Discovery, the first space shuttle to be launched since the Columbia crash two years ago, will carry a photograph of India-born astronaut Kalpana Chawla and mementos of her colleagues who perished in the tragedy.
Jean P Harrison, widower of Chawla, said he was sending a photograph of his wife aboard Discovery, which is poised for liftoff day with a five-man, two-woman crew on Wednesday.
The picture of Kalpana is from her college days in India, where she is sitting in her dorm room surrounded by photographs of aircraft and one of a space shuttle.
The countdown for the Discovery launch began at 3.30 am on Monday and will continue till the Wednesday launch.
Relatives of at least three of the seven Columbia astronauts, Jonathan Clark, widower of astronaut Laurel; Sandy
Anderson, widow of astronaut Michael Anderson; and Doug Brown, brother of astronaut David Brown plan to attend the launch of Discovery.
They are also sending mementoes up with Discovery's crew, such as flags, gold medallions and a Columbia mission pin.
The Columbia families said they hoped Discovery's mission will be flawless, enabling the National Aeronautics and Space Administration in its pursuit of new missions to the moon and Mars.
"But then, there is also the pain of knowing that our loved ones didn't come back. So that leaves an emptiness that is somewhat reminded by the fact that there's another launch," said Jonathan Clark, the NASA flight surgeon whose astronaut-wife, Laurel, died aboard Columbia.
Columbia crashed in February 2003 when a chunk of foam that separated from its external tank during launch caused it
to disintegrate upon re-entry into atmosphere.