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Van Kane

Selecting the Next New Frontiers Mission

Posted by Van Kane

29-08-2016 8:09 CDT

Topics: Future Mission Concepts

This article originally appeared on Van Kane's website and is reposted here with permission.

NASA’s managers have begun the process for a competition to select a new planetary mission to launch in the mid-2020s that will address one of the most important questions in planetary science. The winning proposal will be the fourth mission in the agency’s New Frontiers program, which sent the New Horizons craft to Pluto, the Juno orbiter to Jupiter, and will launch the OSIRIS-REx mission next month to return a sample from a primitive asteroid.

Previously selected New Frontiers missions


Previously selected New Frontiers missions

NASA’s planetary missions fall into three categories of ambition and cost. At the high end at around $2-2.5 billion are the Flagship missions that use highly capable spacecraft for exploration that addresses a wide range of questions at the target world. These missions include the Curiosity Mars rover, its 2020 Mars rover sibling in development, and the planned Europa multi-flyby mission. 

At the low end, at around $600 million, are the Discovery missions that conduct highly focused missions. Teams are free to propose missions to study any solar system body except the Sun and Earth (which are studied through other programs at NASA). Ten of these planetary missions have flown successfully and have included the MESSENGER spacecraft that orbited Mercury and the Dawn spacecraft that currently orbits the asteroid Ceres. Next up will be the 2018 InSight geophysical station for Mars to be followed by one or two missions to study either asteroids and/or Venus that will be selected by the end of the year.

At a total cost of somewhere around $1 billion, the New Frontiers missions fit between these two programs in ambition. The goal for these missions are to address focused high priority science questions. The scientific community selects the candidate themes through the Decadal Survey in which a long list of scientist-proposed ideas are vetted and prioritized. 

The next New Frontiers mission will be selected from among a list of the six mission themes that the planetary science community identified as highest priority to answer key questions about our solar system:

  • Comet Surface Sample Return – Enable in-depth laboratory analysis of the most primitive material left form the formation of the solar system
  • Lunar South Pole-Aitken Basin Sample Return – Enable in-depth laboratory analysis of material from our moon to understand the how the bombardment of the inner solar system worlds by comets and asteroids effected their formation
  • Saturn Atmospheric Probe – Determine the composition of Saturn’s atmosphere to help us better understand the formation of the solar system
  • Trojan Asteroid Tour and Rendezvous – Explore a reservoir of remnant bodies from the formation of the solar system to understand how materials from different regions of the early solar system mixed during planetary formation
  • Venus In Situ Explorer – Understand the formation, evolution, and current state of the atmosphere and surface of our sister world that evolved into a hell
  • Ocean Worlds (Titan and/or Enceladus) – Do these two moons of Saturn have the conditions to support life and is life present?

The first five of these themes were selected through the Decadal Survey. NASA’s managers added the Ocean Worlds theme in response to a Congressional directive and further discoveries by the Cassini mission. For the next, fifth New Frontiers competition, Jupiter’s moon Io and a lunar geophysical network theme will be added.

NASA’s managers currently expect to select a New Frontiers mission from the list of themes approximately every five years. At that pace, completing this series of investigations, including the new themes for the next selection, will require around forty years (assuming no changes to the list from future Decadal Surveys). The pressure on each proposing team to have their proposal selected now rather than waiting decades must be intense. (If this long time frame seems disheartening, some of the themes may be addressed by other space agencies. A European team, for example, is proposing a Saturn atmospheric probe to the European Space Agency. NASA Discovery missions may also partially address some of the themes. Among the five proposals competing to be among the next Discovery missions are spacecraft that would address several of the atmospheric objectives of the Venus theme and address the Trojan theme through flybys rather than the proposed New Frontiers orbiter plus flybys approach.)

For some of the themes, the Decadal Survey listed (and NASA’s managers have adopted) very specific research goals. Any team proposing a mission for the Venus in situ explorer, for example, must propose a probe that would descend through the atmosphere and likely land on the surface. Here are the objectives from the draft document announcing NASA’s request for proposals (called an Announcement of Opportunity (AO)):

The Venus In Situ Explorer mission theme is focused on examining the physics and chemistry of Venus’s atmosphere and crust by characterizing variables that cannot be measured from orbit, including the detailed composition of the lower atmosphere, and the elemental and mineralogical composition of surface materials. The science objectives (listed without priority) of this mission theme are:

  • Understand the physics and chemistry of Venus’s atmosphere through measurement of its composition, especially the abundances of sulfur, trace gases, light stable isotopes, and noble-gas isotopes;
  • Constrain the coupling of thermochemical, photochemical, and dynamical processes in Venus’s atmosphere and between the surface and atmosphere to understand radiative balance, climate, dynamics, and chemical cycles;
  • Understand the physics and chemistry of Venus’s crust;
  • Understand the properties of Venus’s atmosphere down to the surface and improve understanding of Venus’s zonal cloud-level winds;
  • Understand the weathering environment of the crust of Venus in the context of the dynamics of the atmosphere of Venus and the composition and texture of its surface materials; and
  • Search for evidence of past hydrological cycles, oceans, and life and constraints on the evolution of Venus’s atmosphere.

This is an ambitious list, and the AO specifically states that proposers can select, but must thoroughly justify their selection, a subset of these goals.

By contrast, the goals for the Trojan asteroid tour and rendezvous reflect the fact that we know very little about these never-visited bodies that share Jupiter’s orbit. This population of small worlds represents fragments left over from the formation of the planets. The diversity of the composition of these worlds will allow scientists to select from among competing models for how the solar system formed. The requirements for this theme are short:

The Trojan Tour and Rendezvous mission theme is intended to examine two or more small bodies sharing the orbit of Jupiter, including one or more flybys followed by an extended rendezvous with a Trojan object. The science objective of this mission theme is:

  • Visit, observe, and characterize multiple Trojan asteroids

The briefness of the requirements for the Trojan theme likely makes life harder for teams proposing a mission to these worlds. In judging proposals, NASA’s review teams will score proposals on their scientific merit (~40% of score), the feasibility of the specific proposed instruments and measurements (~30%), and overall mission feasibility within the cost cap (~30%). Scientific merit includes an explanation of the, “Compelling nature and scientific priority of the proposed investigation's science goals and objectives. This factor includes the clarity of the goals and objectives…” Teams proposing for Venus have the benefit of goals developed and specified by the Venus science community while teams proposing for the Trojans have to develop and defend their own list of specific science goals and objectives. (At the end of this post, I’ve copied the specific goals for the remaining mission themes from the AO.)

Missions proposed for the next New Frontiers program will need to meet many criteria including these:

  • Total cost for the development of the spacecraft, the instruments, and analysis of the returned data cannot exceed $850 million. NASA will separately pay for the mission’s launch and operation costs while in flight (likely several tens of millions of dollars per year), which together probably will bring the total cost of the mission to $1 billion or more. 
  • Proposals can include instruments paid for by foreign governments, but the costs of these instruments cannot exceed one-third of the cost of the total instrument compliment. As one NASA manager put it, NASA invests a great deal of money to develop instrument technologies by American scientists, and it wants to see a return on that investment by having the majority of instruments on the selected mission be American. 
  • Teams can propose the use of radioisotope heaters and radioisotope electrical power generators for their missions. These units would be useful for missions operating far from the sun (for example, at Saturn). However, a mission using these units would need to reserve a substantial portion of the core $850 million to cover the cost of these units. Using just the heaters would incur a cost of $47-79 million (depending on the number) and the electrical power generators would cost $133-195 million (again based on the number of generators used). These costs could drastically reduce the capabilities of the spacecraft and instruments compared to missions that don’t require these technologies.

I suspect that for many readers of this blog, a mission to return to Enceladus or Titan to continue their exploration with a new generation of spacecraft and instruments would be a personal favorite. I share that desire, but also recognize the challenges any proposal to these worlds would face. First, these worlds were just added to the list of candidate themes in the past few months. The in-depth analysis of objectives for these missions is just getting underway by the scientific community. Second, the technical maturity of instruments to explore their oceans, determine their habitability, and search for life may be low – NASA has not made major investments in these technologies for these worlds (but plans to begin to do so). And third, these missions are likely to need radioisotope power generators and their cost would eat significantly into the mission budget, potentially making it less competitive. (Solar powered missions are possible at Saturn, but appear to be on the edge technically. This could make a proposal that depends on solar power appear technically risky.) Balancing these negatives is a heritage of three Discovery-class proposals to these worlds that were not selected but which could form the basis of a New Frontiers-class mission. Still, I personally doubt that a mission to these moons will be selected this time. (If I am wrong, given a mid-2020’s launch and a flight that could last 10 years, it could be the mid-2030s before the spacecraft arrives at its target.)

I’ve learned to not try to predict which Discovery or New Frontiers mission is likely to be selected from the list of proposals made. The scrutiny given these proposals is intense. Any fault with the details of a proposal can rule it out. If the review panel decides that a proposed key engineering manager doesn’t have sufficient experience, that could kill a proposal. If the review panel concludes that a technology proposed to be used for the spacecraft or a key instrument lacks maturity, that could kill a proposal. If the review panel concludes that the specific set of scientific objectives proposed are not as compelling as for other proposals, that could kill a proposal. No matter how sexy a proposal might look from the limited information that we in the general public get to see, faults in the details that we never see may rule it out.

However, we need to remember that all the candidate themes for the upcoming selection of the fourth New Frontiers mission represent questions deemed to be among the highest priority for exploring the solar system. Whichever mission is finally selected will significantly expand our understanding of the solar system.

Schedule for the next New Frontiers competition and launch:

  • Final AO Release Date -- January 2017 (target)
  • Deadline for Receipt of Proposals -- AO Release + 3 months + 4 days
  • Selection of a subset (historically, two) of proposals for further study -- November 2017 (AO release + 10 months)
  • Final selection -- July 2019 (target)
  • Launch -- December 31, 2024 if solar powered or December 31, 2025 if radioisotope power sources are required
  • Flight time to the target world: Days (the moon), months (Venus), years to a decade or more (comet with Earth return, Saturn, or Trojan asteroids)

Science goals for the remaining mission themes (goals for the Venus and Trojan asteroid themes listed above):

The Comet Surface Sample Return mission theme is focused on acquiring and returning to Earth a macroscopic sample from the surface of a comet nucleus using a sampling technique that preserves organic material in the sample. The mission theme would also use additional instrumentation on the spacecraft to determine the geologic and geomorphologic context of the sampled region. Because of the increasingly blurred distinction between comets and the most primitive asteroids, many important objectives of an asteroid sample return mission could also be accomplished by this mission. The science objectives (listed without priority) of this mission theme are.

  • Acquire and return to Earth for laboratory analysis a macroscopic comet nucleus surface sample;
  • Characterize the surface region sampled; and
  • Preserve sample complex organics.

The Lunar South Pole-Aitken Basin Sample Return mission theme is focused on returning samples from this ancient and deeply excavated impact basin to Earth for characterization and study. In addition to returning samples, this mission would also document the geologic context of the landing site. The science objectives (listed without priority) of this mission theme are:

  • Elucidate the nature of the Moon’s lower crust and/or mantle by direct measurements of its composition and of sample ages;
  • Determine the chronology of basin-forming impacts and constrain the period of late, heavy bombardment in the inner solar system, and thus, address fundamental questions of inner solar system impact processes and chronology;
  • Characterize a large lunar impact basin through “ground truth” validation of global, regional, and local remotely sensed data of the sampled site;
  • Elucidate the sources of thorium and other heat-producing elements to understand lunar differentiation and thermal evolution; and
  • Determine the age and composition of farside basalts to determine how mantle source regions on the Moon’s farside differ from the basalts from regions sampled by Apollo and Luna

The Ocean Worlds mission theme is focused on the search for signs of extant life and/or characterizing the potential habitability of Titan and/or Enceladus. For Enceladus, the science objectives (listed without priority) of this mission theme are:

  • Assess the habitability of Enceladus’ ocean; and
  • Search for signs of biosignatures and/or evidence of extant life.
  • For Titan, the science objectives (listed without priority) of the Ocean Worlds mission theme are:
  • Understand the organic and methanogenic cycle on Titan, especially as it relates to prebiotic chemistry; and
  • Investigate the subsurface ocean and/or liquid reservoirs, particularly their evolution and possible interaction with the surface.

The Saturn Probe mission theme is intended to deploy one or more probes into Saturn’s atmosphere to directly determine the structure of the atmosphere as well as noble gas abundances and isotopic ratios of hydrogen, carbon, nitrogen, and oxygen. The science objectives (listed without priority) of this mission theme are:

  • Determine noble gas abundances and isotopic ratios of hydrogen, carbon, nitrogen, and oxygen in Saturn’s atmosphere; and
  • Determine the atmospheric structure at the probe descent location.
See other posts from August 2016


Or read more blog entries about: Future Mission Concepts


David Frankis: 08/29/2016 02:45 CDT

As you say, some of the shortlisted Discovery missions would partially meet the New Frontiers objectives. If DAVINCI or Lucy is selected, would that affect the evaluation of VISE or the Trojan tour and Rendezvous?

Karl Norton: 08/30/2016 04:51 CDT

With regards to a Saturn Probe mission isn't Cassini's final dive into the Saturn atmosphere providing the same data set? It is interesting that only Saturn's atmosphere was considered for study, why not the other outer planets? (Uranus or Neptune) Would these worlds only be considered for a Flagship mission?

Karen: 08/30/2016 04:54 CDT

Always such a painful process to watch and such a shame that funding is always so lacking. Ocean Worlds really sounds more like a flagship to me. It's not going to be for a long time anyway, what's a bit more delay? It has enough broad appeal to actually win a flagship competition. And oh, how marvelous such a mission could be on a flagship budget! As a Venus fan, that would be my preference, but I find the requirements frustrating. In my view, the most important thing we can do is a long-term in-situ data-gathering project bobbing between the middle/upper cloud and the upper haze layer. This would let us validate so much that is really critical for future missions (long term materials survivability, larger-scale inflation techniques, permeability in Venus conditions, long-term weather variance, precip., lightning, etc), as well as regularly getting under that thick lower cloud deck for long wave surface observations. But what they're proposing a modern Venera :Þ Even going to the same type of MORB plains that Venera did, rather than the vastly more interesting highlands. Aka the place that looks to have (multiple?) types of (metallic?) (snows? frosts?) and could represent old crust, even granite - a critical factor toward understanding the evolution of Venus. At least there is a balloon element, albeit for only 3,5 days, aka not much better than Vega. So little new ground being pushed :( They almost certainly won't test new inflation / deceleration techniques, like ballutes, but will probably at least trial modern materials (for super short periods of time :Þ) - not just a repeat of Vega's PTFE. They might be able to answer questions about whether precipitation or condensation accumulates at different layers, which is a really major thing to know that Vega left ambiguous. But with such a short flight time it'll be hard to call anything it gathers conclusive as to the general nature of Venus's cloud deck.

Stephen: 08/30/2016 07:26 CDT

“Launch -- December 31, 2024 if solar powered or December 31, 2025 if radioisotope power sources are required” Are those launch dates correct? 2024 is more than eight years away! NASA built the entire Apollo program from the ground up AND landed a man on the Moon in only eight years (counting from Kennedy’s speech on May 1961 until July 1969). During that time there were five complete Apollo missions, including three which went to the Moon. To add insult to injury while the teams only get 3 months & 4 days to send in their proposals after the AO release NASA will take more than two YEARS just to make up their minds which mission will get the nod! The word “glacial” springs to mind, but even glaciers probably move at a more sprightly pace! It also raises a question: what is the schedule for New Frontiers 5? Or am I being too ambitious and we will have wait until NF 4 is launched before NASA gets around to thinking about the next one?

martinselvis: 08/30/2016 08:03 CDT

Decades long programs are not serious about exploring the Solar System. There is a way out. In a recent, rather long, paper (, section 3.2) I argue that cheaper launch can let spacecraft engineers spend mass instead of cash, bringing down the cost of Discovery and all other missions. Then we can have a solar system exploration program on the scale of the challenge.

Van: 08/30/2016 12:24 CDT

David - I presume that if either DaVinci or Lucy were selected as Discovery missions, then the similar New Frontiers missions would not be, but I don't believe that NASA's managers have said anything about this. Karen - A Venus flagship mission with an orbiter and balloons was a recommended low priority Flagship mission. Karl - Cassini will only sample the outermost fringes of Saturn's atmosphere where it is all but vacuum. The atmospheric probe would go to ~10 bars of pressure, much deeper. As for Uranus or Neptune, an atmospheric probe was included in the recommended Flagship class mission. Stephen - NASA is spending from now until late 2019 conducting the competition and analysis among the proposals from the science teams. The actual time to develop the mission is a pretty standard 4 years, 2020-2024. If plutonium is used, NASA believes it may need an extra year to prepare the RTGs. martinselvis - The paper you reference has interesting but still unproven ideas. NASA is exploring using a commercial satellite bus for its next Mars orbiter. The further you get from what commercial spacecraft were designed to do (generally orbit a terrestrial planet), the harder it would be to modify them for a mission.

DrMorbius: 08/30/2016 03:05 CDT

Was there any discussion of a low-cost Enceladus sample return mission? This would consists of one or more flights through a plume and then return to Earth.

Van: 08/30/2016 03:58 CDT

DrMorbius - Since there is a group that has been studying and promoting an Enceladus sample return as you describe, I strongly suspect that one will be proposed. The two challenges, as I understand it, are the very long flight times (to and from Saturn) and the cost of the sample containment and handling facilities. Since life might be returned, the samples have to be treated as a severe potential threat until proven otherwise.

DrMorbius: 08/30/2016 08:49 CDT

Interesting. Too bad that the sample cannot be returned to the ISS instead of Earth, but I suppose that de-acceleration requirements would be prohibitive. For Enceladus maybe it makes more sense to send a gas chromatograph / mass spectrometer to orbit the planet and do the analysis there.

ScienceNotFiction: 08/31/2016 05:03 CDT

What NASA need is to mass-produce a class of standard space probes loadable with standardized instruments and power modules.This probe should have options to carry a modifiable lander module that can be launched into the atmosphere/surface of the target system. This will cut down the costs of mission development while enabling more projects off the ground. We know the problem is that NASA does not want see too much technology leaks to the hands of foreign governments. International cooperation is always gonna be difficult. We really need an unified international space agency to conduct and to coordinate all sorts of space explorations. Member nations can help mass produce standard spacecrafts for standard exploratory missions.

Karen: 08/31/2016 12:52 CDT

Van: thanks for the response, that's incredibly encouraging! A Venus flagship - they could do so much with that budget! Do you have any information about this? Are they recommending a specific, already proposed mission (I've read through quite a few proposals) or seeking something altogether new? Martin: interesting paper, although obvious limitations come to mind. Cheaper, mass produced hardware is generally designed for terrestrial applications and is not necessarily suitable for space applications (for example, due to outgassing). In general, probes are generally made in such small volumes that you're going to have significant engineering costs no matter what. Plus, operations costs are often a very significant portion of a mission, and I can't see how reduction in costs would make them cheaper. But I can see arguments, for example, for more use of solar power instead of RTGs in marginal outer planets missions, that's an obvious potential savings. Very nice cite in reference #8, I'll have to hang onto that... unfortunate that it's so dated.

Tim: 08/31/2016 05:29 CDT

@Karl, I agree that the Uranian and Neptunian systems deserve dedicated orbiter missions of their own and there are plenty of other places that equally deserve study too like Pallas, Hygiea and Juno. I'd also like to see another mission to Venus to study the evolution of its crust and the internal structure of the planet using hardened seismometers. As ever, it's down to lack of money and resources and while that situation prevails, I'd like to see more cooperation and coordination between the Western space agencies of NASA, ESA and JAXA so that the maximum possible science gain is obtained from restricted budgets.

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