Will Ares I ever get off the ground? Credit: NASA/MSFC

The presidential commission deliberating on NASA's future is closing in on seven possible scenarios that could shape US space operations for the coming decade. The options include running the International Space Station (ISS) for an extra five years, or even eschewing activities in low-Earth orbit and on the Moon in favour of a concerted push to send astronauts to Mars.

The 10-person panel, chaired by Norman Augustine, retired head of aerospace giant Lockheed Martin, laid out the options in a public meeting in Washington DC on 5 August.

It is impossible to guess which path President Obama will choose. The panel is still refining its analysis, and insists it is not making recommendations, merely offering choices (see 'Sending out an SOS'). But certain strategies feature far more prominently in the scenarios than others.

When science is an afterthought, it can be the first thing to go when budgets and schedules slip. Steven Squyres , Cornell University, New York

Five of the seven scenarios would extend the life of the ISS to 2020, past its currently scheduled destruction in 2015. Three of the seven could allow the space shuttle to live past 2011 (see 'Seven paths to space').

But only two spell out a future for Ares I, the rocket being built to replace the shuttle as the principal way of getting astronauts into space, even though some US$10 billion has been poured into designing and building the rocket and crew capsule. "They could have done it well," said panel member Bohdan Bejmuk, a retired Boeing executive who once managed the space shuttle. "But they don't have enough money."

The NASA budget called for by the Obama administration is billions of dollars less than former president George W. Bush had outlined in 2004 when he unveiled his 'Vision for Space Exploration' to the Moon and then Mars.

Three of the seven Augustine panel scenarios stick to Obama's reduced five-year budget outlook. The remaining four options allow for a slightly increased budget programme — with one casting aside all other short-term goals in order to send humans to Mars as quickly as possible.

The final number of options presented to the president may change between now and 31 August, when the panel will deliver their final report. The panel plans to cost out the scenarios by next week, and also to assess the benefits of each for 12 key areas.

Where's the science?

One of those areas is the potential to gain scientific knowledge from each strategy, says panel member and astrophysicist Christopher Chyba, of Princeton University in New Jersey.

To that end, yesterday's meeting was mostly devoted to presentations from scientists representing four communities supported by NASA: Earth sciences, space-borne biological and physical science, astrophysics and planetary science. Each presenter was connected in some way to the current or most recent decadal surveys, organized by the National Research Council, that each field uses to set research priorities. The panel asked each presenter to describe the usefulness of human spaceflight to their field.

Anthony Janetos, representing Earth sciences, was hard-pressed to find an example. The director of the Joint Global Change Research Institute in College Park, Maryland, Janetos hedged when panel member and former astronaut Leroy Chiao asked if the thousands of pictures he took during shuttle flights were really all that useful. Janetos said they were "marginally" useful. However, certain Earth-observing instruments are tested on the shuttle in pilot studies, he added.

Astronomer Marcia Rieke, of the University of Arizona in Tucson, said the obvious overlaps for human spaceflight and astronomy were the Hubble Space Telescope repair missions. Astronomers are also keen on having a heavy-lift launch rocket that can heft even bigger telescopes into space.

Elizabeth Cantwell, an associate director at Oak Ridge National Laboratory in Tennessee and co-chair of the decadal survey for biological and physical sciences in space, argued that there was a "great deal" of important work left to be done on the ISS.

The last of the science presentations came from planetary science decadal survey chair Steven Squyres, a geologist at Cornell University, New York, and project scientist for the Mars rovers Spirit and Opportunity, which have been exploring the red planet since early 2004.

He said that astronauts on Mars could do in a minute what his rovers averaged in a day, and pointed out that Spirit and Opportunity had covered less ground during their entire mission than Apollo astronauts in a lunar rover were able to travel in a day.

He added that humans could also add more value in complex environments such as Mars, compared with the Moon where many major science questions could be tackled by robots.

But he cautioned that science is rarely the primary goal of human spaceflight. "When science is an afterthought, it can be the first thing to go when budgets and schedules slip," he said. Squyres argued that the primary justification for human spaceflight lies in the inspiration it offers to the world – a view borne out by a recent Nature survey of scientists (see 'Shooting for the Moon').

But do those reasons justify an $80-billion programme over 10 years, asked Chyba. "To me that sounds like a darn good investment," said Squyres.