevant direct events. Typically, there

are more than 5 methods to achieve the goal including

transit, radial velocity based on Doppler effects,

gravitational lensing, etc. (Rice, 2014). With regard

to habitat evaluations, it can only be inferred from the

orbits information or emission spectrum for most of

planets, which offers the elements distributions and

possible atmosphere (Kaltenegger, 2017; Seager,

2014). For some nearby celestials, it is available to

collects some soils or shadow images to retrieve more

details information, e.g., the Moon (Glavin et al.,

2010) and Mars (Joseph et al., 2019).

In recent years, exoplanets have been the fastest

growing discipline in astronomy. More than 700

confirmed and more than 3,000 unconfirmed planets

have been found using five further developed

precision observation methods. Their universality and

diversity not only challenge the classical planetary

origin models, but also provide clues for new

conceptual theories. In addition, one can look at the

atmospheres, the densities, the elliptical shapes of

some of the planets. The key conclusions include that

planets begin with nuclear accretion, that many

planets undergo large scale migrations, that habitable

planets are common, that water-filled planets exist,

and that planetary systems generally evolve

dynamically. In the near future, observations and

theoretical developments in this area will continue to

advance rapidly, uncovering the secrets of the origin

of life.

In the 21st century, the astronomical community

has taken exoplanet detection, habitable planets and

life signal search as a major strategic goal (The

Project Team of Research on Development Strategies

2021-2035, 2023; National Academies of Sciences,

Engineering, and Medicine, 2021).

The discipline of exoplanets is a new subject

which has developed rapidly in the several decades.

The study of exoplanets is important for answering

questions such as whether there is other life in the

universe and the place and significance of human

beings in the universe (Zhou et al. 2024).

Under the circumstances of the novel discoveries

for new planet or updated information of the celestials

136

Hubertus, A.

Probing Life with Planet Searching and Habitat Evaluation: Evidence from Moon, Mars and WASP-96b.

DOI: 10.5220/0013001700004601

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 1st International Conference on Innovations in Applied Mathematics, Physics and Astronomy (IAMPA 2024), pages 136-144

ISBN: 978-989-758-722-1

based on various state-of-art facilities, it is necessary

to present a comprehensive analysis for the searching

methodology and judgement criteria for evidence of

habitability. On this basis, the planet searching

methodology as well as habitat evaluation

methodology will be discussed and introduced.

Subsequently, probing life for three specific celestials

will be discussed (i.e., Moon, Mars and WASP-96b),

which are also the most investigated one nowadays.

Based on the analysis, the current limitations and

further developed techniques will be discussed.

2 PLANET SEARCH

METHODOLOGY

The main methods of exoplanet detection at present

including apparent velocity, transit, microlensing,

direct imaging, astrometry, etc. With the rapid

developments of data retrieving and system analysis

techniques. Machine learning techniques are also

applied to cross validation the search results and help

to filer data, The crystallization of science and

technology development. Exoplanet detection

involves optics/red. Outer astronomy, space science

and space technology, the development of this

discipline will be straight. Connected to push space

ultra high precision photometry technology, high

sensitivity of weak spectral signal, detection

technology, high-performance imaging detection

technology, ultra-high contrast imaging technology,

ultra-high precision astrometry technology, space

light interferometry technology, satellite, attitude

control technology and satellite formation flight

technology have made new progress breakthrough

(Santos, 2008; Zhou et al. 2024). Detecting Earth 2.0,

discovering a second solar system, extraterrestrial life

Figure 1: Footprint, progress and cross validation of different planet searching schemes (results are combination of Zhou et

al. 2024; Kaltenegger 2017; Howard 2013 and Tsapras 2018).

Probing Life with Planet Searching and Habitat Evaluation: Evidence from Moon, Mars and WASP-96b

137

and more Exocivilizations are all breakthroughs from

zero to one in the progress of human civilization as

well as making major breakthroughs in astronomy, it

also promoted geology and planetary science,

astrochemistry, astrobiology, and atmospheric

science. The intersection of these disciplines to

astronomy and related sciences as well as the

development and breakthrough in the field of science

and technology has acted as a catalyst.

To be specific, there are at least 7 methods to

realize planet searching and the relevant milestones

as well as principles for the methodology are

presented in Fig. 1. Astrometry, the earliest method

used to search for exoplanets, focuses on precisely

measuring the motion of a star to determine where

planets are being dragged by its gravity. The

advantage of astrometry is that it can calculate

planetary masses with relatively high accuracy, and it

is particularly sensitive to planets with large orbits.

However, this method requires very high accuracy,

requiring years or even decades of observation to

confirm the results. HD176051b, discovered in

October 2010, is the only confirmed astrometric

exoplanet to date (Ginski et al., 2012). Hopes are

pinned on the European Space Agency's Gaia space

astrometry project, which launched in December

2013. Not long ago, the project released its second

batch of scientific data. Gaia has determined the

brightness, spectral signature, three-dimensional

position and motion of more than a billion stars and

created the most accurate three-dimensional map of

the Milky Way to date. Researchers estimate that the

new astrometry is expected to help them find tens of

thousands of new exoplanets.

Direct imaging is another common method, which

works like taking spectra of exoplanets based on the

facilities directly and analysis the typical peak.

Nevertheless, it requires the planet satisfying certain

size that it is not so close to its parent star that it is

obscured by its light, and requires a high observer.

Not only are they equipped with advanced

photography equipment, but they also have powerful

coronagrameters, which can effectively block out the

dazzling light of their parent stars and ensure clear

images. Due to the difficulty of direct imaging, only

40 exoplanets have been found by this method so far.

Unlike direct imaging methods, most exoplanets

are found through indirect methods. The radial

velocity method is a widely adopted indirect method

in terms of Doppler effect, which was used for the

first extrasolar planet, 51b Pegasi (Wang and Peng,

2015). The planets also exert a pull on the star as they

orbit it, and the spectrum of light emitted by the star

is shifted red and blue accordingly, from which the

radial velocity of the star can be obtained. Thousands

of exoplanets have been discovered based on

advanced astronomical equipment such as the

HARPS and the HIRES. There is a well-known

empirical formula for RV method (Lovis and Fischer,

2010):

𝑅𝑉 =

28.4𝑚𝑠



√

1 −𝑒



𝑚



𝑠𝑖𝑛𝑖

𝑀





𝑚



𝑀













𝑃

1𝑦𝑟









)

Here, RV is the measure value, e corresponds to the

value of eccentricity, P is the cycling period, i is the

inclination angle, m

, M

and m

corresponds to

the mass of system, solar, Jupiter and measure

celestial, respectively.

Another method is transit, in which an exoplanet

passes between its parent star and Earth, blocking

some of the light from the star, causing a slight

decrease in the brightness of the star one observes.

The detection of such slight variations in light can be

used to predict the presence of exoplanets. On

account of the rare feature for transits, as many stars

as possible must be monitored in order to find as

many exoplanets as possible. Kepler space telescope

since the launch in March 2009, the search for

exoplanets harvest, so far human found nearly 3800

exoplanets, 70% is found by it, it is called "planet

hunter" reputation (Howard, 2013). Although Tess

also uses the transit method to search for exoplanets,

its search strategy is different from its predecessors.

Unlike Kepler, which monitors a small patch of the

sky for years on end, Tess will be in "survey" mode,

surveying almost 90 percent of the entire sky for two

years, focusing on the solar system neighbours.

In addition to the above methods, there are some

other approaches including gravitational

microlensing (Tsapras, 2018), pulsar counter, special

relativity method (Wolszczan, 2012). For the

gravitational microlensing method, when a star

moves in front of a background star observed from

the Earth, the light emitted by the star will be

refracted and amplified by the gravitational action as

if it were passing through the lens, and a light curve

will be generated. If the star had planets, it would

have a second-order light curve. Thus, once a second-

order light curve is found, the existence of a planet

can be proved. This approach is most likely to be

fruitful when looking at stars between the Earth and

the galactic centre, which can provide many

background stars. For the pulsar timing method, it is

particularly suitable for finding planets moving

around pulsars. Pulsars are extremely dense remnants

of supernova explosions that emit intense pulses of

radiation as they spin at high speeds. The first

IAMPA 2024 - International Conference on Innovations in Applied Mathematics, Physics and Astronomy

138

confirmed planets were found using this method (the

two planets of pulsar PSR1257+12). The special

relativity method is a new method that uses Einstein's

special theory of relativity to guide the discovery of

exoplanets. Changes in the star's brightness as a result

of the planet's motion, I,e,m the latter's gravitational

pull triggers relativistic effects that cause the photons

that make up light to "pile up" which helps the

discovery of the Kepler-76b.

3 PLANET HABITAT

EVALUATION

METHODOLOGY

At present, the detection and research of exoplanets

are very active, forming a development trend of

finding exoplanets, accurate characterization of

planetary systems (mass, orbital parameters,

atmospheric composition, etc.), discovery of

habitable planets and characterization of habitable

planets. A large quantity of space and ground

telescope projects have been planned and carried out

around this idea of exoplanet discipline development,

and some important progress has been made in

observation and theory (Madhusudhan, et al., 2020).

The habitability of a planet can be measured in a

number of ways, but typical indicators are as follows.

ESI stands for Earth Similarity index and is an index

that measures how similar other planets are to the

Earth, ranging from 0 to 1, with the Earth's own

similarity index represented by 1. The Earth

Similarity Index is designed for planets, but can also

be used for large natural satellites and other celestial

bodies (Schulze-Makuch, et al., 2011). The Earth

similarity index can be calculated by plugging in the

planetary radius, density, detachment velocity and

surface temperature. Some typical results for ESI

metric are presented in Fig. 2. SPH is an index of

suitability for vegetation growth, ranges from 0 to 1

and depends on surface temperature and relative

humidity. HZD indicates how far a planet is from the

centre of the star's Habitable zone. Values range from

-1 to 1. A value of -1 indicates the innermost part of

the habitable zone, while a value of 1 indicates the

outermost part of the habitable zone. It depends on the

brightness and temperature of the star, and of course

on the radius of the planet's orbit. HZC denotes the

amount of planetary composition. A value close to 0

means the planet is likely to be iron-stone-water, a

value below -1 means it's likely to be mostly iron, and

a value above 1 means it's likely to be gas. HZC

depends on the mass and radius of the planet. HZA is

used to measure and assess the potential of a planet to

have a Habitable Atmosphere. A value below -1

indicates a thin or almost no atmosphere, a value

above 1 indicates a very likely thick hydrogen

atmosphere (like a gas giant planet), and a value

between -1 and 1 indicates an atmosphere potentially

suitable for life. Whereas, it's important to note that 0

doesn't mean the ideal atmosphere for life. HZA

depends on the mass of the planet, the radius, the orbit

size and the brightness of the star (Méndez, et al.,

2021).

The most common and power tools to analyse the

habitat with maximum likelihood is spectrum

estimations. However, the intensity is much smaller

for planet compared to stars. Hence, the transit

schemes should be considered to collect the spectrum

signals of the planet. In fact, researchers need to find

some kind of quick assessment score that they can use

as a metric to list promising planets, to determine

which of the billions of celestial bodies out there are

more suitable. The habitability of exoplanets is a

challenging problem. At present, researchers have

proposed new classification schemes (machine

learning) for the existing habitability indicators and

exoplanets. Currently, astronomers can use

computational intelligence techniques to assess

habitability scores and automate the exoplanet

classification process. They investigated how solving

convex optimization techniques can cross-validate

ML-based exoplanet classification. Examples include

computing new metrics, e.g., the CDHS and CEESA.

Despite recent criticism of exoplanet habitability

rankings, human beings are convinced that the field

must continue to evolve to use all available

astroinformatics, artificial intelligence (AI), and

machine learning mechanisms (Safonova et al., 2021).

Indeed, the most direct method to estimate the

planet habitat is sending detectors as close as possible

to the orbits or even collecting the sample (gas, soil,

elements, etc.) directly. Nevertheless, in

consideration of the distances, the scenarios are tough

to fulfil. In the subsequent sections, three cases will

be discussed, where two of them (i.e., Moon and

Mars) are feasible to achieve the goal to direct

analysis.

4 SPECIFIC CASES ANALYSIS

4.1 Moon

As a matter of fact, Moon is a satellite instead of

planet, whereas it is the closest celestial for human

beings. On this basis, the searching life schemes of

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139

Figure 2: Typical examples of ESI metric and habitability (Data collected from: (Madhusudhan, et al., 2020; Safonova et al.,

2021 and Schulze-Makuch, et al., 2011).

Moon could offer insights for probing life for others.

If one wants to explore the solar system, it has to open

the door of the moon. For the moon, which is as large

as a whole continent, man has left only a few steps on

it. As Earth's closest planetary neighbour, the moon

holds great potential as a new source of scientific

progress and economic growth. In fact, NASA's

Lunar Orbital Reconnaissance Vehicles have been

imaging and mapping the moon for more than a

decade to conduct scientific research and prepare for

humans to land on the moon again. In the future,

NASA will deliver its next lunar Exploration robot,

the VIPER, which will conduct a scientific

investigation of lunar volatiles at the South Pole of

the moon. The data generated by VIPER will inform

future lunar in situ resource utilization (ISRU)

technologies.

In recent years, with China's lunar exploration

program, some lunar soil has been brought back (

Li,

et al., 2022

), but the conclusions obtained are the same

as satellite observations, and there is no evidence of

life on the moon. The reasons are as follows. First, the

moon has no atmosphere. Its surface atmospheric

pressure is only one billionth of Earth's, and it is

almost a vacuum. Due to the lack of atmospheric

protection, the lunar surface temperature varies

greatly between day and night. The maximum

temperature of the lunar surface detected by Apollo

15 at its landing site was 374K and the minimum was

92K. In addition, the lunar surface ultraviolet

radiation and other strong, especially during the solar

storm, the sun's ultraviolet rays directly into, played a

role in eliminating. Second, liquid water has never

been found on the moon's surface. Like the Earth, the

moon is covered with a layer of loose, granular rock

called the lunar regolith. Through the analysis of

lunar exploration and lunar samples, there are

hydrogen enrichment phenomena in the polar regions

of the Moon. The hydrogen enrichment may be

caused by hydrogen injected by the solar wind or

hydroxyl groups contained in some minerals. It may

also be caused by water ice (ice solidified by water or

meltwater at low temperature) mixing with the lunar

soil in the form of fine particles. Liquid water has not

IAMPA 2024 - International Conference on Innovations in Applied Mathematics, Physics and Astronomy

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yet been found on the moon. Finally, lunar soils lack

elements that are currently known to be essential for

carbon-based life. Scholars have analysed the data

obtained by the APXS of the CE3 Yutu lunar rover.

Some typical results of elements are illustrated in Fig.

3, which denote that the lunar soil of the landing site

mainly includes Si, Ca, Al as well as other 10

elements (Guo, et al., 2022). However, it lacks

elements such as C and N, which are essential for life.

So overall, the chances of native life on the moon are

slim. In other words, the possibility of microbial life

on the moon is extremely small.

4.2 Mars

Mars is a great planet to study and a promising

candidate for signs of life, and humans have sent

several landers and rovers to search for evidence of

life. Nevertheless, the planet's barren surface might

actually not the appropriate location for observations

as well as analysis, since telescopes and probes have

proven. Instead, shielded places underground is the

best bet for finding well-preserved evidence of alien

life. However, the nature of these shields makes

detection and detection difficult. Moreover, Mars is

full of caves formed by millennia of lava flows, hence

the caves are difficult to reach and rovers. To address

the issue, NASA worked with collaborators to create

a four-legged, four-legged hiking mechanical utility

robot, or LEMUR. It will allow it to explore areas that

are simply not possible with the rovers currently

exploring the surface of Mars (Joseph et al., 2019).

Some typical detections results based on such scheme

are presented in the left panel of Fig. 4.

In addition to LEMUR, PIXL is also a suite of

rovers onboard the Mars 2020 Perseverance rover to

search for signs of ancient life. The probe's X-ray

Instrument, called PIXL, stands for Planetary

Instrument for X-ray Lithochemistry, and it delivered

surprisingly strong scientific results during testing. It

is used to test the instrument setup and would be

capable of determining the composition of Martian

dust attached to the matters. In addition to analysing

the rock based on the high energy photons, it will

zoom in on tiny fragments of the rock's surface that

could show evidence of past microbial activity. To

obtain a detailed picture of rock texture, contour, and

composition, PIXL maps of rock chemistry can be

combined with mineral maps produced by the

SHERLOC as well as WATSON (Lawson, et al.,

2024). A typical detector diagram and detection

results are shown on the right panel of Fig. 4.

Figure 3: Elements analysis of Moon from the soil sample (data collected from Guo, et al., 2022; Li, et al., 2022).

Probing Life with Planet Searching and Habitat Evaluation: Evidence from Moon, Mars and WASP-96b

141

Figure 4: Probing life on Mars based on typical detectors

(data collected from Joseph et al., 2019; Lawson, et al.,

2024; Mars Nasa and NASA/JPL-Caltech).

4.3 WASP-96b

Hot Saturn WASP-96b is the latest discovery of an

exoplanet atmosphere without clouds, marking a

major breakthrough in the search for planets beyond

our solar system. WASP-96b's atmosphere was

studied by Chile using the European 8.2 Million

Telescope. As a matter of fact, based on the state-of-

art observations for the emission spectrum of WASP-

96b, a complete sodium fingerprint is obtained under

the special circumstance without clouds with a typical

1300K hot gas giant (McGruder, et al., 2022). Earth's

periodic transiting sun-like star is located 980 light-

years in the southern constellation Phoenix, between

the southern jewels (α Austrini) and αEridani. The

presence of sodium of hot gas giant exoplanets has

long been predicted to produce a spectrum similar to

the shape of a camping tent in such special situation.

As the transit method explained earlier (Sec. 2),

when a planet passes in front of a star, blocking some

of the light, some of the starlight is transmitted

through the planet's atmosphere. Because different

components of the atmosphere absorb different

spectra, the observation of subtle differences in

transmitted light can help astronomers determine the

composition of a planet's atmosphere. Being the only

completely cloud-free exoplanet discovered so far,

and showing such a clear spectrum feature for Na

element. So far, sodium has been found to be either a

very narrow peak or missing altogether. This is

because the characteristic "shape" profile can only be

produced deep in a planet's atmosphere, and for most

planets, clouds appear to block its direction. A better

understanding can be gained by looking at a variety

of possible atmospheres similar to WASP-96b

(Radica, et al., 2023). The sodium signature indicates

the absence of clouds in the atmosphere. It will also

provide us with a unique opportunity to determine the

abundance of other molecules. Typical observations

are shown in Fig. 5.

Figure 5: WASP-96b spectrum (data collected from McGruder, et al., 2022; Radica, et al., 2023 and NASA WEBB).

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5 DISCUSSION

As a matter of fact, it should be noted that though

thousands of new planets have been detected based

on advanced techniques and the state-of-art facilities,

no strong evidence or sufficient supporting materials

confirming the existence of Earth 2.0. Whether

human beings are alone in the universe, this is a basic

question that almost everyone wants to know the

answer to, and it is also one of the most cutting-edge

scientific questions that can be solved today. The

search for extraterrestrial life will finally answer this

question. However, the search for extraterrestrial life

must first find the most likely host of life, Earth 2.0.

To date, no Earth 2.0 has been discovered. The first

discovery of Earth 2.0, and subsequent determination

of its habitability through observation of the

atmosphere, will be a major scientific event in the

field of exoplanets. Finding a number of Earth 2.0's

could determine the incidence of such planets,

answering the key question of how common Earth 2.0

is in the universe.

Subsequently, one can determine whether there is

life beyond Earth. The holy grail of the next exoplanet

frontier after the discovery of Earth 2.0 will be the

detection of extraterrestrial life, that is, the detection

of biosignatures produced by life in the atmospheres

of exoplanets to infer the existence of life. This would

answer the fundamental scientific question of

whether there is other life in the universe. There are

two main methods to measure the atmospheric

composition of planets in front of the eye: transit

transmission spectroscopy and direct imaging.

Spectral detection and atmospheric composition

analysis of the atmosphere of Earth-like planets or

super-Earth planets are expected to directly search for

trace gases and compositions released in the

atmosphere of planets by extraterrestrial life activities.

The direct imaging method has become one of the

most important scientific factors driving the

development of new generation ground-based and

space telescopes (e.g., ELT, TMT, GMT), which puts

severe requirements on telescope aperture, adaptive

optics and detector performance.

The detection of planetary atmospheres provides

a crucial constraint for the formation, evolution and

habitability of planets, and is an important means for

the detection of planetary habitability and exolife. By

2030 or so, the next generation of space telescopes

should have high-precision optical spectrometers

capable of detailing the atmospheric composition and

abundance of gas giants, and observing other

properties. The atmospheric composition and

abundance of multiple types of planets accompanying

the evolution of stars are described in detail, and the

atmospheric circulation and atmospheric escape are

studied. Through the accurate measurement of the

tracer gas element abundance and isotope abundance,

it can be related to the important problems of

planetary formation, orbital migration and evolution.

Through the atmospheric modelling of small

exoplanets (e.g., terrestrial planets and super-Earths),

scholars study the transition evolution behaviour

from primary atmosphere to secondary atmosphere,

and the role of atmospheric escape in the habitability

of terrestrial planets. Develop the next generation of

large space telescope (>10m) star coronarometer,

high-contrast direct imaging spectroscopy and optical

interference technology, observe the habitable zone

planets of a large number of neighbouring stars,

confirm whether they are twin Earth from the

planetary reflection spectrum or thermal emission

spectrum, determine their habitability and search for

potential life signs. In addition, as mentioned above,

planetary habitability is an interdisciplinary frontier

research topic. Astronomers are particularly

concerned about the definition of life signals and the

corresponding spectral characteristics, because this is

the key to the future search for extraterrestrial life. At

present, even the JWST can only detect the spectral

characteristics of super-Earths around sun-like stars,

which are larger than the Earth. In the future,

LUVOIR and HabEx hope to use larger telescopes for

direct imaging detection. In order to develop the

space interference and imaging observation of

exoplanets, mankind will search and characterize the

nearby planetary system, expect to obtain the

characteristics of the habitable zone terrestrial planets,

and combine the research on the long-term activity of

stars and the atmospheric model of exoplanets, as

well as the development of interdisciplinary

definition of life signals, etc., to reveal the habitability

of terrestrial planets.

Although international deep space exploration has

flourished in the decades since the launch of the

Voyager spacecraft, almost all current research on

exoplanets is based on passive observation rather than

active exploration. Tiny detectors based on ground-

based laser arrays or accelerated solar radiation called

light sails could change that in the first half of the 21st

century. Tiny probes weighing on the order of grams

will be able to accelerate to solar escape velocity in a

matter of minutes to explore small exoplanets such as'

Oumuamua and analyse their activity, shape, and

composition. With the further miniaturization of

ground-based laser technology and materials science,

as well as chips predicted by Moore's law, it will be

possible for tiny probes to be accelerated to 10

Probing Life with Planet Searching and Habitat Evaluation: Evidence from Moon, Mars and WASP-96b

143

percent of the speed of light, enabling interstellar

travel to reach the solar system's close neighbour, the

alpha Cen system, and image its planets up close for

the first time.

6 CONCLUSION

To sum up, this study systematically analyses the

planet searching schemes as well as habitat evaluation

scenarios and indicators. To give specific examples,

the life searching results of three celestials are detailly

demonstrated and estimated. According to the

analysis, though no life signs have been searched so

far, it is witnessed that the searching tools have been

expanded rapidly with more accurate. Nevertheless, it

should be noted that the current advanced probing

approaches still has some shortcomings, which are

unable to present absolute accurate and direct

information. Further study ought to focus on the

updating of the precise spectrum detectors and signal

extraction as well as collecting direct information and

sample based on machine with collectors. Overall,

these results offer a guideline for further exploration

of Earth 2.0 and exoplanet habitat evaluation.

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