The number of flowers, balloons, teddy bears and homemade signs continued to grow outside the Johnson Space Station in Houston, Texas, as hundreds arrived at a small, green patch to share their thoughts and prayers for the lost crew of the Columbia space shuttle.

"I can't stop crying," said Frances Grant, who travelled from southern California to pay her respects to 41-year-old Kalpana Chawla and her six colleagues.

"It is very painful for me to think about that beautiful, Indian woman who aspired to reach the heavens for all of us," Grant said.

One sign painted in blue, featuring a green earth and silver glitter paint for stars, read: 'Your bodies have returned to the earth, because they belong to the earth -- but your souls have gone to heaven, because they belong with Him.'

Other placards featured quotes from scriptures, personal notes, poems and pictures of the Columbia crew, still smiling in their pre-flight group photos.

"This is my first time here, but I just had to be here to share in the emotions that others have," said Stephan Deokiesingh of Houston, who stood quietly with his arms crossed and stared at a placard commemorating Chawla.

"It was good that an Indian woman made it this far," he continued. "It is just a tragedy that she did not come back."

The impromptu memorial surrounding the large double-sided concrete sign by the entrance to the space centre happened almost overnight, reminiscent of the tributes left at ‘Ground Zero' after the terrorist attacks of 2001.

It has become the focal point for ordinary people touched by the tragedy, an open-air ceremony going on throughout the day. Mourners and well-wishers milled about, placing their tributes, standing silently and shedding tears.

Some were there because of their personal relationships with the astronauts on board. Fanny Norgan touched a picture of Laurel Clark hung up on a fence. She then explained that she knew Clark because she worked at the school that her son attended.

"I asked her before she left who was going to take care of her son when she was gone," Norgan said. "He was missing his mother so much. Now I don't know what he will do."

Indian flags were placed side-by-side with American and Israeli flags, some splayed across the sign's concrete base, others fluttering in the warm wind.

"It's a testament to the diversity of this crew," remarked Houston local Ann Dahl. "It was also a testament to the fact that we need to unite."

The Indians in Houston, who came to the memorial site, were touched by what they witnessed.

"The whole world is in grief, not just Indians," said Arvine Patel. "Everyone here in the US is praying; we are all coming together.

"Chawla made her footsteps in space. Now she will be remembered forever."

Patel was among a group of people from a local BAPS temple who came to the site to pray for the astronauts.

Others kept a respectful distance as they made a semicircle, chanting the name of Swaminarayan and lightly tapping their hands.

They spoke highly of Chawla, mentioning that she spent money out of her own pocket to bring children from India to see the space centre.

"She was so bold to become an astronaut," said Janak Amin. "Even for this country, for a woman to do that, it is not easy."

Amidst the eulogies, though, some visitors were asking hard questions about what could have been done to save the astronauts.

"This is the second time that something this horrendous has happened with a shuttle," said Sabrina Johnson, who brought a poem and an angel to place among the wreaths and balloons.

"I know they check everything, but there comes a time when we need to take another look at the technology," she said. "These are lives at stake here."

Disagreeing was Carey Honganen, who became tearful the moment he was asked for his thoughts on the Columbia crew.

"We have some of the best engineers here in the world," he said. "There are hundreds of people working behind the scenes to ensure the astronauts are okay. You can't just shut down everything overnight.

"We just take the space programme for granted; we forget that it is a fragile system until something happens."

Grant hoped that the tragedy would not result in the closure of NASA's programmes, as some around the memorial discussed, or people giving up their dreams of going into space.

She explained that her bond with India was formed in the 1940's, when she lived in Bombay and performed as a singer at the Taj Mahal and India Radio as 'Molly O'Connor'.

That's why, she said, it was so important for her to touch the Tricolour to share her feelings with everyone in India.

"The beauty of it is, that up there, Chawla is helping us, because the love we all share here has brought us together across the oceans."

The Columbia Crash: The Complete Coverage