ISS Temporarily Down to Crew of 2

Following today’s departure of the three man crew of Expedition 21 aboard the Soyuz TMA 15 capsule, staffing on the International Space Station (ISS) is now temporarily reduced to a skeleton crew of just 2 men for the first time since July 2006. The ISS had hosted a complete 6 person and truly international crew complement for the first time ever since its inception, starting in May of this year.

Soyuz Commander Roman Romanenko (Russia), European Space Agency Flight Engineer Frank De Winne (Belgium) and Canadian Space Agency Flight Engineer Bob Thirsk floated into their three segment Soyuz return capsule on Monday evening, Nov 30. After powering up systems and a farewell ceremony the hatches were closed at 7:43 PM EST. They disengaged hooks and latches and then physically undocked from the Zarya module at 10:56 PM over Mongolia after spending 188 days in space. De Winne was the first European commander of the ISS. All prior commanders have been either Russian or American. Romanenko is a second generation cosmonaut. His father Yuri, flew his first mission in 1980. Thirsk is the first long duration Canadian astronaut.

Soyuz TMA 15 landing track. Credit: NASA TV
Soyuz TMA 15 landing track. Credit: NASA TV

Retro rockets were fired for 4 min 19 sec at 1:26 AM Tuesday morning to initiate the de-orbit braking maneuver for the fiery plunge of atmospheric reentry. 19 minutes later the three Soyuz segments pyrotechnically separated at an altitude of 87 miles. The Soyuz barreled backwards as it hit the earth’s atmosphere at 400,000 ft above Africa and the crew experienced maximum G forces. The three parachuted to a safe touchdown strapped inside their Soyuz descent module onto the snowy steppes of Kazakhstan at 2:15 AM Tuesday Dec 1 (1:15 PM Kazakhstan local time) thereby concluding a mission that began with a May 27 blast off. Russian search and recovery forces drove to the ice cold landing zone at Arkalyk to greet and assist the trio in opening the hatch, exiting the craft, readapting to earth’s gravity and returning to Star City. This was the first December landing of a Soyuz since 1990.

Poor icy weather and low clouds grounded the normal recovery force of 8 helicopters. The capsule landed right on target and in an upright configuration. Recovery forces sped quickly into place. Romanenko was first to depart out the top hatch of the capsule, followed by Thirsk and De Winne. They were carefully extracted by the ground based recovery team and immediately assisted into stretchers while smiling broadly and waving to the crowd. Then they were swiftly slid into all terrain vehicles larger than their capsule for the initial leg of the ride back to Russia. Flight surgeons confirmed the health of the crew who are eager to re-unite with family and friends and earthly comforts.

The Expedition 22 core crew of NASA Commander Jeff Williams and Russian Flight Engineer Max Suraev remain as the sole two occupants for about three weeks until the Dec 23 arrival of the next international crew comprising Russian cosmonaut Oleg Kotov, NASA’s T.J. Creamer, and Soichi Noguchi of the Japan Aerospace Exploration Agency who head to the station Dec. 20 on the Soyuz TMA-17 craft from the Baikonur Cosmodrome. Williams and Suraev arrived by Soyuz capsule TMA -16 in October.

US astronaut Nicolle Stott rounded out the six person ISS crew until her departure just days ago on Nov 25 aboard shuttle Atlantis (link) left just five people on board. She spent 91 days aloft conducting science experiments and has the distinction of being the last ISS resident to hitch a ride up and down on a shuttle. Future crew rotations are planned via Russian Soyuz rockets since the shuttle will be retired by late 2010 and NASA’s Ares / Orion launch system won’t debut until 2015 or later.

Watch video of the shuttle “belly flip” as it arrives at the station.

During 7 days of joint operations in late November, the ISS boasted an ethnically diverse population of 12 humans from the combined crews of STS 129 Atlantis and the resident ISS members from two docked Soyuz capsules, just shy of the record 13 occupants. With all the comings and goings of assorted manned and robotic spaceships lately it’s been an exceptionally busy time that required careful planning and traffic coordination among the world’s space agencies.

The 800,000 pound station is now 86% complete and thus far larger and more complex compared to the last instance of a two person contingent. Since the 2005 Return to Flight of the shuttle following the Columbia accident, several habitable modules (Harmony, Columbus, Kibo, Poisk), truss segments, radiators, stowage platforms and giant solar arrays have been attached. All this has vastly expanded the astronauts and cosmonauts daily responsibilities of both maintaining station systems and carrying out a much expanded scientific research program.

Bill Gerstenmaier, NASA’s chief of space operations, said the ISS partners have carefully looked at the operational challenges of this three week interlude to make sure “there is not a lot of activity going on then, other than some software uploads. We moved all the major activities that were occurring to other periods when there will be more crew. We are prepared and ready to cut back a little on operations but still be able to do a little bit of science research with just two crew members on orbit.”

Three space walks by the Atlantis crew helped pave the way for the next shuttle ISS assembly flight in February 2010, designated STS 130, which will haul up the long awaited Tranquility and Cupola modules and which I recently observed close up at the ESA to NASA hand off ceremony inside the Space Station Processing Facility (link) (SSPF) at the Kennedy Space Center.

Atlantis delivered two large pallets loaded with 15 tons of critical spare parts that will help extend the working lifetime of the ISS and serve as a hedge against on orbit equipment failures ahead of the fast approaching deadline when the space shuttle is no longer available to loft such bulky gear.

Only 5 flights remain until the shuttle era ends late in 2010. The Orion capsule will not debut for at least five years and perhaps longer, dependent on funding decisions in Washington, DC. The station will then be completely dependent for supplies and equipment on Russian, European and Japanese cargo vehicles. Test flights of US commercial ISS transport vessels begin next year.

Not until another three person Soyuz blasts off next April 2010, will the station return to a full team of six. But science research will be full speed ahead.

Amazing Images from STS-129

If I didn’t know better, I’d swear some of the images from the STS-129 shuttle mission to the International Space Station were CGI renderings taken from a science fiction novel. Take the above image, for example of astronaut Mike Foreman working on the exterior of the ISS during the second space walk of the mission. It looks almost surreal. But these are genuine images of real people working on an authentic, almost-completed space station. This images, and the other images below, leave me in awe of what we are accomplishing in space. Enjoy this gallery of amazing images from the fifth and last shuttle flight of 2009.

Robert Satcher on the Canadarm2 during the first space walk of STS-129. Credit: NASA
Robert Satcher on the Canadarm2 during the first space walk of STS-129. Credit: NASA

Here’s another awe-inspiring image. Anchored to a Canadarm2 mobile foot restraint, astronaut Robert Satcher Jr. works during the first space walk of the mission. Satcher and Mike Foreman (out of frame)installed antennas, cables, and other items to prepare for the Tranquility node that will be brought up to the station next year.

Starship Enterprise?  No, just the space shuttle and space station. Credit: NASA
Starship Enterprise? No, just the space shuttle and space station. Credit: NASA

There was some chatter on Twitter that this image brought to mind visions of the Starship Enterprise from Star Trek. But this is a closeup of Atlantis’ docking ring backdropped by the ISS as the shuttle crew approached for docking with the station. Docking occurred at 10:51 a.m. (CST) on Nov. 18, 2009.

Sun rise in space. Credit: NASA

Another great shot: Sunrise in space. This scene shows from the Russian section of the ISS, as photographed by one of the STS-129 crew members.

Satcher works on the Z1 truss.  Credit: NASA
Satcher works on the Z1 truss. Credit: NASA

I always love these images which demonstrate how HUGE the ISS is. Here, Robert Satcher works on the Z1 truss section during the first EVA of the mission.

ISS and docked spacecraft. Credit: NASA
ISS and docked spacecraft. Credit: NASA

Taking on the appearance of a busy spaceport, the Russian segment of the ISS has a docked Soyuz spacecraft (center) and a Progress resupply vehicle that is docked to the Pirs Docking Compartment.

Mike Foreman looks at his spacewalking partner Randy Bresnik.  Credit: NASA
Mike Foreman looks at his spacewalking partner Randy Bresnik. Credit: NASA

Every shuttle mission picture gallery isn’t complete without a picture of an astronaut with another astronaut visible in the helmet visor reflection. Here, Mike Foreman’s helmet reveals his crewmate, Randy Bresnik, capturing the image with an electronic still camera. The two were in the midst of the second scheduled space walk for the Atlantis crewmembers.

Upside down, or not?  Credit: NASA
Upside down, or not? Credit: NASA

Who is upside down? Charlie Hobaugh (left), STS-129 commander and Robert Satcher , or the astronaut who took the picture? The two are pictured near a window in the Destiny laboratory.

Mealtime on the ISS. Credit: NASA
Mealtime on the ISS. Credit: NASA

Eight of the 12 crew members of the joint ISS/shuttle crews pose for a photo at the galley in the Unity node. Pictured from the left are NASA astronauts Leland Melvin, Robert Satcher Jr., Charlie Hobaugh, Nicole Stott, cosmonauts Roman Romanenko, Maxim Suraev, and astronauts Jeff Williams, and Frank De Winne, commander of Expedition 21 from the ESA.

Launch of Atlantis on Nov. 16, 2009. Credit: NASA
Launch of Atlantis on Nov. 16, 2009. Credit: NASA

A gorgeous shot of Atlantis’ launch on Nov. 16. Below is another launch picture, with the members of the NASA Tweetup watching by the famous countdown clock.

Atlantis' launch with Twitterers.  Photo credit:Jim Grossmann
Atlantis' launch with Twitterers. Photo credit:Jim Grossmann

Romanian Group Attempts Moon Mission With Giant Balloon

The first attempt to send a rocket to the Moon via balloon hit a snag on Monday. The first test of the Aeronautics and Cosmonautics Romanian Association’s (ARCA) balloon-launched rocket (or “rockoon”) ended in failure when the “inflation arms” used to fill the balloon became entangled in the balloon itself. The arms had to be cut, and the operation – which required the use of a large naval frigate — was curtailed. ARCA hopes to compete in the Google Lunar X PRIZE, and intends on using their unusual rocket system to send an equally unique spherical lunar lander to win a $30 million prize.

Rockoons were tried and then abandoned by the US in the 1950s because they blew off course in windy conditions.

ARCA’s European Lunar Explorer (ELE) is a simple design. The super-huge balloon carrying a system of three rockets will soar to about 11 miles (18 km) up. Then the first two rocket stages will fire and boost the system into low Earth orbit, and use the final stage to boost it to the Moon. The ELE will then travel to the moon and deploy its Lunar Lander, which resembles a knobby rubber ball that uses its own rocket engine to ensure a soft landing. Watch their video of how it all will work below: (If nothing else, watch it for the great music!)

On Monday, the Romanians loaded their prototype moon-balloon rocket onto the a large Romanian naval frigate, the Constanta, which took the entire crew out to the launch site in the Black Sea.

But as the balloon started to inflate, the inflation mechanism arms got tangled, and the entire operation had to be abandoned. The giant black balloon collects heat from the sun instead of using burners like hot-air balloons normally use, so it needs to launch during the day.

The Google Lunar X PRIZE challenges participants to construct a delivery system that will get a rover to the Moon, where the robot has to drive for about 500 meters, take high-resolution pictures of its surroundings, and then send them back home.

Undoubtedly, the ARCA team will try again.

See the images from Monday’s launch attempt.

Google Lunar X PRIZE

Source: Nature Blog

Atlantis Roars to Space for Trek to ISS

(Editor’s Note: Ken Kremer is in Florida for Universe Today covering the launch of Atlantis.)
Space Shuttle Atlantis and her six person crew roared into space on Monday precisely as planned at 2:28 PM EST from the Kennedy Space Center in Florida. The yellow exhaust flames grew into a nearly blinding intensity as Atlantis ascended off the pad on a trail of crackling fire and smoke. For what felt like an eternity, it seemed like Atlantis would be engulfed in a rapidly expanding inferno emanating from her tail in mid air. The time span was in reality perhaps 5 seconds. Atlantis then dove straight upwards, arced over and finally looked like she would return back to Kennedy on a big circular loop directly through the wake of the exhaust plume. In fact that sight was just an optical illusion but the feeling was shared by other media I conversed with here at the KSC Press site.

As Atlantis rose on 7 million pounds of liftoff thrust following ignition of the 3 space shuttle main engines and twin solid rocket boosters we saw her rotate about her vertical axis. Atlantis swiftly rising exhaust trail was clearly visible for about three minutes as she ascended northwards up the east coast of the United States for her trek into the orbital plane of the International Space Station (ISS) and carefully choreographed link up in 2 days time.

Gloomy early morning skies which were completely overcast had threatened to delay the launch. At a post-launch briefing, even senior Shuttle manager Mike Moses related how he awoke to the unexpected turn in the weather and said “What the heck happened!”.

Ken Kremer met up with a group of lucky Tweeters at the KSC press center a few minutes after Atlantis blast off.  Back dropped by the world famous countdown clock, pad 39 A.  Do you think they are having a blast?   Credit: Ken Kremer
Ken Kremer met up with a group of lucky Tweeters at the KSC press center a few minutes after Atlantis blast off. Back dropped by the world famous countdown clock, pad 39 A and US Flag, they appear to be celebrating their good fortune to be invited by NASA to witness the drama first hand and instantly transmit their experiences across all earth’s continents. Do you think they are having a blast? Credit: Ken Kremer

Perhaps an hour before launch the thick cloud layer at last dissipated and Atlantis punched through the deep blue skies, thrilling everyone at KSC including the over 100 tweeters allowed onto the press site for the very first time, some of whom I met and expressed utter joy at having the best seat in the house.

STS 129 is carrying 15 tons of critical spare parts to guard against the fast approaching day when the shuttle is retired from service in about 1 year. The shuttle is a true spaceship whose vital role and capability to transport large components and replacement equipment to the ISS will remain unmatched for decades to come.

“We appreciate all the effort making this launch attempt possible. We are excited to take this incredible vehicle for a ride to another incredible vehicle, the ISS,” Commander Charlie Hobaugh said shortly before launch.

During three spacewalks, astronauts will install two platforms to the station’s truss, or backbone which will be used to store the spare parts brought aloft and also known as Orbital Replacement Units, or ORU’s.

The six person crew of Space Shuttle Atlantis walk out from crew quarters at 10:38 AM to greet the cheering crowd of media and NASA officials and then head out to pad 39 A to strap in for space launch with hours.  Credit: Ken Kremer
The six person crew of Space Shuttle Atlantis walk out from crew quarters at 10:38 AM to greet the cheering crowd of media and NASA officials and then head out to pad 39 A to strap in for space launch with hours. Credit: Ken Kremer

Hobaugh is joined on Atlantis’ STS-129 mission by Pilot Barry E. Wilmore and Mission Specialists Leland Melvin, Randy Bresnik, Mike Foreman and Bobby Satcher. Atlantis will return with station resident Nicole Stott, marking the final time the shuttle is expected to rotate station crew members. Wilmore, Bresnik and Satcher are first-time space fliers. All future ISS residents will ride aboard Russian Soyuz rockets.
I visited the huge Tweet Up Tent which NASA set up for the first time at the Kennedy Space Center Press center so that ordinary folks from around the world could observe a shuttle launch and share it globally straight away as events unfolded.  This reminded me of a high tech command center.  Credit: Ken Kremer
I visited the huge Tweet Up Tent which NASA set up for the first time at the Kennedy Space Center Press center so that ordinary folks from around the world could observe a shuttle launch and share it globally straight away as events unfolded. This reminded me of a high tech command center. Credit: Ken Kremer

Indian TV interview with Ken Kremer at Launch Pad 39 A on NASA’s future, at this link

Read my earlier reports from KSC on the flight of Atlantis and Atlas launch attempt here:
Tweeters and Atlantis Ready for Launch
Clock Ticking for Shuttle Atlantis on Critical Resupply Mission
Atlas Launch halted by ORCA; Shuttle Atlantis Next in Line
Ken Kremer’s website

Video Preview of Next Shuttle Mission

The next space shuttle mission STS-129, slated to launch next Monday Nov. 16, is a “spare parts and stock-up” mission. And the needed extra parts and supplies delivered to the International Space Station by Atlantis will mean spare years on the station’s life once the space shuttle fleet is retired. The mission is a landmark of sorts — not sure if it is a good landmark or bad — but STS-129 is scheduled to be the last space shuttle crew rotation flight. From here on out, crew rotation will be done by the Soyuz and any future commercial vehicle that may come online. Besides the crew, a payload of spiders and butterfly larvae will be on board Atlantis for an experiment that will be monitored by thousands of K-12 students across US. Find out more about the flight with a video preview of the mission, below.

STS-129 will be commanded by Charlie Hobaugh and piloted by Barry Wilmore. Mission Specialists are Robert Satcher Jr., Mike Foreman, Randy Bresnik and Leland Melvin. Wilmore, Satcher and Bresnik will be making their first trips to space. The mission will return station crew member Nicole Stott to Earth.

The crew will deliver two control moment gyroscopes and other equipment, plus the EXPRESS Logistics Carrier 1 and 2 to the station. The mission will feature three spacewalks.

Masten wins $1 million X-Prize on Last Possible Day

The X-Prize competition for building a lander vehicle capable of making a simulated landing and liftoff on the Moon has come to a close, with the 1st place, $1 million award going to Masten Space Systems for their vehicle, Xoie (pronounced like the name ‘Zoey’). Armadillo Aerospace came in a close second, and received $500,000 for their Scorpius rocket. The Northrop Grumman Lunar Lander X-Prize challenge was initiated to spur development of lunar landing vehicle by a privately funded institution. The last of the challenge flights occured Friday, October 30th, and the competition came down to the wire, as Masten encountered problems on Wednesday and Thursday challenge windows that delayed their final flight to the last day of the challenge.

The challenge was divided into two categories, Level 1 and Level 2. Here’s the rules for the two categories, as taken from the X-Prize Foundation website:

Level 1, requires a rocket to take off from a designated launch area; climb to a low, fixed altitude; and fly for at least 90 seconds before landing precisely on a different landing pad. The flight must then be repeated in reverse. Both flights, along with all of the necessary preparation for each, must take place within a two and a half hour period. $500,000 in prizes was initially allocated to Level 1.

The more difficult course, Level 2, requires the rocket to fly for 180 seconds before landing precisely on a simulated lunar surface constructed with craters and boulders. The minimum flight times are calculated so that the Level 2 mission closely simulates the power needed to perform a real descent from lunar orbit down to the surface of the Moon. A $1 million First Place and a $500,000 second place prize remain to be claimed by the winners of Level 2

Xoie experienced communications and leakage issues on Wednesday and Thursday. A leak on Thursday afternoon caused a small fire, but the team spent the night fixing the problem, and the craft flew wonderfully on Friday., October 30th. Xoie is a lighter and more powerful version of Masten’s Level 1 vehicle, Xombie. (Wouldn’t it have been more fitting if Xombie flew the day before Halloween, though?)

Both teams met the qualifications for the Level 2 prize, but Masten had an average landing accuracy of 19 cm (7.5 in), while Armadillo Aerospace acheived an accuracy of 87 cm (34 in). This means that Masten beat out Armadillo on the very last day of the challenge by little over two feet! What an exiting space race!

Masten and Armadillo qualified for the Level 1 prizes earlier this year, with Armadillo claiming the first prize of $350,000 and Masten second place with $150,000. An awards ceremony will be held for the winning teams on November 5th.

Here’s a video of the winning flight:


Neither company plans to rest on their laurels after these victories, though. Masten said in a press release, “We are building up a good head of steam. Next year is going to be full of bigger, faster, and higher. Winning contests is fun, but we won’t rest until we’re flying a fleet of vehicles into space carrying all sorts of commercial payloads.” They have been awared a Department of Defense Small Business Innovation and Research contract to use their vehicles in network communications testing. Masten also has a program that will fly payloads into space for $250 a kilogram.

Armadillo Aerospace has flown a vehicle in every X-Prize cup so far, and company founder John Carmack said after their Level 2 challenge flight on September 14th, “Since the Lunar Lander Challenge is quite demanding in terms of performance, with a few tweaks our Scorpius vehicle actually has the capability to travel all the way to space. We’ll be moving quickly to do higher-altitude tests, and we can go up to about 6,000 feet here at our home base in Texas before we’ll have to head to New Mexico where we can really push the envelope. We already have scientific payloads from universities lined up to fly as well, so this will be an exciting next few months for commercial spaceflight.” See our coverage on Universe Today of Armadillo’s qualifying test flight for more information and cool videos.

This is far from the last challenge that the X-Prize foundation has come up with. The Google Lunar X-Prize will award $30 million to the first privately funded team to send a robot lander to the Moon, travel 500 meters, and transmit videos and data back to the Earth. There are X-prize competitions in areas other than exploration and astronomy, including the life sciences, energy and the environment, and education and global development.

Source: SatNews, X-Prize Foundation

Launches and Dockings and Robots, Oh My!

It was a busy weekend in the world of space flight — both present and future — and so we’ll try to fit it all in one article, and include a couple of videos to help tell the stories. Before that, however, just a reminder that the Ares-I-X is slated to roll out to launchpad 39-B early Tuesday morning at 12:01 am EDT, to begin preparations for the scheduled Oct. 27 first test launch. If you’re an early bird, (or a night owl) watch the six-hour trip on NASA TV.

And now on to this weekend’s launch story:

The 600th launch of an Atlas rocket took place on a foggy Sunday morning, Oct. 18, from Vandenberg Air Force Base in California. A new global weather observatory (DMSP F-18) for America’s military was lofted into polar orbit. Watch the video below, and click here to watch a video of the Centaur upper stage which created a sensation as it flew over Europe later in the day when it dumped a load of excess propellant.

On Saturday, Oct. 17, A Progress cargo spacecraft, delivering 2.5 tons of supplies, successfully docked to the space station at 9:40 pm EDT. Here’s the video replay of that event from NASA TV:

Also on Sunday, nineteen teams pushed their robot competitors to the limit, and three teams claimed a total of $750,000 in NASA prizes at this year’s Regolith Excavation Challenge on Oct. 18. This is the first time in the competition’s three-year history that any team qualified for a cash prize, the largest NASA has awarded to date.

After two days of intense competition hosted at NASA’s Ames Research Center at Moffett Field, Calif., organizers conferred first place prize of $500,000 to Paul’s Robotics of Worcester, Mass. Terra Engineering of Gardena, Calif., was a three-time returning competitor and was awarded second place prize of $150,000, and Team Braundo of Rancho Palos Verde, Calif., took the third place of $100,000 as a first-time competitor.

Competitors were required to use mobile, robotic digging machines capable of excavating at least 330 pounds of simulated moon dirt, known as regolith, and depositing it into a container in 30 minutes or less. The rules required the remotely controlled vehicles to contain their own power sources and weigh no more than 176 pounds.

Read more about the competition here, and see lots more images and videos of the event here.

Trips to Mars in 39 Days

Using traditional chemical rockets, a trip to Mars – at quickest — lasts 6 months. But a new rocket tested successfully last week could potentially cut down travel time to the Red Planet to just 39 days. The Ad Astra Rocket Company tested a plasma rocket called the VASIMR VX-200 engine, which ran at 201 kilowatts in a vacuum chamber, passing the 200-kilowatt mark for the first time. “It’s the most powerful plasma rocket in the world right now,” says Franklin Chang-Diaz, former NASA astronaut and CEO of Ad Astra. The company has also signed an agreement with NASA to test a 200-kilowatt VASIMR engine on the International Space Station in 2013.

The tests on the ISS would provide periodic boosts to the space station, which gradually drops in altitude due to atmospheric drag. ISS boosts are currently provided by spacecraft with conventional thrusters, which consume about 7.5 tons of propellant per year. By cutting this amount down to 0.3 tons, Chang-Diaz estimates that VASIMR could save NASA millions of dollars per year.

The test last week was the first time that a small-scale prototype of the company’s VASIMR (Variable Specific Impulse Magnetoplasma Rocket) rocket engine has been demonstrated at full power.

Plasma, or ion engines uses radio waves to heat gases such as hydrogen, argon, and neon, creating hot plasma. Magnetic fields force the charged plasma out the back of the engine, producing thrust in the opposite direction.

They provide much less thrust at a given moment than do chemical rockets, which means they can’t break free of the Earth’s gravity on their own. Plus, ion engines only work in a vacuum. But once in space, they can give a continuous push for years, like wind pushing a sailboat, accelerating gradually until the vehicle is moving faster than chemical rockets. They only produce a pound of thrust, but in space that’s enough to move 2 tons of cargo.

Due to the high velocity that is possible, less fuel is required than in conventional engines.

Currently, the Dawn spacecraft, on its way to the asteroids Ceres and Vesta, uses ion propulsion, which will enable it to orbit Vesta, then leave and head to Ceres. This isn’t possible with conventional rockets. Additionally, in space ion engines have a velocity ten times that of chemical rockets.

Specfic impulse and thrust graph. Credit: NASA
Specfic impulse and thrust graph. Credit: NASA

Rocket thrust is measured in Newtons (1 Newton is about 1/4 pound). Specific impulse is a way to describe the efficiency of rocket engines, and is measured in time (seconds). It represents the impulse (change in momentum) per unit of propellant. The higher the specific impulse, the less propellant is needed to gain a given amount of momentum.

Dawn’s engines have a specific impulse of 3100 seconds and a thrust of 90 mNewtons. A chemical rocket on a spacecraft might have a thrust of up to 500 Newtons, and a specific impulse of less than 1000 seconds.

The VASIMR has 4 Newtons of thrust (0.9 pounds) with a specific impulse of about 6,000 seconds.

The VASIMR has two additional important features that distinguish it from other plasma propulsion systems. It has the ability to vary the exhaust parameters (thrust and specific impulse) in order to optimally match mission requirements. This results in the lowest trip time with the highest payload for a given fuel load.

In addition, VASIMR has no physical electrodes in contact with the plasma, prolonging the engine’s lifetime and enabling a higher power density than in other designs.

To make a trip to Mars in 39 days, a 10- to 20-megawatt VASIMR engine ion engine would need to be coupled with nuclear power to dramatically shorten human transit times between planets. The shorter the trip, the less time astronauts would be exposed to space radiation, and a microgravity environment, both of which are significant hurdles for Mars missions.

VASIMR. Credit: Ad Astra
VASIMR. Credit: Ad Astra

The engine would work by firing continuously during the first half of the flight to accelerate, then turning to deaccelerate the spacecraft for the second half. In addition, VASIMR could permit an abort to Earth if problems developed during the early phases of the mission, a capability not available to conventional engines.

VASIMR could also be adapted to handle the high payloads of robotic missions, and propel cargo missions with a very large payload mass fraction. Trip times and payload mass are major limitations of conventional and nuclear thermal rockets because of their inherently low specific impulse.

Chang-Diaz has been working on the development of the VASIMR concept since 1979, before founding Ad Astra in 2005 to further develop the project.

Source: PhysOrg

South Korea Launches Rocket; Satellite Fails to Reach Its Orbit

South Korea successfully launched its first rocket on Tuesday, but the satellite payload failed to reach its designated orbit, officials said. The rocket, a two-stage rocket, called the Naro lifted off on schedule at 5:00 pm local time, (0800 GMT). The first stage separated successfully less than five minutes after lift-off and the South Korean-built 100-kilogram (220-pound) scientific research satellite was placed into Earth orbit. But science and technology minister Ahn Byong-Man said it was not following the designated orbit, hampering communications with mission control. “All aspects of the launch were normal, but the satellite exceeded its planned orbit and reached an altitude of 360 kilometres (225 miles),” Ahn said.
Continue reading “South Korea Launches Rocket; Satellite Fails to Reach Its Orbit”

NASA Tests Inflatable Heat Shield

NASA conducted a successful test Monday morning of a new type of heat shield that could make it possible to land larger payloads on Mars. The Inflatable Re-entry Vehicle Experiment (IRVE) demonstrated an inflatable heat shield which could slow and protect spacecraft entering atmospheres at hypersonic speeds. “This was a small-scale demonstrator,” said Mary Beth Wusk, IRVE project manager, based at Langley Research Center. “Now that we’ve proven the concept, we’d like to build more advanced aeroshells capable of handling higher heat rates.”

IRVE launch from Wallops Island, Virginia.  Credit: NASA
IRVE launch from Wallops Island, Virginia. Credit: NASA

IRVE was vacuum-packed into a 38 cm (15-inch) diameter payload shroud and launched with a Black Brant 9 sounding rocket from NASA’s Wallops Flight Facility on Wallops Island, Va., at 8:52 a.m. EDT. The 3 meter (10-foot) diameter heat shield, made of several layers of silicone-coated industrial fabric, inflated with nitrogen to a mushroom shape in space several minutes after liftoff.

At four minutes into the flight, the rocket reached 210 km (131 miles), and deployed the heat shield, which took less than 90 seconds to inflate. According to the cameras and sensors on board, which relayed real-time data back to engineers on the ground, the heat shield expanded to its full size and went into a high-speed free fall. The key focus of the research came about six and a half minutes into the flight, at an altitude of about 50 miles, when the aeroshell re-entered Earth’s atmosphere and experienced its peak heating and pressure measurements for a period of about 30 seconds.

“Our inflation system, which is essentially a glorified scuba tank, worked flawlessly and so did the flexible aeroshell,” said Neil Cheatwood, IRVE principal investigator and chief scientist for the Hypersonics Project at NASA’s Langley Research Center in Hampton, Va. “We’re really excited today because this is the first time anyone has successfully flown an inflatable reentry vehicle.”

NASA engineers check out the Inflatable Re-entry Vehicle Experiment (IRVE) in the lab. Credit: NASA/Sean Smith
NASA engineers check out the Inflatable Re-entry Vehicle Experiment (IRVE) in the lab. Credit: NASA/Sean Smith

Inflatable heat shields hold promise for future planetary missions, according to researchers. To land more mass on Mars at higher surface elevations, for instance, mission planners need to maximize the drag area of the entry system. The larger the diameter of the aeroshell, the bigger the payload can be.

For more information on the problems of landing on Mars, and other inflatable heat shields and supersonic decelerators that are being developed, check out our previous article with Rob Manning of JPL and Glen Brown of Vertigo, Inc.

Fact Sheet on IRVE (pdf)

Sources: NASA, NASA