The Hard X-ray Modulated Telescope
is to be China's first dedicated astronomy satellite. It is also the first Chinese mission to be
selected through peer review.
In unveiling its five-year plan for
2006–10 this past March, the Chinese National Space Administration (CNSA) announced that
the HXMT had won a competition for funding, beating out a proposal for the Solar Space
Telescope (SST). A host of other astronomical projects are funded for various stages
of R&D.
Scheduled for launch in
2010, the HXMT will survey the sky in the 20–250 keV range. "In this energy
band, it should be the most sensitive instrument so far for a full-sky survey," says project coleader
Shuang Nan Zhang, who splits his time between Tsinghua University and the Institute of High Energy
Physics in Beijing. "It will take a year to scan the whole sky," he adds.
In addition to a hard x-ray
survey instrument, the mission will carry two lower-energy detectors—capable of observing
from 1 keV to 30 keV—for pointed observations. Possible targets for such observations
include neutron-star–black-hole binaries, active galactic nuclei, supernova remnants,
soft gamma-ray burst repeaters, and galaxy clusters. "With all the detectors pointed at the same
source," Zhang says, "we can look at sources with broadband spectra and rapid variability—like
a high-energy version of RXTE [NASA's Rossi X-ray Timing Explorer]."
China is providing the
launcher, spacecraft, and hard and medium x-ray detectors, while a low-energy detector will be
built jointly with scientists in the UK.
Unspecified budget
Zhang estimates the HXMT price
tag at about $100 million. "It's pretty cheap by international standards," he says. "But
in China it's a megaproject. It's the [country's] largest astronomy project ever." The country's
manned space program and lunar exploration plans—an orbiter will be launched this fall to
map the Moon's surface, followed by landers and rovers that will carry out experiments and bring
back samples—are larger, but they are not pure astronomy programs; the manned program is
not under the CNSA.
The total budget for space
science is unspecified, says Zhang, one of the architects of the CNSA five-year plan. "The government
does not give us a budget. There is no cap. We tell them our needs. We say, 'It's been approved, please
fund.' "
In the past, decisions
about space missions in China have been made at top government levels. This time, with peer review,
the people whose missions lost out were of course disappointed. But, says Zhang, the reaction from
the community about using peer review has been positive. "Everyone is a winner because we have established
the correct procedure."
Besides the HXMT, two projects
whose funding appears secure are the Long Slit Spectrograph, an instrument for the World Space
Observatory (see the story on page 32), and a microsatellite that will piggyback on a Russian
mission to Mars and gather information about the planet's atmosphere and magnetic field. For most
other proposed missions, says LSS project manager Maohai Huang of China's National Astronomical
Observatories in Beijing, "the status is in limbo. The fight for the actual level of funding for
all projects is far from over."
As for the SST,
the CNSA has now bundled evaluation of the telescope with another solar mission, Kua Fu—named
for a mythological figure who wanted to catch the Sun. The SST, which will have a 1-meter
telescope and five or more instruments, is intended to study solar flares and the Sun's magnetic
field. Kua Fu is a mission consisting of three satellites equipped to monitor space weather,
sample the solar wind, and study the Sun's corona and environment. The SST and Kua Fu
"have very different scientific missions," says Zhang. "We hope [the government] will fund both."
China has two space collaborations
in the works with France. Originally scheduled for launch in time for the next solar maximum in 2011,
the Small Explorer for Solar Eruptions is now expected to fly a year or so later. China is
responsible for one SMESE instrument, a spectrograph for detecting x rays and gamma rays.
The mission will also be able to image in the UV and IR. The main goal, says Cheng Fang, a solar physicist
at Nanjing University and a principal investigator for China's contribution to SMESE,
is to study solar flares and coronal mass eruptions. "China's contribution is roughly €5 million
[$6.7 million]. The French side is much more."
The other Franco–Sino
mission is a gamma-ray burst mission that is not listed in the CNSA's five-year plan, but which will
likely fly, according to a source who requested anonymity. It's scheduled for launch around 2012.
Further in the future,
perhaps around 2015, astronomers in China hope to launch the Solar Polar Orbit Radio Telescope,
an array of interferometric low-frequency antennas rotating around a mother spacecraft and together
forming a virtual dish about 150 meters in diameter. In solar polar orbit, SPORT would image
coronal mass ejection plasma clouds to study and forecast space weather.
International partners
In the current five-year plan, says
Zhang, China encourages international collaborations. "It means we should take every opportunity
to participate in good, scientifically motivated programs if we believe the science interests
match the interests of Chinese scientists. And it means the Chinese space program welcomes international
collaboration." Through such collaborations, Zhang adds, "We can be part of the international
community. That is what we want."
To date, China's collaborations
in space science are with Russia, the European Space Agency, and several European nations. The
Alpha Magnetic Spectrometer is an isolated case of a US–China collaboration—but
NASA has put it on hold (see PHYSICS TODAY, May 2007, page 30). Hopes in both countries' space science
communities that collaborations might be established grew at the prospect of NASA administrator
Michael Griffin's visit to China last year, but dimmed thanks to a narrowed itinerary and new US
sanctions on China's space industry, according to Gregory Kulacki, a China specialist at the Union
of Concerned Scientists.
The chill in space relations
was exacerbated after China shot down one of its own satellites in January (see PHYSICS TODAY, March
2007, pages 29 and 100). Scientific collaborations between the two countries are in any case complicated
by International Traffic in Arms Regulations, US laws that regulate the export and import of articles
and services considered to be potentially militarily sensitive.
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