Weather May Scrub Launch of NASA's DART Spacecraft
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DART pulls up to Multiple beam Beyond Line-of-sight Communications (MUBLCOM) satellite. Built to test automated rendezvous technology, DART expertise should also prove helpful in latching rocket motor to Hubble Space Telescope as part of de-orbiting plan for the huge observatory. CREDIT: OSC |
NASA researchers are one day away from testing what they hope will be the space agency's first unmanned vehicle capable of meeting up with other orbiting spacecraft. That is, as long as the weather holds.
Launch officials said Monday that there is a 90 percent chance weather violations could scrub the Oct. 26 launch of DART, a spacecraft designed to seek out and rendezvous with a satellite in Earth orbit. If successful, DART's flight could prove key technologies developed by NASA to build autonomous, rendezvous-ready spacecraft.
"We have launched on 90 percent chance of violation days before," NASA launch director Omar Baez said during a prelaunch press conference today at Vandenberg Air Force Base in California.
If weather does scrub the launch, a second attempt could occur as soon as Thursday, he added.
DART, short for Demonstration of Autonomous Rendezvous Technology, is expected to launch from the air atop a four-stage Orbital Sciences Pegasus XL rocket at 2:13:20 p.m. EDT (1813:20 GMT) in a flight staged from California's Vandenberg Air Force Base. A former passenger jet, Stargazer L-1011, will carry the rocket into launch position 40,000 feet (12,192 meters) above the Pacific Ocean.
"We're running on a lot of excitement...but we don't want to jeopardize all the money and effort into this mission," said Jim Snoddy, DART project manager from NASA's Marshall Space Flight Center, of the $95 million mission. "We want to make sure it goes safely."
NASA researchers believe the autonomous capabilities tested by DART will lay the foundation for future missions beyond Earth orbit, where an autopilot - instead of real-time remote control - may be more preferable during dockings. The mission is cooperative effort between NASA researchers and the Orbital Sciences Corporation (OSC), which developed the spacecraft.
"Whether you're going to the moon or Mars, you're always going to have to put things together in space," Snoddy said.
Spaceflight sans humans
While DART's launch marks the first flight of a U.S.-built unmanned rendezvous space vehicle, though the Russian Federal Space Agency's Progress and Soyuz vehicles have docked autonomously with space stations for years. Europe is also planning to launch the cargo ship Jules Verne, the first of its Automated Transfer Vehicles (ATV) to the International Space Station next year.
"DART carries it to the next step," Snoddy said, adding that once the spacecraft launches, it will be function independent of any human intervention. "We're automating everything from the ground operations to the flight operations, and we don't heavy antennas or flight boxes."
At the heart of the DART mission is a device called an advanced video guidance sensor (AVGS), which combines advanced optical and electronic ranging systems to approach its satellite target - the Multiple Paths Beyond Line-of-Site Communications (MUBLCOM) spacecraft launched in 1999.
A global positioning system (GPS) will also aid DART's rendezvous, and onboard software will test collision avoidance maneuvers, and direct the spacecraft to fly circles around MUBLCOM. An onboard camera will hopefully catch images of the rendezvous.
"We've done everything we can on the ground," Snoddy said. "The next step is to take it into space."
Air-to-space rocket
It should take DART and its Pegasus booster about 12 minutes to rocket into space once their Stargazer mothership drops them 100 miles (160 kilometers) out over the Pacific Ocean.
Once in orbit, DART is programmed to begin using its GPS system to establish its location then fire three hydrazine thrusters to chase its target satellite. The MUBLCOM spacecraft carries two sets of reflectors for DART to bounce ranging lasers off of, researchers said.
When DART flies within 621 miles (1,000 kilometers) of MUBLCOM, it is expected to switch over to its AVGS navigation system and hopefully fly rings around the spacecraft, with its closest approaching reaching about 16 feet (5 meters) before backing out and making another pass. About 24 hours after launch, DART's onboard batteries should begin to expire and the spacecraft will fire its engines self-destruct reentry path to burn up in Earth's atmosphere.
After DART's flight, researchers hope to study the data and apply it to future technology shakedown missions, including automated docking missions.
"This technology will become more important as we get farther away from Earth," Snoddy said.
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