September–October 2015 27I
T’S UP THER E. Again. The US Air
Force’s ultra-secret X-37B robotic
space shuttle was launched into orbit
from Cape Canaveral on 20 May, for a
mission anticipated to last about nine
months. We have been told about this
and previous missions that the purpose
is the testing of reusable technologies,
such as thermal protection for space-
craft. But space buffs are sceptical.
Although everyone is intrigued by
military secrets, it’s frustrating to be
scratching around for crumbs of infor-
mation about what is arguably one of
the most exciting projects in contempo-
rary space flight. We can understand the
need for secrecy when national security
is at stake, but we can also hope that one
day soon, this advanced know-how will
find its way into civilian astronautics.
So what do we know about the reusa-
ble space plane? First, it bears a striking
resemblance to the crewed space shut-
tles that NASA flew into orbit from
1981 to 2011. At 8.9m long, it’s only a
quarter the size, however. And it’s fully
robotic. Launched vertically atop an
Atlas V rocket, it lands on a runway, just
as the piloted shuttle did. This is thecraft’s fourth mission – the last one
ended with a touch-down in California,
in October 2014, after 674 days in orbit.
Its heritage is also interesting. The
X-37B started life as the X-37 project, a
NASA venture that began in the late
1990s with the aim of exploring the pos-
sibility of shifting a spacecraft’s orbit in
flight. Rendezvousing with ailing satel-
lites to perform repairs was one goal. In
2004, however, the project was aban-
doned by NASA, and transferred to the
Defense Advanced Research Projects
Agency (DA R PA) – whereupon it was
declared classified. And that was that.
An entirely predictable consequence
of all this secrecy is the plethora of con-
spiracy theories that has surrounded the
X-37B – these include that it is a device
for dropping bombs from space or that
the plan is to use it to capture and inter-
fere with foreign satellites. Suffice it to
say that the Pentagon has categorically
denied that it is used as a test-bed for
space weapons. The rest is just specula-
tion. One day, perhaps, we will find out.FRED WATSON is astronomer-in-charge
of the Australian Astronomical Observatory.Why introduce a leap second
every 18 months to compen-
sate for the slow-down of
Earth’s rotation, when the
accumulated effect should only
amount to 7 milliseconds?
Wayne Robinson, Kingsley, WAYou’re quite right that the drift of
astronomical time away from
atomic clock time is only partially
due to the gradual slow-down in
Earth’s rotation. Other contributors
include irregular natural phenom-
ena such as the redistribution of
magma in the Earth’s mantle.If you have a space question for Fred,
email it to [email protected]Fred answers
your questions
x1
NAKED EYE Venus has
become the morning star.
Mars, followed by Jupiter, chases
this ‘Goddess of Love’ as it rises out
of the dawn. Jupiter passes Mars on
18 October, catching Venus on the
26th, when these beacons will be
only two moon widths apart!BINOCULARS The
random group of faint
stars making up the constellation of
Aquarius, the Water Bearer, looks
nothing like a kneeling man, but his
water jar is a distinctive group of
four stars arranged in a ‘Y’ shape.SMALL TELESCOPE The
obscure constellation of
Pavo is home to two spectacular
deep-sky objects. The face-on spiral
galaxy NGC 6744 displays a
prominent central bar, while the
globular star cluster NGC 6752
has a bright centre.Glenn Dawes is a co-author
of Astronomy 2015 Australia
(Quasar Publishing).Glenn Dawes
looking up
x10x1x10 0Mystery mission. Little is
known about the latest
space flight of the X-37B,
which launched in May.From orbit
with love
The US defence agency’s ‘secret’ space
shuttle is up to something once again.
SPACE
EPA/BOEING / SALLY ARISTEI