Ralph is a science instrument aboard the robotic ''
New Horizons
''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe that was launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research ...
'' spacecraft, which was launched in 2006.
Ralph is a visible and infrared imager and spectrometer to provide maps of relevant astronomical targets based on data from that hardware.
Ralph has two major subinstruments, LEISA and MVIC. MVIC stands for ''Multispectral Visible Imaging Camera'' and is a color imaging device, while LEISA originally stood for ''Linear Etalon Imaging Spectral Array'' and is an infrared
imaging spectrometer
An imaging spectrometer is an instrument used in hyperspectral imaging and imaging spectroscopy to acquire a spectrally-resolved image of an object or scene, often referred to as a datacube due to the three-dimensional representation of the data. T ...
for spaceflight. LEISA observes 250 discrete
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...
s of
infrared light
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
from 1.25 to 2.5 micrometers. MVIC is a
pushbroom scanner type of design with seven channels, including
red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
,
blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...
, near-infrared (NIR), and
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
.
Overview
Ralph is one of seven major instruments aboard ''New Horizons'' which was launched in 2006 and flew by the dwarf planet
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ...
in 2015.
At Pluto, Ralph enables the observation of many aspects including:
*
geology of Pluto
The geology of Pluto consists of the characteristics of the surface, crust, and interior of Pluto. Because of Pluto's distance from Earth, in-depth study from Earth is difficult. Many details about Pluto remained unknown until 14 July 2015, when ...
*form
*structure
*surface composition
*surface temperature
Ralph and
Alice were used to characterize the
atmosphere of Pluto
The atmosphere of Pluto is the tenuous layer of gases surrounding Pluto. It consists mainly of nitrogen (N2), with minor amounts of methane (CH4) and carbon monoxide (CO), all of which are vaporized from their ices on Pluto's surface. It contain ...
in 2015. Ralph was previously used to observe the planet
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
and its moons in 2006 and in 2007 when it flew-by en route out of the
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 ...
and past Pluto.
Observations of
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
were taken with Ralph in February 2007, when ''New Horizons'' was about 6 million kilometers (nearly 4 million miles) from the giant.
Ralph took color images of
Arrokoth during the ''New Horizons'' flyby on January 1, 2019. Ralph, in conjunction with the LORRI telescope, was used to make a digital elevation map of the body.
A version of Ralph is carried on
''Lucy'', which is visiting six
Jupiter trojan
The Jupiter trojans, commonly called trojan asteroids or simply trojans, are a large group of asteroids that share the planet Jupiter's orbit around the Sun. Relative to Jupiter, each trojan librates around one of Jupiter's stable Lagrange poin ...
s and an
asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere.
...
in the 2020s.
The developers of that spacecraft noted in particular Ralph's ability to observe visible and infrared light by splitting the light stream, and then analyze two spectrums of light at the same time.
Naming
Ralph is named after a character in the 1950s television show ''
The Honeymooners
''The Honeymooners'' is an American television sitcom which originally aired from 1955 to 1956, created by and starring Jackie Gleason, and based on a recurring comedy sketch of the same name that had been part of Gleason's variety show. It fol ...
'', along with another ''New Horizons'' instrument,
Alice.
LEISA's acronym was retitled from ''Linear Etalon Imaging Spectral Array'' to ''Lisa Hardaway Infrared Mapping Spectrometer'' by NASA in June 2017, after Ralph's program manager.
Lisa Hardaway was an aerospace engineer and ''New Horizons'' Ralph instrument program manager who died in January 2017 at the age of 50. Hardaway was honored with Engineer of the Year for 2015–2016 by the American Institute of Aeronautics and Astronautics (Rocky Mountain Section) and Women in Aerospace organization awarded her a leadership award in 2015. In the summer of 2017, NASA renamed the LEISA channel in her honor.
Methane observations
An example of Ralph's abilities is shown by this detection of
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
on the surface of Pluto (left), overlaid on an image from
LORRI Lorri may refer to:
Acronym
* LORRI, the Long Range Reconnaissance Imager, a camera on board the ''New Horizons'' spacecraft
Given name
* Lorri Bagley, an American actress and model
* Lorri Jean, a leader in the gay, lesbian, bisexual and transg ...
on the right:
In 2018 it was announced, based on ''New Horizons'' high resolution data, that some of the plains of Pluto have dunes made of methane ice granules. The dunes are thought to have been formed by the blowing winds of Pluto, which are not as dense as those of Earth, and were compared to Dunes elsewhere in the Solar System such as on Saturn's moon
Titan.
Specifications
Specifications:
[Ralph: A Visible/Infrared Imager for the New Horizons Pluto/Kuiper Belt Mission](_blank)
/ref>
*Mass:
*Max power use: 7.1 watts
*Telescope design
**Unobscured
** Off-axis
**Three-mirror anastigmat
A three-mirror anastigmat is an anastigmat telescope built with three curved mirrors, enabling it to minimize all three main optical aberrations – spherical aberration, coma, and astigmatism. This is primarily used to enable wide fields of view, ...
*Aperture 75 mm[Ralph: A Visible/Infrared Imager for the New Horizons Pluto/Kuiper Belt Mission](_blank)
/ref>
** f/8.7
**Effective focal length
The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...
658 mm
*Electronic control boards
**Detector electronics (DE)
**Command and data handling (C&DH)
**Low voltage power supply (LVPS)
The one telescope feeds light to both LEISA and MVIC channels, with light split by a dichroic beamsplitter
A beam splitter or ''beamsplitter'' is an optical device that splits a beam of light into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding wide ...
.
*MVIC detects light between 400 and 975 nm wavelengths
*LEISA detects light between 1250 and 2500 nm wavelengths
MVIC has seven CCDs that are wide but short, utilizing time-delay integration to read the imaging area. These channels have a resolution of 5024×32 pixels, with the larger direction providing the swath of the image. There are seven channels, with 6 used for time delay integration imaging and the seventh with an array of 5024×128 for navigation framing. MVIC has a field of view that is 5.8 degrees wide The framing channel, with 5024×128 pixel size, is panchromatic and a field of view of 5.7 degrees × 0.15 degrees. Unlike the other six channels, it can stare at one target and take an image. The purpose of this channel is to support optical navigation.[http://www.boulder.swri.edu/pkb/ssr/ssr-ralph.pdf ] The Navigation channel is a Frame array that operates as a single frame, rather than the other channels which generate an image by time delay integration.
MVIC Bands: There are six channels that use Time Delay Integration and another that takes a frame and is for navigation.
*2 panchromatic channels (observing light wavelengths from 400 to 975 nm)
*Blue
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...
(400–550 nm)
*Red
Red is the color at the long wavelength end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and a secondar ...
(540–700 nm)
*Near infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
(from 780 up to 975 nm light wavelengths)
*methane band (860–910 nm)
*Navigation channel / framing array
LEISA achieved its highest resolution data of Pluto of about 3 km/pixel at ''New Horizon''s closest approach to Pluto on July 14, 2015, when it was 47,000 km distant."Highest Spatial Resolution New Horizons Leisa Spectral-Imaging Scan of Pluto"
/ref>
Images
During the flyby of Pluto on July 14, 2015, Ralph was able to collect data on Pluto and its moons yielding various image results. In addition, the MVIC color channels were often the source of color on the otherwise panchromatic LORRI images.
486958 Arrokoth
See also
*UVS
Uvs (; mn, Увс аймаг, Uws aimag, ; xal, Увс әәмг, Uws äämg, ), is one of the 21 aimags (provinces) of Mongolia. It is located in the west of the country, away from the national capital Ulaanbaatar. Its capital is Ulaangom whi ...
(Ultraviolet imaging spectrometer on ''Juno'' Jupiter orbiter)
*Jovian Infrared Auroral Mapper
Jovian Infrared Auroral Mapper (JIRAM) is an instrument on the ''Juno'' spacecraft in orbit of the planet Jupiter. It is an image spectrometer and was contributed by Italy. Similar instruments are on ESA ''Rosetta'', ''Venus Express'', and '' C ...
(Infrared imaging on ''Juno'' orbiter)
*Compact Reconnaissance Imaging Spectrometer for Mars
The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is a visible-infrared spectrometer aboard the Mars Reconnaissance Orbiter searching for mineralogic indications of past and present water on Mars. The CRISM instrument team compris ...
(CRISM, an imaging spectrometer in Mars orbit)
* List of ''New Horizons'' topics
Notes
References
External links
''New Horizons Insturments (NASA)
NASA - Ralph
{{Satellite and spacecraft instruments
New Horizons
Spacecraft instruments