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 Forest 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. 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 missions of 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 (except the tolerance
for risk) 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.
SpaceNews
also has an article on the selection of the next Discovery mission.
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
1996: CONTOUR – multiple comet
flybys (failed)
1998: Deep Impact – Delivered impactor
to comet & 2 comet flybys
1998: MESSENGER – Mercury orbiter
2000: Kepler – exoplanet hunter
2000: Dawn – orbit asteroids
Vesta and Ceres
2002: *Phoenix – Mars polar
lander
2006: GRAIL – 2 lunar orbiters
2006: *MAVEN – Mars orbiter
2010: InSight – Mars geophysical
station
Proposals in response to the 2010 AO
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.
Venus – 7 proposals
4 proposals reportedly for radar
mapping missions
At least one for an atmospheric probe
Moon – 3 proposals
Moon – 3 proposals
Lunar seismic station
Lunar south pole ice prospector(s)
Mars and it's moons – 4 proposals
Mars and it's moons – 4 proposals
Mars geophysical station (InSight)
Asteroids – 8 proposals
Asteroids – 8 proposals
A near Earth asteroid lander
Near Earth asteroid survey
Jupiter system – 1 proposals
Jupiter system – 1 proposals
Io multi-flyby
Saturn system – 2 proposals
Saturn system – 2 proposals
Titan lake lander (TiME)
Titan and Enceladus multi-flyby (JET)
Comets – 3 proposals
Comets – 3 proposals
Comet Hopper (CHOPPER)
Van, todays announcement of US French agreement on InSight, can you tell if this means budget freed up to possibly save Cassini? Or not related?
ReplyDeleteAnon -
ReplyDeleteThis agreement was a bureaucratic non-event. The InSight seismometer will be supplied by a French research team and their work is funded by the French government. When there is a foreign instrument, there is this kind of agreement. If it hasn't already happened, then there will be a similar agreement for the German-supplied heat flow instrument.
The only US-supplied InSight instrument will be the ultra-precise radio distancing experiment to detect minute changes in Mars wobble as it spins on its axis.
To save money, its common for US teams to propose flying foreign instruments and the result can be that the majority of instruments are non-US. Sometimes a US team could have supplied an equivalent instrument. In other cases, foreign research teams have the best instruments available, and it's my understanding that this was the case for InSight. Saving money was a nice extra benefit.