Earth
Mars- Spacecraft
“Here I am.” - Atomic clock
Receives signal, makes calculations
and sends back data to spacecraft. - Engineer
“What is
your position?”
Deep Space Atomic ClockATOMIC^ CLOCK- Spacecraft
“Approaching
destination: Mars!” - Engineer
“Where are you?”
14 ASTRONOMY • JANUARY 2020
X-RAY
FLASHES
REVEAL A
POSSIBLE
BLACK HOLE
The Fireworks Galaxy
(NGC 6946) is named
for the large number of
supernovae popping off
within it. This image com-
bines a visible-light shot
of the galaxy from the
Sloan Digital Sky Survey
with X-rays, colored blue
and green, observed by
NASA’s NuSTAR space
observatory. The circular
blue-green spots above
the galaxy’s center are
two such supernovae,
which signal the deaths of
massive stars. Researchers
believe the large green
blob of X-rays below the
galaxy’s center, which
appeared over the
course of 10 days,
could be from a black
hole devouring a
star. Alternatively, an
outburst from a rapidly
spinning neutron star,
the tiny remnant of a
once-massive star, could
be to blame for the sudden
f lare of X-rays. — A.K.MEET THE DEEP SPACE ATOMIC CLOCK
NAVIGATING IN SPACE IS ABOUT TO GET EASIER.
Spacecraft today use a two-way system to determine
their speed and position in space. Engineers on Earth send a signal to the spacecraft,
then wait for the craft to receive it and send a signal back to measure where the mission
is located and how fast it’s going. But that system gets slower with increasing distance
from Earth, because it takes time for the signal to reach its destination and return.QUANTUM GRAVITY
CURRENTLY, atomic clocks are typically
too large and power-hungry to easily
carry on spacecraft. But in late June, NASA
launched its Deep Space Atomic Clock,
a proof-of-concept atomic clock that
measures the regular vibrations of charged
mercury atoms, or ions, to keep time in space. The 35-pound (16 kilograms), toaster oven-sized
clock will function in Earth orbit for a year to demonstrate whether such small atomic clocks
could be sent on future crewed and uncrewed missions to the Moon, Mars, and beyond.IN THE FUTURE, if spacecraft have their own
atomic clocks on board, it would cut in half the
time it takes to determine position and speed. A
craft with its own atomic clock could determine
this information based on the signal it receives
from Earth without the need to send one back. — A.K.NA
SA/JPL- CA
LTECHBased on lab tests, the Deep Space Atomic Clock
is so accurate it loses only 1 second every 10 million years.
That’s 50 times more accurate than the current GPS satellites’ clocks.FAST FACTASTRO
NOMY
:^ ROEN^KELLY