They carried astronauts into orbit and to the International Space Station.
They deployed satellites and repaired them.
They were orbiting space labs conducting countless scientific experiments.
But when NASA's Space Shuttle Atlantis touched down at Kennedy Space Center Florida
on July 21st, 2011 it marked the
ended the Space Shuttle era.
The shuttles Challenger, Columbia, Atlantis, Discovery,
Enterprise and Endeavor had been in service for 30 years.
Since 2011, American astronauts could no longer fly missions conducted from the Space Shuttle,
or transport astronauts or cargo to the International Space Station.
Since 2011, the
only way for astronauts to fly into space or travel to the International Space Station
was aboard the Russian space craft Soyuz.
But all that is out about to change.
NASA, in partnership with Sierra Nevada Corporation
is developing the next generation Space Shuttle called Dream Chaser.
The idea for Dream Chaser began in June 1982
when an Australian P-3 patrol plane took
images have a Soviet ship recovering a spacecraft from the Indian Ocean.
Employees at NASA's Langley Research Center used that model and started
building its own horizontal landing craft called HL-20.
The original HL-20 was designed as a compliment to the Space Shuttle.
It could transport people and small amounts of cargo
and act as a rescue vehicle if needed. It could be used to service satellites or for
observation missions.
The idea of a space taxi stalled however
and the HL- 20 project was cancelled.
NASA moved on to other pursuits.
The craft was warehouse where it remained collecting dust for 20 years.
Years later with renewed interest in developing an alternative to the Space Shuttle,
Sierra Nevada Corporation was looking for an idea for a space taxi system
and look to the HL-20 as a viable answer.
The HL-20's history of being the most extensively tested and reviewed vehicle
was a good choice to build upon.
By 2004 Dream Chaser was being redeveloped and prepared as a candidate
for NASA's Commercial Orbital Transportation Services program or COTS.
By August 2012 after extensive testing and redevelopment the Sierra
Nevada Corporation was awarded $212.5 million dollars
to continue work on the Dream Chaser.
Dream Chaser is a reusable transportation spacecraft designed to
carry from two to seven people
and/or cargo to orbital destinations
such as the International Space Station where can remain docked for 210 days.
It has the capability of delivering crew and cargo to
other orbiting destinations as well or function as a short term
independent orbiting laboratory for government agencies
or commercial entities as well as potential
orbital space tourism. It has a built in launch escape system
and can fly by itself if needed. The vehicle is able to return from space by
gliding and landing on
any airport runway that handles commercial air traffic.
Astronauts will experience less than 1.5 g upon re-entry
as compared to the space shuttle's 3g. Its reaction control system thrusters
burn ethanol based fuel which is not an explosively volatile material
allowing the craft be handled immediately after landing
unlike the Space Shuttle.
Dream Chaser is smaller than the original Space Shuttle. The Space Shuttle stood 121.5 feet tall
and 78 feet wide whereas the Dream Chaser stands 29.5 feet tall
and 23.5 feet wide. It is a fraction of the size of the Space Shuttle
and could with its wings folded fit inside the cargo bay of the Shuttle.
Unlike solid rockets
Dream Chaser's hybrid fuel system allows the motor to stop and start repeatedly
and be throttleable.
On orbit propulsion is a hybrid system fueled with hydroxyl terminated polybutadiene
HTPB and nitrous oxide
or as some call it rubber and laughing gas.
These elements are non-toxic and easy to store
and are safer than liquid rocket fuels.
Its heat shield tiles can be replaced as a large group rather than tile by tile.
Dream Chaser can use any suitable launch vehicle
but is slated to be launched atop an Atlas V 402 rocket.
SNC is one of three companies funded under NASA's CCiCAP Initiative
to develop a next generation crew transportation vehicle.
Other concepts are also being developed,
including Boeing's Bigelow crew space transportation system,
Space X's Dragon
Orbital Sciences Cygnus Cargo Spacecraft,
and NASA's Orion Spacecraft.
But Sierra Nevada Corporation's Dream Chaser
remains the only non-capsule reusable lifting body vehicle with
runway landing capability. Several successful development milestones have
been met by Dream Chaser
during 2010, 11, 12, and 2013.
On January 30, 2013
SNC announced a new partnership with Lockheed Martin.
Lockheed Martin will develop a second airframe
and is slated to be the first orbital test vehicle.
Full orbital flights are scheduled for 2017
and will usher in a new Space Shuttle Era.