The Discovery program is unique in NASA’s planetary program. Within the budget constraints of each selection, the scientific community is free to propose any mission to any destination. In the last selection, the finalists were the InSight Mars geophysical station (which was selected), a mission to land on the lakes of Titan (TiME), and a mission to orbit and repeatedly land on the nucleus of a comet (CHopper). To paraphrase Forrest Gump, the Discovery program is like a box of chocolates – you never know what you’re going to get. The creativity of the scientific community has given us a wide assortment of missions in the past and is likely to surprise and delight us again.
The missions of the Discovery program have visited a wide-range of solar system destinations. These missions also have had a range of cost under- and overruns. Image from Historic Spacecraft and used under a creative commons license.
A month so or so ago, it appeared that the selection of NASA’s next mission in this, its lowest cost planetary mission program, was on indefinite hold. This program in its first decade produced an incredible wealth of data with ten missions that studied Mercury, the moon, Mars, asteroids, comets, and the sun. The program more than fulfilled its goal of ensuring that NASA’s planetary mission portfolio was diversified.
In the second decade, though, just two missions were approved, to the Moon and Mars. For the next decade it was uncertain when the next mission selection would begin. It appeared that already approved missions in development would consume most of the foreseeable mission development budget.
That has changed with the NASA budget that was just approved. Congress directed NASA to accelerate the selection of the next, thirteenth Discovery mission. Based on the proposals from the last Discovery mission (see list at the end), we can expect a good deal of creativity from the scientific community.
By contrast, the New Frontiers program ($750M to $1B missions) has a list of pre-selected, high priority missions (although creative solutions can be proposed). The other class of missions, Flagship missions ($1.5B+) like Cassini or Curiosity, are selected by panels of scientists and fostered and developed over a decade or two. The next two likely missions in this class, the 2020 Mars rover (already approved) and a Europa multi-flyby spacecraft (in study), are well known.
Realistically, there will be limits to the missions that can be proposed for the next Discovery mission. NASA’s managers will have to decide on the budget they can afford for the mission. In the past, scientists could propose missions with a total cost of ~$425M for the spacecraft, its operation, and the data analysis (NASA paid for the cost of the launch and some other expenses separately). Jim Green, head of NASA’s planetary program, said in a meeting recently that the budget will decide how ambitious missions could be. To afford a mission to the outer solar system, the budget would need to be closer to $500M, but a smaller budget could be set for missions to the moon, Venus, or Mars.
There also will be other key programmatic decisions. Will NASA pick up the costs of providing a plutonium power system to enable missions that can’t use solar panels for power such as spacecraft that would travel to Saturn, the permanently shadowed craters of the Moon, or land repeatedly on a comet? The latest count of available plutonium power systems suggests that one will be available for either a Discovery or a New Frontiers mission this decade.
A fixed budget also puts missions with long flights to their destinations at a disadvantage compared to missions that go to worlds next door. Each year of flight to reach a destination costs the mission $7M to $10M, a big disadvantage if the voyage takes five to seven years. The scientific community has proposed that NASA allow the budget to be flexible to cover costs of long flights.
Then there’s a question of how much risk NASA is willing to accept. The more ambitious the proposal, the greater the chance it would bust its development budget or fail sometime after launch. Commentators have said that NASA appears to have become risk adverse in its Discovery mission selections (see here). On the other hand, where NASA once had the budget to select two missions every two years, it now is looking at perhaps just two Discovery missions a decade. The relative cost of failure has grown, and low-risk, good-science missions have been available to select.
We will get answers to most of these questions in a few months when NASA releases the draft Announcement of Opportunity (AO) for the next selection. AO’s spell out what NASA is looking for, the budget it has set, the class of launch vehicles it will pay for, and what resources it will make available such as a plutonium power supply. Proposers will decide to propose or not in response to the constraints placed on the selection.
Congress asked that the AO be released this May, but NASA’s managers have said that they and the scientific community couldn’t be ready by that date. Instead, a draft AO will come out for the community to comment on in the next few months. NASA has said that the final AO will be released before next October.
Once the final AO is released, we will still need patience to wait to find out which mission is selected and even longer to see it reach its destination. The previous AO was released in June 2010, the three finalists were selected in May 2011, the winning InSight mission was selected in August 2012, and launch will come in 2016. If the next selection follows the same pace and the AO is released in, say, September 2014, the finalists may be known in August 2015, the winner selected in November 2016, and launch in 2020. If the mission goes to Venus, the moon, or Mars, it could arrive at its destination in weeks or months. If it goes to Saturn, it could take seven years.
There’s also a question of how NASA will fit this mission into its budget, which is already largely spoken for by missions in development.NASA had planned to release the AO for its next New Frontiers mission in 2015. Will that be delayed or does NASA think it can select two new missions this decade? We will know more when NASA’s proposed 2015 budget is released in March.
In the hopes that future budgets will support the selection and development of the next Discovery mission, this is the kick off post for what will be a semi-regular series of posts on missions that are likely to be proposed.
I’ll close with a list of previous Discovery mission selections and what’s known about the list of missions that were proposed for the last selection. This will give an idea of the range of creative missions that may be proposed for the next selection.
Selected DISCOVERY and Mars Scout missions
The Mars Scout program selected missions similar is scope to the Discovery program and has since been merged with the Discovery program. I’ve indicated these missions with an asterisk. The first two missions were selected by NASA without an AO.
NEAR – near Earth asteroid rendezvous and landing
Pathfinder – Mars lander and rover
AO Date and Missions
1994:Lunar Prospector - orbiter
1994: Stardust comet sample return and 2 comet flybys
1996: Genesis – returned samples of the solar wind
NASA does not release any information on missions proposed except for the three finalists (and then only limited information except for the winner). The competition is tough and most scientists propose multiple times, so most want to keep their proposals as confidential as possible. NASA did release the number of proposals for each class of destination. Where I can, I’ve listed additional detail based on what proposers stated publicly and based on a list maintained by Blackstar at the NASASpaceflight.com forum.