Posted on Oct 28, 2009 01:02:37 PM | Dan Kanigan
After shrugging off some delays due to clouds, Ares I-X has lifted off into the Florida sky and done what it was designed to do: lift off, test the flight software, perform a separation maneuver, and test the recovery system. This is a great day for the Ares I-X Mission Management Office, and a first step toward NASA’s next generation of human spaceflight. More details on the data will be coming out over the next several days, weeks, and months.
Triboelectrification Questions? Try This.
Posted on Oct 28, 2009 11:24:29 AM | Dan Kanigan
An earlier blog post attempted to answer questions about triboelectrification. Since there are still a few questions floating around we're reposting it for those who missed it on the first go-round.
Flight Rules and Triboelectrification (What
the Heck is That?)
The skies look clear except for some high clouds, there’s no rain in the
immediate forecast, so why might a rocket not launch? The answer is something
called triboelectrification. While this isn’t a word you encounter every day,
you might experience it if you walk across a dry carpet or brush up against a
cat and then touch a metal surface: it’s static.
In the case of Ares I-X, flying through high-level clouds can generate
“P-static” (P for precipitation), which can create a corona of static around
the rocket that interferes with radio signals sent by or to the rocket. This
would create problems when the rocket tries to transmit data down to the ground
or if the Range Safety Officer at Cape Canaveral Air Force Station needed to
send a signal to the flight termination system. Until the 45th Space Wing and
observer aircraft indicate that the skies are clear, Ares I-X will wait them
Why a Four-Hour Launch Window?
Posted on Oct 28, 2009 09:05:55 AM | Dan Kanigan
One question that
comes up a lot is why Ares I-X has a four-hour launch window. After all, unlike
the Space Shuttle, it doesn’t have to rendezvous with the Space Station, so
what’s the challenge? Actually, there are several.
First, the Eastern Range typically allots 4-hour launch windows. Given the
duration of Ares I-X (about seven minutes from liftoff until the final pieces
splash down), more time is not required. As was demonstrated on the first
launch attempt, the rocket can be reset quickly, so four hours was considered
plenty of time to wait out weather and technical challenges.
Next, there are human limitations. Console operators in the Launch Control
Center must be at their consoles at least 7 hours before the planned launch.
When you add the 4-hour window this means that operators may have to be on
station for 11 hours before launch. There is also a lot of work to do after
launch or after a scrub.
Additionally, anyone familiar with Florida weather understands that winds
typically pick up later in the day as the atmosphere heats up and interacts
with evaporation from the ocean. Central Florida’s “afternoon thunderstorms”
produce a terrific number of lightning strikes. High winds are a problem for
any launch. Because of its experimental nature, Ares I-X has very conservative
wind constraints—20 knots (nautical miles per hour—about 23 statute miles per
hour) as opposed to the Space Shuttle, which can fly in winds up to 30 knots
(34.5 miles per hour).
A 4-hour window, gives the team
the ability to complete all the preparation work, wait for the right
combination of winds, weather and clouds and then go. Following the LCC
guidelines gives Ares I-X the best chance to collect the important data that we
need for next exploration steps we take.
Whatever Happened to the Five-Hole Probe?
Posted on Oct 28, 2009 08:45:51 AM | Dan Kanigan
Remember that probe
on the top of the rocket? It’s still being watched carefully today, and not
just because of its hard-to-remove cover.
As we noted yesterday, the five-hole probe is a very important set of sensors
for collecting aerodynamic data during the flight. It remained covered while
Ares I-X was rolled out to the launch pad and just prior to launch because the
avionics team did not want water, bugs, bird messes, or other debris getting on
or in the sensors. Inside the five holes is a diaphragm of flexible material
against which air vibrates to produce data. If water or foreign object debris
(FOD) gets onto the diaphragm, there is a risk that the data from the sensors
could be harder to interpret after the flight. Once the Ground Operations team
removed the cover, there is no way to put it back on short of rolling the
rocket back into the Vehicle Assembly Building. The I-X team knew this might
happen, but now that the cover is off, what next? Just to add to the challenge,
Cape Canaveral expected (and got) an inch and a half of rain on Tuesday night.
What NASA did was take a spare five-hole probe out to the pad, put it on the
fixed service structre and gave it a similar exposure to rain as the flight
hardware. The spare unit was tested before and after the rain to determine its
effects on the sensors’ behavior. In this way, NASA will be able to account for
any changes in sensor measurements due to water on the sensor and use that
information to interpret the data after the flight. This is just one of many
lessons the Ares team is learning as it continues testing on the Ares I-X
Posted on Oct 27, 2009 11:30:34 AM | Dan Kanigan
Well, the weather didn’t cooperate with us today. Winds and
clouds we’re outside of our allowable limits, so we’re packing it in and we’ll
try again tomorrow. Launch window opens at 8:00 EDT on Oct. 28 and continues
through until noon.
Launch coverage on
NASA TV begins at 5 am EDT – www.nasa.gov/ntv
When is a Rocket Launch Like a Soap Opera?
Posted on Oct 27, 2009 10:27:51 AM | Dan Kanigan
Drama can take many forms. A good drama has suspense, sudden pitfalls, unexpected turns, and emotional intensity. You don’t need to go to the movies for that. Today, you can just turn on NASA TV and watch the challenges experienced by the Ares I-X flight test. Since the originally scheduled launch time of 8 a.m. Eastern Time, we’ve seen holds due to weather, trouble pulling off a cover for a sensor on top of the rocket, a ship sailing into the splashdown portion of the range, and then another last-minute weather delay due to clouds.
Like any good drama, we enjoy a great sigh of relief when all comes right in the end. Keep watching, the adventure continues.
The Pointy End of the Rocket
Posted on Oct 27, 2009 09:09:18 AM | Dan Kanigan
There’s a running joke around NASA that the most
important thing about rocket travel is that “the pointy end goes up.” That
seems simple enough—and that’s what we expect Ares I-X to do today. But have
you ever wondered what is ON the pointy end of the rocket? You might be surprised.
Rather than an actual point or smooth, aerodynamic surface, the very top of the
Ares I-X rocket is capped by an instrument called the “five-hole probe.” As its
name suggests, this instrument has five holes on its conical point, which take
in air during flight. The probe is actually a set of sensors that collects
aerodynamic data, including total air pressure, static air pressure, angle of
attack, and other measures that verify how well the vehicle is being
controlled—one of the primary objectives of the test.
Because of the importance of this sensor, the five-hole probe is kept
under a protective cover, which will be removed by someone standing on top of
the launch gantry and pulling it off with a lanyard. The cover will be removed
about 45 to 50 minutes before launch time. Once the cover is off, the five-hole
probe will be ready to slice through the air and make its contribution to the
flight test…pointy end up, of course.