![Galileo Probe - AC81-0174](https://upload.wikimedia.org/wikipedia/commons/d/d3/Galileo_Probe_-_AC81-0174.jpg)
The Saturn Atmospheric Entry Probe is a mission concept study for a robotic
spacecraft
A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, p ...
to deliver a single probe into
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
to study its atmosphere. The concept study was done to support the NASA 2010
Planetary Science Decadal Survey
The Planetary Science Decadal Survey is a publication of the United States National Research Council produced for NASA and other United States Government Agencies such as the National Science Foundation.National Academy of Sciences, National Acade ...
[ (Archived from the original).]
Due to the orbits and relative positions of Saturn and Earth, launch was proposed for 30 August 2027 for a 22 June 2034 arrival.
The mission was studied for the NASA
Planetary Science Decadal Survey
The Planetary Science Decadal Survey is a publication of the United States National Research Council produced for NASA and other United States Government Agencies such as the National Science Foundation.National Academy of Sciences, National Acade ...
as a possible NASA
New Frontiers-class mission.
Overview
![Saturn, Earth size comparison](https://upload.wikimedia.org/wikipedia/commons/3/39/Saturn%2C_Earth_size_comparison.jpg)
To unveil the processes of outer planet formation and
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
evolution, detailed studies of the composition, structure, and dynamics of giant planet interiors and atmospheres would be necessary. To constrain the internal structure of
gas giant
A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" ...
s, a combination of both ''
in-situ'' entry-probe missions and remote-sensing studies of the giant planets would be needed.
The Saturn Atmospheric Entry Probe mission would consist of a carrier-relay spacecraft and a probe. The carrier-relay spacecraft would release the probe into Saturn, a gas giant, and provide data relay from the probe to Earth. The probe would determine the structure of the atmosphere as well as
noble gas
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemi ...
abundances and
isotopic ratios of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
,
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
,
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
.
Objectives
* determine the
noble gas
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemi ...
abundances and
isotopic ratios of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
,
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
,
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
,
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
, and
argon
Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...
in Saturn's atmosphere.
* determine the atmospheric structure at the probe descent location.
Tier 2 objectives include:
Scientific Value of a Saturn Atmospheric Probe Mission
(PDF) D. H. Atkinson. NASA, 2012.
* determine the vertical profile of zonal winds as a function of depth at the probe entry location;
* determine the location, density, and composition of clouds as a function of depth in the atmosphere;
* determine variability of atmospheric structure and the presence of clouds at the location;
* determine the vertical water abundance profile at the probe descent location;
* make precision isotope measurements for light elements (e.g. S, N, O) in atmospheric constituents.
Scientific payload
In order to complete its objectives, the probe must carry at least these two instruments:
* a mass spectrometer
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...
(MS); it would determine the noble gas
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemi ...
abundances and isotopic ratios of H, C, N, O, and Ar in Saturn's atmosphere.
* an atmospheric structure instrument (ASI); based on the ''Galileo'' probe design, it would consist of three sensors for measuring temperature, pressure, and density.
Timeline
Launch and trajectory
Launch is proposed for 30 August 2027. After launch, the spacecraft would enter heliocentric orbit and be placed on a trajectory to fly by the Earth, which is proposed to take place on 16 July 2030 at a distance of 300 km. After that, the spacecraft would spend 4 years traveling to Saturn.
Approach and targeting phase
This phase would begin 8 months before arrival. The probe would separate from carrier–relay spacecraft and free-fall into Saturn's atmosphere.
Science phase
Hours before the probe's entry, the science phase would begin. An event timer on the probe would initiate activities, while the carrier–relay spacecraft would power up its radio receiver and turn to point its probe-relay antenna to the entry site. The probe would enter Saturn's atmosphere at a velocity of approximately 27 km/s, which is less than the ''Galileo'' Probe's velocity of 47.4 km/s. After the entry heating and deceleration phase, the probe would deploy a drogue parachute and then the main parachute when it reached an atmospheric pressure of 0.1 bar. At 1 bar of pressure, the parachute would be released and the descent module would continue free-falling through the atmosphere (possibly with stabilization from another drogue parachute) to the nominal end of mission, 55 minutes after entry and 250 km deep. The probe would be designed to endure at least 10 bars of pressure.
Downlink of data, flyby of Saturn and end of mission
Shortly after data relay ends, downlink of data would begin. The data set measured by the probe would be about approximately 2 Mb, so 20 minutes would be need to complete the data downlink. The carrier–relay spacecraft would fly by Saturn at a distance of approximately 100 Mm and it would continue on a solar escape trajectory.
Mission Proposal
Following the concept study done to support the NASA Decadal Survey, the Saturn Atmospheric Entry probe concept was further developed into a mission concept, which was proposed under the name SPRITE ("Saturn PRobe Interior and aTmospheric Explorer") to the NASA New Frontiers program
The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of furthering the understanding of the Solar System. The program selects medium-class missions which can provide high science returns.
...
solicitation in 2016.
References
{{NASA navbox
Missions to Saturn
Extraterrestrial atmosphere entry
New Frontiers program proposals