The Space Shuttle Orbiter is an iconic symbol
of human space exploration, and we haven’t
seen anything like its unique design since
its retirement in 2011.
But now, at Sierra Nevada Corporation’s
facility in Colorado, engineers are in the
beginning stages of assembling the new space
plane, fondly known as Dream Chaser.
This vehicle is actually one of NASA’s Commercial
Resupply Services 2 contract recipients, and
it will join the fleet of utility spacecraft
like SpaceX’s Dragon capsule and Northrop
Grumman's Cygnus module—both of which hold
the important task of transporting cargo to
the International Space Station.
But there’s one key difference, and it's
that Dream Chaser is shaped like a plane,
and SNC aims to land it back to Earth just
like one, too.
This design allows for the space plane to
be reused 15 times or more, which reduces
costs and allows for quick turnaround between
missions.
But what makes the Dream Chaser so enticing
is that it's capable of supporting a variety
of needs.
It can land on runways used for passenger
planes, carry various loads of cargo, support
a microgravity lab, and dispose of waste from
the ISS.
Now, the distinction starts within its aerodynamic
structure.
Dream Chaser is a “lifting-body” spacecraft.
In typical aircraft, the wings are what help
create lift and keep the plane airborne.
But with Dream Chaser, the lift is created
from air pressure on the underside of its
body, which is wide, flat, and equipped with
heat-resistant silica-based tiles and a new
material called ‘TUFROC’.
So when Dream Chaser returns to Earth from,
for example, a re-supply mission, the resistance
of its fall will help the craft come down
with a steady glide, no extra power needed.
Lifting-body spacecraft have less gravitational
forces working against the plane during reentry,
we’re talking a max of 1.5 gs (which is
less than most roller coasters), so landing
is now easier on sensitive scientific experiments
on board.
Plus, gliding allows for touchdown to be on
a runway, rather than crashing into the ocean.
The plane also uses a nontoxic propellant
which let’s it land anywhere in the world
a Boeing 737 airliner can.
Dream Chaser will be utilizing SNC’s upper-stage
Vortex engine, which is low cost and uses
less toxic fuels that can ignite at high altitudes.
AND since the chemicals involved are non-toxic,
there can be an immediate turnaround once
it lands.
In comparison, for older space shuttle orbiters
that used hydrazine, it would take around
30 minutes before people could approach the
vehicle and even then, they wore suits.
Other noteworthy parts of this spacecraft
are its ability to hold up to 5,500 kilograms
of pressurized and unpressurized essential
cargo like food, water, and science experiments,
which will be the largest of any cargo carrier.
Compared to Dragon cargo missions that have
been averaging around 1,500 kilograms of pressurized
cargo, and Cygnus with a highest load of 3,700
kilograms, the Dream Chaser is a bit of a
powerhouse.
It can get this big because it has a seperate
cargo module that is specifically designed
to be filled with about 3,400 kilograms of
waste from the ISS.
This garbage module will be released during
descent and burn up into the atmosphere.
On Dream Chaser itself, it’s set to return
up to 1,800 kilograms of work.
Some of which could be scientific experiments
JUST conducted on the descent itself.
See, the Dream Chaser can also be an intermittent
space lab either docked onto the ISS, or while
it’s experiencing microgravity on its way
down to Earth.
Experiments that don’t need long-duration
space exposure could take advantage of this,
and gather their data immediately rather than
wait months before another cargo mission brought
their equipment down.
So now, you might be asking yourself, if this
space plane hits all the key points, why has
it taken so long to get here?
Well, the Dream Chaser team has had a long
journey.
The design concept for this space plane was
resurrected from past lifting-body planes,
but it really took off when NASA asked private
companies to create ‘space taxis’ to ferry
astronauts to and from the ISS.
So, SNC actually created Dream Chaser to be
a crewed vehicle, but in 2014, NASA selected
SpaceX and Boeing with commercial crew contracts
But SNC took the Dream Chaser, and redesigned
it to be the cargo vehicle we are excited
for today, and was able to nab a cargo contract
with NASA to fly six missions to the ISS through
2024.
Now in 2019, Dream Chaser continues to pass
milestones and the version that will take
to the skies is being assembled as we speak.
When it’s ready for take-off, the plane
will sit atop ULA’s new launcher, the Vulcan
Centaur rocket with plans to begin ferrying
cargo in 2021.
This next-generation space plane may very
well be the new icon of human spaceflight
for years to come.
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