The Telescopes on New Horizons – Big Science with Small Instruments

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Today marks the 11 year anniversary of the New Horizons launch. It was in July 2015 that the New Horizons spacecraft flew by Pluto, giving us our first close look at a surprisingly diverse world. But did you know that one of the telescopes onboard New Horizons isn’t that different from what you can buy yourself?

One of the many things I find really interesting about this mission, is one of the two imaging instruments, LORRI, is not that disimilar from what amateur astronomers use on Earth.

There are two primary optical instruments on New Horizons, RALPH, and LORRI, that are both worth a quick look.


The lens of the RALPH instrument is a 75mm aperture telescope with a focal length of 658mm. Despite the relatively moderate aperture of this instrument, it’s hard to really equate it to amateur gear since it’s very much a custom instrument that feeds multiple detectors. The instrument is so named because it’s coupled with an ultraviolet spectrometer called Alice in the New Horizons remote-sensing package – a reference familiar to fans of “The Honeymooners” TV show.


While Ralph is a custom affair, LORRI is very much in the realm of the amateur astronomer! The Long Range Reconnaissance Imager is an 8.2 inch aperture Ritchey-Chrétien f/12.6 telescope connected to a 1024×1024 px CCD camera. If you happen to have an 8″ RC telescope, you’re using an instrument not that different from what is flying beyond Pluto right now! (And such telescopes start at under $1000.)

As JPL explains it: LORRI, the “eagle eyes” of New Horizons, is a panchromatic high-magnification imager, consisting of a telescope with an 8.2-inch (20.8-centimeter) aperture that focuses visible light onto a charge-coupled device (CCD). It’s essentially a digital camera with a large telephoto telescope – only fortified to operate in the cold, hostile environs near Pluto.

An 8″ RC is literally on off the shelf purchase (though it won’t be space rated, of course).

Orion sells an 8″ F/8 RC for $999, and a 6″ f/9 RC for $499. Similarly a Mono CCD can be purchased for under $1000. Put it on a good mount, you have your own little LORRI!

More Details

The SouthWest Research Institute has detailed PDFs about the two instruments, including design specs, and various photographs. If you’re a spacecraft/telescope geek, these are worth at least a skim through!

Off The Shelf Instruments in Real Science

DragonFly Array

DragonFly Array

The main point here is really that the distinction between amateur and professional instruments is getting smaller as optical and manufacturing technologies continue getting better. Many professional astronomers are starting to look to off the shelf lenses and sensors to control costs while still achieving their research goals. A great example of this is the Project Dragonfly, which uses standard Canon camera lenses for an effective f/0.9 array designed to look for very faint low surface brightness targets. While still expensive (each 400mm lens is $10,000) this is far cheaper than building a custom instrument from scratch! (Here’s a presentation about the science being done with the DragonFly.)

The proliferation of inexpensive cameras and telescopes also starts to open up the possibility of more citizen science efforts.

A Slate article by Phil Plate in 2014 discussed how larger exoplanet transits can be detected with nothing larger than a 300mm camera lens (Detecting an Exoplanet … Without a Telescope).


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