NASA has selected two finalists for consideration as the next New Frontiers mission: a comet sample return and a flying drone for Titan.

CAESAR approaches Comet 67/P Churyumov-Gerasimenko for sample collection in this artist's conception.

What's on your Christmas wish list? NASA managers released theirs on Wednesday, announcing the finalists for what will become the space agency's fourth New Frontiers mission in the coming decade.

NASA will either return to a comet first explored by the European Space Agency for an ambitious sample return — or send a nuclear-powered quadcopter to fly through the methane-choked skies of Saturn's moon Titan.

“This is a giant leap forward in developing our next bold mission of science discovery,” says Thomas Zurbuchen (head of NASA's Science Mission Directorate) in a recent press release. “These are tantalizing investigations that seek to answer some of the biggest questions in our solar system today.”

Finalist #1: Dragonfly

First up: Dragonfly. This dual quadcopter drone would explore various sites on Titan. Dragonfly would make use of the moon's dense atmosphere, flying from site to site to sample prebiotic chemistry on the surface. Titan's the best place in the solar system to fly a quadcopter, with an atmosphere four times as dense as our own and surface gravity only a seventh of Earth's.

Dragonfly is ambitious. It won't employ an orbiter for relay, instead relying on direct communications from the surface of Titan.

Principal Investigator Elizabeth Turtle also stated in Wednesday's press conference that a small Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) utilizing plutonium-238 will power Dragonfly. This is essential, as using solar power isn't possible on the cloud-shrouded moon. The U.S. Department of Energy restarted its plutonium-238 production pipeline for NASA in 2013. NASA has a classified but limited supply of plutonium, some of which is earmarked for the Mars 2020 rover.

Dragonfly titan
An artist's conception of the Dragonfly drone exploring Titan.

Dragonfly's science package includes a mass spectrometer, a drill and sampling package, gamma-ray and neutron spectrometers, and a geophysics and meteorology package. If approved, Johns Hopkins University Applied Physics Laboratory (JHU-APL) would manage the project, with Dragonfly launching in 2025 and arriving at Titan in 2034. .

Finalist #2: CAESAR

Comet 67P
Will CAESAR return to the strange world (pictured here) of Comet 67P Churyumov-Gerasimenko?
ESA / Rosetta

The second contender, called Comet Astrobiology Exploration Sample Return (CAESAR), would perform an in-depth analysis and sample return from a comet, returning to the comet explored by the European Space Agency's Rosetta mission, 67/P Churyumov-Gerasimenko. The Rosetta orbiter explored and mapped the periodic comet in detail, which will help the team select a collection site far in advance of arrival. CAESAR would collect 100 grams or more of volatile and non-volatile material from the comet for return to Earth.

The Japan Aerospace Exploration Agency (JAXA) would provide the sample return capsule. It's essential to keep the volatile components of the return sample cold, so they don't evaporate before they can be studied. A design similar to JAXA's Hayabusa return capsule is desirable, which dropped its heat shield after reentry, before heat could begin transferring to the inner capsule.

The return of CAESAR's sample to Earth would occur on November 20, 2038, over the Utah Test and Training Range, the same site where Stardust and the ill-fated Genesis spacecraft returned from interplanetary space with their samples.

NASA's Goddard Space Flight Center will manage the mission, and Orbital ATK will build the CAESAR spacecraft.

Runner-Ups: Ocean Worlds and Venus Explorer

NASA also selected two concepts for enhanced technology development:

  • Venus In-Situ Composition Investigations (VICI): This program will further develop the Venus Element and Mineralogy Camera for operation on the harsh surface of Venus. Lori Glaze (NASA Goddard) is the principle investigator for VICI.
  • Enceladus Life Signatures and Habitability (ELSAH): Managed by the Goddard Spaceflight Center, ELSAH will look at cost-effective ways to limit spacecraft contamination on low-budget missions. The principal investigator for ELSAH is Chris McKay (NASA Ames).

Other mission concepts that were in the running included:

  • Titan Oceanus: a Titan orbiter that would study the creation of complex organic molecules by skimming through the big moon's upper atmosphere
  • Lunar South Pole-Aitken Basin Sample Return: this ambitious plan would have sent a lander to the lunar farside  to provide geochemists with material excavated from the Moon's largest impact basin.
  • Saturn Probe Interior and Atmosphere Explorer (SPRITE) would have picked up where Cassini left off on its final orbits, probing the deep interior of Saturn and measuring the planet's hydrogen and helium ratio.

NASA Budget

NASA's budget received a $1.3 billion boost, to $19.3 billion, back in fiscal year 2016, and Congress proposed a $19.5 billion dollar budget for NASA for fiscal year 2018. Of that, $1.61 billion is earmarked for planetary exploration, a drop from 2017 but on level with 2016 amounts.

NASA conducts three basic types of planetary missions. Flagship missions cost more than $1 billion. Examples include Curiosity, Cassini and, if funded, the Uranus and/or Neptune orbiter mission for the 2030s. New Frontiers missions are mid-cost, capped at $1 billion. New Frontiers alumni include the New Horizons mission to Pluto and beyond, the Dawn mission to 4 Vesta and 1 Ceres, and the Osiris-REX mission to asteroid 101955 Bennu. Discovery missions are low-cost, capped around $450 to $600 million dollars. The upcoming Lucy and Psyche asteroid missions are Discovery class.

The Timeline

The finalists will now move on to Phase A concept evaluation over the next year. Both teams will submit a final mission proposal by late January 2019. The final mission selection is set for July 2019, after which the winner will move ahead with development and launch around 2025.

The next New Frontiers mission will either use an existing launch carrier, such as the Atlas V rocket, or a new-generation heavy-lift rocket, such as NASA's SLS or SpaceX's Falcon 9 Heavy. Elon Musk just revealed the Falcon 9 Heavy this week, possibly set for its long awaited inaugural flight from the Kennedy Space Center in January. The first flight of SLS is set for 2019.

Falcon 9 Heavy
Falcon 9 (times three) Falcon Heavy revealed for a January 2018 launch.
SpaceX / Elon Musk

Either mission would be exciting. The ESA Huygens spacecraft, for example, only lasted a very brief few hours on the surface of Titan in 2005, but Dragonfly could last for years. Likewise for the proposed return to Rosetta's comet. Hey, maybe we'll get a view of Rosetta, sitting derelict on the comet's surface? Or maybe Dragonfly will give us a look at noble Huygens, half-buried on the surface of Titan?

Though the time frames are long, it's encouraging to see new missions planned for a return to the outer solar system in the coming decade.


Image of Jim-Baughman


December 23, 2017 at 1:16 am

I vote for Dragonfly. There are more mysteries on Titan I think than on a comet, plus Dragonfly should allow us to map Titan's surface and track its weather over long periods...perhaps even image an ethane "rain" storm in progress.

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Image of mxyzptlk


December 25, 2017 at 9:41 pm

How can there be any doubt that Dragonfly would be the right choice? It means science will be conducted and returned in REAL TIME. The potential discoveries are mind-boggling. A cometary sample return mission is a complete (for me) YAWNER !

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