Long Range Reconnaissance Imager


Long Range Reconnaissance Imager is a telescope aboard the New Horizons spacecraft for imaging. LORRI has been used to image Jupiter and its moons and especially Pluto and its system of moons since its launched in 2006. LORRI is a reflecting telescope of Ritchey-Chrétien design, and it has a main mirror diameter of 20.8 cm across. Images are taken with a CCD capturing data with 1024 × 1024 pixels. LORRI is a telescopic panchromatic imager integrated with the New Horizons spacecraft, and it is one of seven major science instruments on the probe. LORRI does not have any moving parts and is pointed by moving the entire New Horizons spacecraft. LORRI has a narrow field of view, less than a third of one degree.

Operations

LORRI was used to calculate albedos for Pluto and Charon. LORRI is also used for navigation, especially to more precisely determine the location of a flyby target. In 2018, New Horizons spacecraft used navigation data from LORRI for its planned flyby of Arrokoth in a couple months.
During the cruise to Jupiter, LORRI data was also used to determine a value for the cosmic optical background as an alternative to other methods. At Jupiter, LORRI was used for an extensive observation campaign of Jupiter's atmosphere, rings, and moons.
On Aug. 29, 2006, the cover on LORRI was opened and it took an image in space of Messier 7 for its first light image. The following year, in 2007 when it flew by Jupiter for its gravity assist, it was used to image Jupiter and its moons. LORRI also imaged the Jovian system in 2010 as part of an Annual Checkout confirming the operation of LORRI, taking pictures from a distance of about 16 AU.
In 2015, LORRI was used to image Pluto before and during the flyby.
In December 2017, NH LORRI took an image at greater distance from Earth than Pale Blue Dot by Voyager 1, in this case of the Wishing Well Cluster.
taken by Voyager 1''.
A large stack of images of Arrokoth from August to December 2018 was used to confirm a closer flyby, rather than more distant by ruling out moons and rings systems to certain level of detection.
On the night of December 24, 2018 LORRI was used to take reconnaissance images of Arrokoth at distance . Three images were taken each with a half second long exposure, at 1024x1024 pixel resolution.

Specifications

LORRi is a reflective telescope integrated with the New Horizons spacecraft, it can take black and white images of astronomical targets.
Specifications:
The mirror is made of material silicon carbide which helped support meeting the thermal requirements of the design.
The detector is a thinned backside-illuminated charge-coupled device, and records 1024 by 1024 pixels, with a variety of exposure settings. LORRI can take one picture per second and store the picture digitally as a 12-bit image, with either lossless or lossy compression.
LORRI incorporates a field-flattening lens, with three elements.
The design can take images at very low light levels required for the mission, including light levels 1/900 those of Earth when it is at Pluto. For the Arrokoth encounter, the longest exposure time, which was up to ten seconds for the Pluto flyby was increased. This was accomplished after the Pluto flyby by the team, to support taking images in even lower light levels.
After the Pluto times, exposure times of at least 30 seconds were made possible, which was also useful for taking reconnaissance images and enabling imaging down to a magnitude of 21. Magnitude in astronomy is way to measure brightness, and higher number is dimmer; two related concepts are Apparent magnitude and Absolute magnitude.
LORRI is pointed by moving the entire spacecraft, which limits the exposure time. The spacecraft does not have reaction wheels and is stabilized by thrusters.

Jovian system

While passing by Jupiter in February 2007, the Jovian system was observed using LORRI and other instruments.
LORRI views of the Galilean moons:

Pluto

Due to its telescope power LORRI was able to capture images of Pluto and its moons, offering the closer views as the spacecraft progressed to the dwarf planet.

Charon

15810 Arawn

In 2016 New Horizons oberved the Kuiper belt object, 15810 Arawn. Arawn is the object that is pointed with an arrow.

486958 Arrokoth

Long-distance views

Approach views

Pluto closest flyby views

Because LORRI had the highest magnification of the instruments, it captured the closest views of Pluto's terrain during the flyby. Its smaller field of view was panned across Pluto, capturing a stripe of the dwarf planet's terrain.