As the space shuttle Discovery prepares for launch, another Nasa spacecraft sits in storage, awaiting its own ride into space.
DSCOVR is currently grounded
The Deep Space Climate Observatory (DSCOVR), designed to measure the Earth's solar energy balance and which has already been built, is grounded at Nasa's Goddard Space Flight Center in Maryland, after the agency cancelled it, citing competing priorities.
The $100m (£50m) science platform is paid for, apart from the funds needed for the launch and ensuing research.
"It is, as Nasa says, 'in mothballs,'" said DSCOVR lead scientist Francisco Valero of the Scripps Institution of Oceanography at University of California, San Diego.
The instrument was to orbit the Sun at the Lagrange point, where the combined - and oppositely directed - gravitational forces of the Sun and the Earth yield an orbital period the same as Earth's.
This would allow the satellite to hold its position and provide the first direct, continuous measurements of solar radiation and absorption.
"You are looking at the fully illuminated Earth all the time," said Dr Valero, "so you can continuously measure changes in the amount of reflected energy."
Dr Valero continues to advocate for DSCOVR's launch, although there has been no move by Nasa to reinstate it.
The climate satellite is one of a number, designed to provide critical information on the Earth's climate, which have been delayed or cancelled since Nasa trimmed its science mission budget.
Four hundred million dollars (£200m) have been cut to pay for shuttle flights to the International Space Station and to return astronauts to the Moon.
Instruments on other cancelled satellites were to provide more accurate measurements in global precipitation, aerosol size and distribution, ocean winds and atmospheric temperature.
They would help to fill in missing climate data at a time when the Earth is warming and discussion about how to respond to climate change is ongoing.
Charles Kennel, the director of Scripps Institution of Oceanography and former head of Nasa's Mission to Planet Earth programme says the cancellations and delays will lead to serious gaps in climate data.
"Closing those gaps would create a level of certainty that is far less challengeable," said Dr Kennel.
"The danger is that an already cloudy debate will become more cloudy for lack of data."
While the shuttle launch is a reminder of Nasa's role in space, the agency also has a key goal to study Earth.
But Nasa's dedication to Earth observation has diminished over the last decade, according to Dr Kennel, culminating in the recent budget reshuffling, which he says reflects an "over-commitment" to the president's vision of space exploration.
He says the climate satellites are important individually, but more so for the coherent and integrated picture of the Earth's climate they provide together. And the view from space is a necessary complement to ground-based monitoring.
"You can't have one without the other," said Dr Kennel. "Space provides the only view of the whole Earth from above."
The cancelled Ocean Vector Winds (OVW) mission was to monitor ocean wind speed and direction and to provide continuity with QuikScat, a satellite now working beyond its nominal mission.
Surface winds are important because they drive the oceans, creating atmospheric drag that produces surface waves and large-scale current systems such as the Gulf Stream, and stirs the general circulation of the upper ocean.
"Climate is essentially a coupling of the Earth's two great fluid systems: the ocean and the atmosphere," said Michael Freilich, an oceanographer at Oregon State University and the science team leader on OVW. "And winds change the geometry of the surface of the ocean."
Monitoring sea surface winds also leads to early detection of closed circulation systems that become hurricanes, and may help determine the patterns that influence, or even trigger, the El Nino Southern Oscillation.
It is also key to weather forecasting. Without OVW to replace QuikScat, important weather data will be lost.
Some of the missions measuring precipitation have been delayed
"From a weather forecasting standpoint, it's devastating," said Dr Freilich, who says the wind measurements guide marine warnings as well as prediction of large-scale weather events.
"Without the data, we'll be turning the clocks back many, many years in terms of our skill," he said.
The Global Precipitation Measurement (GPM), a joint project with Japan to measure the fall of snow, rain and ice, has been delayed by two and a half years to 2013, although there is effort within Nasa now to accelerate the launch date.
The delay might jeopardize the partnership with the Japanese, who have not formally agreed to the new launch schedule, said Arthur Hou, GPM project scientist at Nasa's Goddard Space Flight Center.
The delay also interferes with data continuity. GPM is to pick up where the Tropical Rainfall Measuring Mission (TRMM), due to expire in 2012, leaves off, to provide a continuous measurement of global precipitation and to fill in the data gaps of TRMM.
While TRMM has provided good measurements of precipitation at the tropics, coverage of mid-to-high latitude areas was patchy, said Dr Hou.
Currently, he said, no satellite was measuring snowfall or light rain, which in the mid-to-high latitudes can account for 50% of the precipitation.
Dr Hou said GPM would help eliminate the uncertainties in the Earth's water budget and answer questions such as how precipitation might change as the climate warms.
"We don't have a reliable answer to that right now," said Dr Hou, "and we need good measurements to get one.
"Water is fundamental to everything on Earth, it dominates the workings of the Earth's weather and climate," he said. "It's at the heart of the Earth system."
As Nasa's Earth sciences have been scaled back, so too have space sciences. The agency has cancelled or deferred a number of projects designed to examine dark energy, hunt for extra-solar planets, investigate the origins of the Universe and measure gravitational waves to test Einstein's general theory of relativity.
But some investigators have re-directed their energies.
The cancelled Nuclear Spectroscopic Telescope Array, (NuStar), a low-cost mission ($134 m, £73m) in the Small Explorer Program, was to take the first focused high-energy X-ray pictures of black holes and newly exploding stars.
"When stars explode, they distribute elements though galaxies so that they can aggregate and form planets and life. Essentially, our bodies are all star-stuff," said Fiona Harrison, California Institute of Technology astrophysicist and principal investigator of NuStar.
"We'd like to know how stars explode and distribute these elements throughout the galaxy," she said.
After NuStar's cancellation, Dr Harrison re-focused her efforts when another source of funding appeared.
Her team now is modifying the radiation detectors that would have peered into black holes for use in monitoring the transport of clandestine nuclear materials, for Homeland Security, which stepped in after Nasa pulled out.
"It's not where my heart is or why I got a PhD in astrophysics," said Dr Harrison. "I hope this is a temporary diversion and that Nasa's science programme will once again become vigorous and healthy."